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Car Forum / Mitsubishi Cars / May 200890 Eclipse GSR4 repaired ECU diagnosis
Hi ppl. I have a 90 Eclipse GSR4 and it's my first car. (pls don't laugh) Probably all of you already know all the details of this model: turbo,AWD,DOCH 16 valve 2.0 L,manual gear,left steering (in UAE where I'm located, many cars are coming from Japan) Unfortunately I've ignored some symptoms, not knowing how serious it was, and the ECU burned while driving, luckily in second gear at ~30 km/h. I've crane it to a garage, took off the ECU, replaced the capacitors on the PCB and repair the hole in the PCB :) since I could not find a second-hand replacement anywhere. A brand new one from the Mitsubishi dealer is too expensive for me, and considering the price I paid for the entire car, is out of the question. After repairing the ECU, it seems I got sparks and fuel pressure, because I can hear & feel a repeately short combustion as long as I keep trying to crank it. My mechanic friends are saying the injectors are not pulsed by the ECU. (I'm a software developer, so I believe them) I've unplugged all 4 wires going in the injectors and measured the voltage and conectivity. Each injector receives 14-15 V on both wires when turnining the ignition ON, and a variating 10-12 V while cranking. We did lots of other sorts of tests, but could not find nothing wrong. I've checked again and again the ECU, but since I don't have any manual or testing values to make on the board, I cannot be sure if something else got damaged. I'm also thinking that a sensor could've been damaged when the ECU burned, and that's a good reason for me not spending money on another ECU, until I'm sure mine is not functioning correctly. I will appreciate any hint of what to do next and how to make a correct diagnosis. Thanks > Hi ppl. > I have a 90 Eclipse GSR4 and it's my first car. (pls don't laugh) > Probably all of you already know all the details of this model: > turbo,AWD,DOCH 16 valve 2.0 L,manual gear,left steering (in UAE where I'm located, many cars are coming from Japan) > Unfortunately I've ignored some symptoms, not knowing how serious it was, and the ECU burned while driving, luckily in second gear at ~30 km/h. > I've crane it to a garage, took off the ECU, replaced the capacitors on the PCB and repair the hole in the PCB :) since I could not find a second-hand replacement anywhere. Hard to say , if there haven't been other components as well which may be blown as a cause or a result of the burning. > A brand new one from the Mitsubishi dealer is too expensive for me, and considering the price I paid for the entire car, is out of the question. > After repairing the ECU, it seems I got sparks and fuel pressure, because I can hear & feel a repeately short combustion as long as I keep trying to crank it. > My mechanic friends are saying the injectors are not pulsed by the ECU. (I'm a software developer, so I believe them) > I've unplugged all 4 wires going in the injectors and measured the voltage and conectivity. > Each injector receives 14-15 V on both wires when turnining the ignition ON, and a variating 10-12 V while cranking. As I understand this are open circuit measurements. It may well be, that the driving circuit can not pump the necessary current, if it sees the low impedance of the injector coils. An overheated power stage may have been the primary cause for the ECU to get in fire. > We did lots of other sorts of tests, but could not find nothing wrong. > I've checked again and again the ECU, but since I don't have any manual or testing values to make on the board, I cannot be sure if something else got damaged. The best way to get more informations would be to connect a scope in parallel to the injectors, to see the impulse shape and duration at the coils. You further should check the fuel pressure, which should be about 1,8 - 2 bar with the throttle in starting position ( almost closed). Remove the plugs after you have cranked the engine for a reasonable time. They should be wet after all. If not the injectors haven't properly opened. > I'm also thinking that a sensor could've been damaged when the ECU burned, and that's a good reason for me not spending money on another ECU, until I'm sure mine is not functioning correctly. > I will appreciate any hint of what to do next and how to make a correct diagnosis. If the above mentioned tests seem to deliver appropriate results, it still may be that the injector pulses are out of phase with the ignition sparks. This can be due to a problem with the crank- or camshaft sensor or the corresponding circuit on your PCB. Marcel Baum Marcel, please excuse my rush when I've posted. I'm so happy to find ppl trying to help me. I'll tell you the whole story as much as I know it. I don't have the technical history of the car, so many infos may not be actual facts but observations of an unexperienced driver (me). All seems to be original on the car (no modifications), which was maintained quite good by the previous owner. Since I bought the car (8 months back) I've changed the front axel boots, the oil in the gear boxes, topped the coolant, changed the oil every 3000 km, filled with gas and washed it :) I was very happy driver, but I was wrong. Ever since I bought it, the car randomly and rarely failed to start from the first try, when the humidity was very high or the car stayed for a couple of days in the parking. I thought was normal for an old car, or at least ok. Wrong! Moreover, I've ignored other symptoms like engine stalling after it started, and once, even after about 1 min. after I've started driving. That was the time to take out the ECU and check the electrolytic capacitors for leaks, and replace them after cleaning the board. But I didn't, misinterpreting the symptoms as many others, as I read later on the internet. One day it happened: the leaks made enough corrosion on the circuit board creating the short that "killed" my car, as I described in my first post. Was no use to check the fuses or try starting the engine. I've even seen a small thread of white smoke coming from the dash-board. From the sound and the smell, I knew that was an electrical short. The car was craned to my friend's garage, and the ECU was removed and opened. I've started looking for a replacement and at the same time research on internet for possible causes, etc. I was also afraid to try a new one which could've been damaged if the cause was not "inside that box" :) But, as much as I've tried, I couldn't get one that at least matches the number of pins, not saying about the product code. Next try was to order a used one on the net, but all answers were "Sorry, we don't have it in stock". Only Foreign Auto from Tampa replied possitive on rebuilding mine but when I put some delivery & warranty questions they replied too briefly: "CALL ...", so I lost my trust. In the meantime, I've decided to try myself rebuilding it. My appologies for making you read so much, but I'm almost done now :) Went to the garage and test it: - spark is coming on all 4 plugs (don't know if timing is correct, yet) - fuel comes on the pipe when cranking, so I assume the fuel pump works (also got repeatedly combustion for a fraction of a second) - didn't measured the fuel pressure with a gauge as supposed to, but the mechanics said "looks ok" - suplying the engine with fuel directly, the engine runs (with incorrect combustion, of course); we did a short test only - suplying the injectors with fuel from a can, engine doesn't start; our guess will be all injectors are staying closed - plugs were removed, cleaned, but no sign of being wet, so again we guess no fuel cames from any injector. - checked the wiring for connectivity, resistance & supplied voltage, but I had no data to compare with (only today I found some in the manual I bought from www.alldatadiy.com) - a couple of relays I found were checked and passed, but I'll post again after checking all mentioned on the electrical diagram (I would bet on the noise filter) I am really appreciating your help and patience. I hope is all more clear now and is making sense. Many thanks, Bogdan Bogdan, It seems as if the engine was running on the weak side from the very beginning . You may either find a low fuel pressure (its essential that it reaches the pressure I have mentioned in my last reply) or you may have troubles with the starting solenoid valve . I would not rely in just seeing that fuel is pumped, the fuel pressure regulator may have a broken membrane and you will still have flow under open conditions but no sufficient pressure to overcome the injector nozzles. The following links are dealing with different BOSCH EFI systems , but even so Mitsu doesn't use Bosch, it seems to be a license production of a Japanese brand. So you definitely will find similarities between both systems http://www.ludd.luth.se/~rotax/motronic/motronic.html http://www.vectorbd.com/peugeot/bosch.html In http://users.exis.net/~audserv/bench.html you will find a bench test setup for the EFI , however I am not sure the pin layout is the same you have. As long as you haven't checked whether the power stage of your ECU is really capable to open the injectors and your fuel pressure is OK its really hard to come to a better conclusion. > Marcel, please excuse my rush when I've posted. > I'm so happy to find ppl trying to help me. > I'll tell you the whole story as much as I know it. > I don't have the technical history of the car, so many infos may not be actual facts but observations of an unexperienced driver (me). > All seems to be original on the car (no modifications), which was maintained quite good by the previous owner. > Since I bought the car (8 months back) I've changed the front axel boots, the oil in the gear boxes, topped the coolant, changed the oil every 3000 km, filled with gas and washed it :) > I was very happy driver, but I was wrong. > Ever since I bought it, the car randomly and rarely failed to start from the first try, when the humidity was very high or the car stayed for a couple of days in the parking. > I thought was normal for an old car, or at least ok. > Wrong! Moreover, I've ignored other symptoms like engine stalling after it started, and once, even after about 1 min. after I've started driving. [quoted text clipped - 10 lines] > Next try was to order a used one on the net, but all answers were "Sorry, we don't have it in stock". > Only Foreign Auto from Tampa replied possitive on rebuilding mine but when I put some delivery & warranty questions they replied too briefly: "CALL ...", so I lost my trust. > In the meantime, I've decided to try myself rebuilding it. > My appologies for making you read so much, but I'm almost done now :) [quoted text clipped - 6 lines] > - plugs were removed, cleaned, but no sign of being wet, so again we guess no fuel cames from any injector. > - checked the wiring for connectivity, resistance & supplied voltage, but I had no data to compare with (only today I found some in the manual I bought from www.alldatadiy.com) > - a couple of relays I found were checked and passed, but I'll post again after checking all mentioned on the electrical diagram (I would bet on the noise filter) > I am really appreciating your help and patience. > I hope is all more clear now and is making sense. > Many thanks, > Bogdan > - suplying the engine with fuel directly, the engine runs (with incorrect combustion, of course); we did a short test only IMHO this should have fried your catalytic converter, right? Norman Hi, What is trouble code? Can't you pull the code? Tony > Hi ppl. > I have a 90 Eclipse GSR4 and it's my first car. (pls don't laugh) [quoted text clipped - 12 lines] > I will appreciate any hint of what to do next and how to make a correct diagnosis. > Thanks Hi Tony! I've just found the manual of my car on www.alldatadiy.com and bought it. Since not all DSMs are having the same trouble codes and same configuration of the diagnosis port, and because my car doesn't start makes it complicated to get it to a garage which has a proper scan tool, I don't have yet an error code. Moreover, since the ECM (ECU) was damaged, I would not trust too much a trouble code of a possible faulty board. I am still planning to connect a multi-use tester to the diagnosis port, now that I have the correct way of doing it. As I read in the manual, there are lots of condition to be met previously the code extraction, in order for it to be correct. The wiring seems very complicated and must be checked before installing a new unit, to ensure that will not get damaged. Thanks for posting, and if you have some experience with code interpretation, please share it, because I'm sure I will get stuck again after reading one from a repaired unit. Please remember that I'm not even an electrician and I didn't have a scheme when trying to repair the damage. What I can tell you is that I found a site where the repair routine was nicely described & luckily the pictures were of the same circuit board. So, at least I know that what I did was not wrong, but not necessarily sufficient. I promise to post again as soon as I will have more details. Hi I have more news about my car, still not fixed though. I couldn't pull any diagnostic code... the ECM is still faulty. I've measured the injectors's resistance and were not damaged (lucky me). I've read on www.alldatadiy.com how to check the harness wiring to be sure I'll not damage another unit if installed. Since I could not find another ECU, and in this country nobody wants to be responsable of rebuilding it, I had to try to repair it again. Each injector is directly connected to ECU through 2 wires. /-------\ | 1 | 2 | \-------/ No 1 goes to the same pin, probably being the ground. Having 5 pins to pulse the injectors, the ECU uses 5 transistors sticked on it's radiator for this purpose. Took them all out from the board and the one connected to the "ground" stays opened at all times. Must be destroyed. I hope it's my last problem. Was located near the capacitor blown-up. It seems that the short made possible a high intensity current to flow through it's base and damage it. Unfortunatelly, was not on stock on the shops I've been. I'm sharing my experience with you because it may help somebody else facing someday the same problems. Please DO NOT IGNORE any symptoms that your car may show. I've learned this lesson in the hard way. If anyone knows a good forum about electronics, please share. Thanks for reading, Bogdan > I couldn't pull any diagnostic code... the ECM is still faulty. In my understanding, you can *always* pull an error code from the ECU - if it's a constant signal, the ECU reports an ECU error, which it even does when it's not running at all. You should check that first - if you don't get a signal on the ECU status port at all or a constant signal you shouldn't worry about anything than the ECU in the first place. Norman The injectors are tied to the ECU individually and are commoned to the MPI (+ 12 volt) relay. The ECU provides a ground when it wants the injector to inject fuel, it definitely is pulsed. Timing is very important, have you checked the dist output signals. Quiet right, if you don't get the right signal from the ECU, look there first. Constant high signal on the error output lead is a failed ECU, no output on the same lead is also a failed ECU. Normal is a steady pulse output. Failed to me means it's not working, could be because of a blown fuse, etc., external to the ECU. > > I couldn't pull any diagnostic code... the ECM is still faulty. > [quoted text clipped - 5 lines] > > Norman Hi Nirodac. Every thing you said is correct. My ECU is giving constant signal because is not working properly. Do you think those 4 transistors (reffer to my reply to Norman) are supposed to be signaled when each injector should be grounded? My tests are saying these transistors are functioning and that would mean the microprocessor is not signaling them. Do you think is possible for the processor to not signal because the fifth transistor which I found faulty is not giving enough power supply? I've noticed that a small filter is installed in parallel with this transistor. It's unbelievable but in this whole country there's nobody able to fix this. Most of the ppl have no idea about what I'm talking. I really miss my country... :( Hi Bornish Just a curious question, what country are you in? The following information applies specifically to ECU part number MD159561, from a 1991 Plymouth Laser (Eclipse), non turbo. I'm giving you this information because I believe it to be close to your ECU, if nothing else, it'll give you some insight into how the Mitsu ECU's are built. Looking at my ECU from my 1991 Eclipse (Ply Laser) the green power transistor near the center of the circuit board is a 2SB1335A, PNP, Vceo=80V, Vcb=5V, Ic=10 Amp, and power rating is 50 Watt. It subs to an NTE 378. This is nothing fancy, it's rated an audio power amp transistor. The other four transistors are part number (all 4) 2SD1415, NPN Darlington, 100V, 7A, 30 watt. These transistors provide the ground to the injectors, when the ECU wants gas injected into the cylinder. By the way just incase you have different transistors, remember the Japanese drop the first two characters on the device number. Example 2SB1335A will be printed as B1335A on the transistor. Check out the circuit trace at both ends of capacitor C4. C4 is located at the anode (non banded) end of the big diode in the center of the PCB. One side is the ground feed the other side is the 5 volt feed. There should NOT be a break in the trace on the +5 volt side. C4 is a tiny surface mount cap. Check very closely with a magnifying glass. Scrap off any protective coating if necessary. If you can power up the ECU with the cover off, you should be able to measure +5 volts at the center pin of the green (2SB1335A) power transistor, the negative of the meter is grounded on the anode side of the big diode in the middle of the PCB. This is the five volt regulator output. BEWARE, if you slip off this pin with your probe and short an adjacent pin,you will most likely toast the ECU. Remember that there may be a conformal coating on the PCB. You should be able to follow this trace right to the other end of the PCB and around to pin 42 of IC2, the second biggest chip on the circuit board. I think also that pin 43 of IC 4 (the big one) is also at 5 volts from this rail. There should be 5 volts at all points on this trace If your processor is not getting the 5 volts it needs to run, it will not be able to pulse the injectors, or do anything else for that matter. You should replace ALL your filter capacitors just on spec. This is a real issue with Mitsu ECUs. Remember also that this information refers to a specific ECU, while it may also apply to your ECU, it also may not. Good luck, and keep us posted. > Hi Nirodac. > Every thing you said is correct. My ECU is giving constant signal because is not working properly. [quoted text clipped - 4 lines] > It's unbelievable but in this whole country there's nobody able to fix this. Most of the ppl have no idea about what I'm talking. > I really miss my country... :( > Hi Bornish > Check out the circuit trace at both ends of capacitor C4. (...) One [quoted text clipped - 4 lines] > transistor, the negative of the meter is grounded on the anode side of the > big diode in the middle of the PCB. This is the five volt regulator output. Hi Nirodac, thanks for that posting! That helped me a lot with my problem (see "1992 Galant ECU Problem or not?"). Do you know the exact value of C4? During desoldering my cap was damaged (or by the electrolyte spilled over it), so I can't get its exact value (a LCR meter will read 15-50 nF), but I need to replace it. I you don't now its exact value, I'm still now sure what the function of C4 is - maybe you can tell me and I get a better hint of what capacity to guess at. Thanks, Norman C4 appears to be a bypass capacitor. It's positioned between the +5 volt rail and ground. Not critical in value, my guess is most likely .01 uF, but it could also be .1 uF, at about 20 volts. It's not marked on mine. For testing purposes you could run without it. Just why did you unsolder it. If the trace was broken you could have just placed a jumper wire across the break. Nirodac > > Hi Bornish > > Check out the circuit trace at both ends of capacitor C4. (...) One [quoted text clipped - 19 lines] > Thanks, > Norman > C4 appears to be a bypass capacitor. It's positioned between the +5 volt > rail and ground. It's parallel to C104 (a 100uF electrolyte cap) on mine - that's why I was wondering what C4 is for. C104 is there to stabilize the power suppy (the +5V rail), that's how far my somewhat limited knowledge of electronics brought me. I still can't figure out what C4 is supposed to do - filter freuquencies or what? > Not critical in value, my guess is most likely .01 uF, but > it could also be .1 uF, at about 20 volts. It's not marked on mine. Sigh. It's not marked on mine either. Just who had the smart idea of not marking ceramic SMD capacitors? So I'll have to take a wild guess at the capacity and hope operation will be stable. (I'm probably going for 0.1 or 0.033 nF because my local electronics dealer only stocks those two in that capacity range and I'm not up to ordering anything else. And bigger is better, anyway.) > For > testing purposes you could run without it. > Just why did you unsolder it. > If the trace was broken you could have just > placed a jumper wire across the break. The trace wasn't broken. I had 5 V on one side (towards the transisitor), but about 3,5 V (dropping to under 3V during load) on the other side (towards the ICs). It was either a bad connection with a resitance or a "short" (with some resistance) to ground. Because C4 had been covered with electrolyte, it was somewhat corroded and had electrolyte _under_ it - probably "shorting" C4. Since I've desoldered more than SMD component in my life I figured it to be safe - just take C4, clean everything, measure C4 with a LCR meter, buy a replace, solder it, happy car again. I think the bondings of the SMD cap have been somewhat corroded by the electrolyte, that's why I didn't come off undamaged. By the way, thanks *a lot* for your help! Norman > > C4 appears to be a bypass capacitor. It's positioned between the +5 volt > > rail and ground. [quoted text clipped - 5 lines] > can't figure out what C4 is supposed to do - filter freuquencies or > what? Electrolytes do hardly filter RF interferences. The little one in parallel will do this job. > > Not critical in value, my guess is most likely .01 uF, but > > it could also be .1 uF, at about 20 volts. It's not marked on mine. [quoted text clipped - 5 lines] > electronics dealer only stocks those two in that capacity range and I'm > not up to ordering anything else. And bigger is better, anyway.) Presumably its just a typing error but 0,1 or 0,033 n!F will be much to small. What you may need is 33 - 100nF ( or 0,033 - 0,1uF). > > For > > testing purposes you could run without it. [quoted text clipped - 17 lines] > By the way, thanks *a lot* for your help! > Norman Sooo, does the restoration of the 5 volts to the component side of C4 fix your problem? Did you have to replace the power transistor as you had suspected? Nirodac > > C4 appears to be a bypass capacitor. It's positioned between the +5 volt > > rail and ground. [quoted text clipped - 37 lines] > By the way, thanks *a lot* for your help! > Norman > "Norman Weiss" <fdo003@bigfoot.de> wrote in message > > The trace wasn't broken. I had 5 V on one side (towards the [quoted text clipped - 6 lines] > > Nirodac Hi, first of all, thanks again for you help, Nirodac. I replaced C4 (with a 0.1 uF cap), cleaned the PCB underneath it and resoldered the contact points - that indeed restored the 5V to the rest of the PCB (and most of all the ICs). That did the job and the car is running again. I test drove it without any problems. After that I took the car for a longer drive at night (assuming it's fixed). At first I thought my eyes had gone bad ("Yeah, it *was* a long day, after all..."), because the headlights seemed a little dim. And the dashboard illumination did too. And even the clock looked less bright than normal... When the radio started turning itself off and refused to turn back on, I finally got the clue - the +12V now... Turns out I had been driving on battery all the way (with the lights on). Luckily, the engine seems to be the thing in the car that runs the longest with low voltage - stranding on an Interstate with no lights is not my favourite on a very rainy, dark Friday night. As you have guessed, the battery didn't get charged, because the alternator voltage regulator circuit is broke. As Mitsubishi did a *superb* design on that car, the battery warning light is triggered by the alternator voltage regulation coil transistor - transistor broke, alternator voltage regulation coil dead, alternator dead, no battery charging, lots of load, battery about to die - and no warning light on! *sigh* As it looks, the regulator unit is not available by itself, so I've been looking around for a used or rebuilt alternator - will keep you updated. Norman Your welcome, glad I could help. The service manual shows the voltage regulator as a separate item (inside the alternator) as part of the brush holder assembly. It also shows the diodes as a separate assembly. Some manufacturers actually sell rebuild kits that include these parts, and brushes and bearings as well. But certainly the easiest repair is the replacement of the entire unit. Good Luck. Nirodac. > > "Norman Weiss" <fdo003@bigfoot.de> wrote in message > > > The trace wasn't broken. I had 5 V on one side (towards the [quoted text clipped - 36 lines] > > Norman > The service manual shows the voltage regulator as a separate item (inside > the alternator) as part of the brush holder assembly. It also shows the > diodes as a separate assembly. Yes, the IC regulator is a seperate part inside the alternator, although I expect it to be fully sealed, so it has to be replaced entirely. I suspect the main transistor to be broke, since that produces the error(s) I have now. I expect the diodes to be ok. I didn't know that they are seperated from the rest of the regulator, then again, that will probably not help me anyway. > Some manufacturers actually sell rebuild > kits that include these parts, and brushes and bearings as well. But > certainly the easiest repair is the replacement of the entire unit. Good > Luck. I'd love to find a rebuild kit that's resonably priced. My current options are (US$ = 1,25 * Euro): Junk yard alternator (working): 50 Euro Junk yard alternator (working, 3 months warranty): 80 Euro Rebuilt alternator from a part seller: 150 Euro Now for the Mitsubishi prices: IC regulator only: 250 Euro Alternator, rebuilt: 270 Euro (! Just 20 Euro more than the IC regulator) Alternator, new: 400 Euro. IMHO, the IC regulator is way overpriced. I'll probably go for a junk yard option. Maybe I'll take the regulator out of the junk yard alternator and put it into mine. Norman Ouch, that's pricey!! Nirodac > > The service manual shows the voltage regulator as a separate item (inside > > the alternator) as part of the brush holder assembly. It also shows the [quoted text clipped - 30 lines] > > Norman Just finished putting the new clutch in my sons car, took it for a test drive, and the battery wouldn't charge. Dismantled the alternator, inner slip ring is all chewed up, the alternator ran out of contact brush material. This sucks, replacement cost (Canadian dollars) $276.00, plus taxes. There was no indication, other than a dead battery. Nirodac > > The service manual shows the voltage regulator as a separate item (inside > > the alternator) as part of the brush holder assembly. It also shows the [quoted text clipped - 30 lines] > > Norman > Dismantled the alternator, inner > slip ring is all chewed up, the alternator ran out of contact brush > material. > This sucks, replacement cost (Canadian dollars) $276.00, plus taxes. There > was no indication, other than a dead battery. I feel your pain... My "new" alternator arrived today - it's a junk yard alternator for 80 Euro. Besides that it seems to me that the alternator warning light has been extremly bad designed by Mitsubushi - quite often it fails to go on by design. Norman Nirodac, I can't begin to tell you how helpful the post below was. My 1992 Expo LRV had symptoms similar to Bornish's. It cut out twice, then re-started each time after a few minutes. Then when we stopped for lunch, it wouldn't restart at all. We towed it home. No spark. Could be no signals (TDC and or crank angle) from distributor, or could be in the MPI computer. Tried to read codes with my multimeter. No codes at all, not even the steady pulsing that indicates no codes. Checked out the control relay, and determined that the computer had power and ground. Opened the computer up. Some crud around the 50 V, 47uF cap that's right behind the linear regulator 2SB1355 transistor. Powered it on the bench. 0 volts at all three leads of the 2SB1355. Removed the 2SB1355 and checked it out. It's good--at least it acts like a diode from base to emitter and anothe from base to collector. I'm hoping that one of the electrolytic caps has shorted and has crowbarred the supply, but I'm not optimistic. Nirodac, have you analyzed this regulator circuit to any great degree? Regards, Larry ++++++++Original post follows+++++++++ Hi Bornish Just a curious question, what country are you in? The following information applies specifically to ECU part number MD159561, from a 1991 Plymouth Laser (Eclipse), non turbo. I'm giving you this information because I believe it to be close to your ECU, if nothing else, it'll give you some insight into how the Mitsu ECU's are built. Looking at my ECU from my 1991 Eclipse (Ply Laser) the green power transistor near the center of the circuit board is a 2SB1335A, PNP, Vceo=80V, Vcb=5V, Ic=10 Amp, and power rating is 50 Watt. It subs to an NTE 378. This is nothing fancy, it's rated an audio power amp transistor. The other four transistors are part number (all 4) 2SD1415, NPN Darlington, 100V, 7A, 30 watt. These transistors provide the ground to the injectors, when the ECU wants gas injected into the cylinder. By the way just incase you have different transistors, remember the Japanese drop the first two characters on the device number. Example 2SB1335A will be printed as B1335A on the transistor. Check out the circuit trace at both ends of capacitor C4. C4 is located at the anode (non banded) end of the big diode in the center of the PCB. One side is the ground feed the other side is the 5 volt feed. There should NOT be a break in the trace on the +5 volt side. C4 is a tiny surface mount cap. Check very closely with a magnifying glass. Scrap off any protective coating if necessary. If you can power up the ECU with the cover off, you should be able to measure +5 volts at the center pin of the green (2SB1335A) power transistor, the negative of the meter is grounded on the anode side of the big diode in the middle of the PCB. This is the five volt regulator output. BEWARE, if you slip off this pin with your probe and short an adjacent pin,you will most likely toast the ECU. Remember that there may be a conformal coating on the PCB. You should be able to follow this trace right to the other end of the PCB and around to pin 42 of IC2, the second biggest chip on the circuit board. I think also that pin 43 of IC 4 (the big one) is also at 5 volts from this rail. There should be 5 volts at all points on this trace If your processor is not getting the 5 volts it needs to run, it will not be able to pulse the injectors, or do anything else for that matter. You should replace ALL your filter capacitors just on spec. This is a real issue with Mitsu ECUs. Remember also that this information refers to a specific ECU, while it may also apply to your ECU, it also may not. Good luck, and keep us posted. Nope, didn't spend any more time on this ECU than I needed. 12V is provided to this ECU on a number of different pins, have you powered all of them. Another poster had the same problem and thought it was the transistor, but I believe in the end it was an open trace. I found open traces on two of the three ECU's I've repaired for my son. Did you follow the instructions I posted. Check specifically for the break in the fat PC trace near the center of the PCB. That one broken trace caused the greatest problem. Mitsu (and other electronic manufacturers) place what looks like contact cement on some components to hold them to the PCB. My broken trace was under one of these patches of "glue". Make sure that a voltage measured on one side of this glue is also on the other side, most notably near the cap at the center of the ECU PCB. Try measuring the resistance with an ohm meter. I only reversed engineered the DC input far enough to fix my problem. Good luck > Nirodac, > [quoted text clipped - 89 lines] > > Good luck, and keep us posted. Comments interleaved. Larry > Nope, didn't spend any more time on this ECU than I > needed. 12V is provided > to this ECU on a number of different pins, have you > powered all of them? Just the main pair so far. You can see that they go to the fat trace that goes up the middle to the 2SB1355 used as a linear series regulator. > Another poster had the same problem and thought it was > the transistor, but I > believe in the end it was an open trace. I found open > traces on two of the > three ECU's I've repaired for my son. Wow! First for so many circuit card failures, and second for so many computer failures. I've had this 1992 since about 1994, and have 160K miles on it, and this is the first problem I've had. > Did you follow the instructions I posted? Check > specifically for the break > in the fat PC trace near the center of the PCB. Seems to be just fine, unfortunately. I can go from the pin to the 2SB1355 and way beyond it. I think I've checked +12V and ground, and +5 going out, but will re-check. > That one broken trace caused the greatest problem. > Mitsu (and other electronic manufacturers) place what > looks like contact > cement on some components to hold them to the PCB. This is standard practice for surface mount technology (SMT). You have to hold all the tinned, fluxed components in place after they are placed, until the populated board goes on the conveyor belt through the reflow oven (which, of course, reflows the solder). > My > broken trace was [quoted text clipped - 4 lines] > at the center of the ECU PCB. Try measuring the > resistance with an ohm meter. I've been using an ohmmeter. I'll try again and also trace the voltages with power on. It would be great to merely span some break with a few jumpers. Do you remember back in the mid 1960s when PC boards just went into wide use, and hairline fractures were common? They didn't use conformal coating then (as auto manufactures do now) and the radio service techs simply laid a coating of solder along every trace on the card. > I only reversed engineered the DC input far enough to fix > my problem. Well, right now my problem seems to be close to the power terminals, too. > Good luck Thanks, I'm counting on it. Larry Well, I was baffled by this for quite a while. The ohmmeter (one of those business-card-sized digital units) indicated continuity (beeps) on all the major traces, but I wasn't getting any voltages much beyond the where the connectors enter the card, when I powered it on the bench. It finally dawned on me that the ohmmeter will beep with some resistance, perhaps up to 10 ohms. The resistance of the entire card (through all the ICs and discrete circuits, etc.) is lower than that, so I wasn't measuring along the +5V trace--I was measuring between 5V and ground. It appears that the failure mode you observed is in play here, too. The trace seems to have failed under the big electrolytic cap nearest the connector, where all the brown crud was. I will put on new electrolytics. I'm ordering high-temperature (industrial/military grade) caps with -40C to +105C temp range, just as were on it. It doesn't make sense to use consumer grade caps in this harsh environment. And they only cost a few pennies more. I'm reserving judgement until the new caps come and I do the replacement, but it looks like your description of the failure mechanism is right--the heavier components are cantilevered off the board, held by cement. Ultimately vibration and bumps cause them to pull the foil from the board and open it. It amazes me that Mitsubishi was able to make this on a two-layer board. I expected a four-layer board. Larry Hopefully thats your problem. Although if the caps aren't leaking or bulging, you could repair the trace and fire it up for a quick test. How would you know it was working ? Check the diagnostic output pin for pulsed signal. Good Luck > Well, I was baffled by this for quite a while. The ohmmeter (one of those > business-card-sized digital units) indicated continuity (beeps) on all the [quoted text clipped - 24 lines] > > Larry I replaced the four electrolytics today. There was brown crud under two of them. Either the adhesive they use is corrosive (as you suggest), or the electrolyte is leaking and corrosive. While I had the big one out that's near the connector (50V, 47uF), I looked further for the open circuit. I never could see it, but I located where it had to be and repaired it. The main trace comes in with 12 volts on two adjacent pins. This trace goes through a T-filter. The next via on that 12-volt trace is a reverse-biased diode to ground, to protect against reverse polarity (car battery installed backwards). Using a real analog VOM (not the beeper) I found continuity from the 12 volt connector to through the filter, but not to the diode. It looked like there was corrosion around the filter lead. So I took a short piece of AWG 18 wire and bridged from the filter to the diode and suddenly 12v and 5v appeared in the right places. Had I thought to look here first, I would have also checked the diagnostic output. It's back in the package now, so I'll just install it and try it tomorrow and report back. Thanks a lot, Nirodac. Just to finish the story, I installed the computer today and the car started right up and runs fine. It is more than wishful thinking that the car actually runs better than before the failure. I expect there may have been some noise due to caps going bad that was affecting engine performance above 4000 RPM. It now winds smoothly to 6000 (not something I do very often--I'm nearly 60 years old). Nirodac, thanks a lot. If you see this, drop a note to the Hotmail account listed above. Larry Marks GSR4 =GSX? > Just to finish the story, I installed the computer today and the car > started right up and runs fine. [quoted text clipped - 9 lines] > > Larry Marks You're right, I got a constant signal. This is what I meant by having no signal. Sorry for the misunderstanding. I am in fact checking only the ECU and it's wiring. Biggest problem is that I could not find a replacement which I can afford (a new unit costs about $1000 and I bought the car for $2200) and that's why I have to fix my unit, if possible. I really appreciate your help. > After repairing the ECU, it seems I got sparks and fuel pressure, because I can hear & feel a repeately short combustion as long as I keep trying to crank it. > My mechanic friends are saying the injectors are not pulsed by the ECU. (I'm a software developer, so I believe them) You better bet the injectors are pulsed by the ECU! (I'm a computer scientist and a) don't belive my mechanics friends because we're talking about electronics here, b) wonder what else might pulse the injectors besides the *engine control* unit and c) know better, check the ECU pinouts: http://www.vfaq.com/mods/ecu-harness-1G.html vfaq.com has many more on Mitsubishis...) Norman I've read almost all on vfaq... great link, thanks. Sorry again for a misunderstanding: the mechanics were saying that there's no pulse to the injectors, but should be. This is what I meant by "injectors are not pulsed by the ECU". Since I don't have an osciloscope available, I could not check if there is pulse or not, but I believe the mechanics and the question is why. The board didn't show any fault after the first repair, so I've double checked all the harness wiring. Later, I've removed 5 transistors: - first 4 are connected to GROUND (pins 101 & 106) and each injector (pins 51,52,60,61), but using a MUT, they all seem to function correctly - the 5th one is connected to Power Supply (pins 102 & 107) and many components on the PCB, including the EPROM This one is not giving response to a MUT and I believe was damaged. Shops arround are not having it in stock. No equivalent available, too. The weird part is that I'm getting power to all injectors, but GROUND. Would've make sense if first 4 MOSFETs (transistors) were connected to power and the fifth to GROUND. I'll try making the scheme of the board using Visio or something. This is becoming more complicated than I thought. Thanks for all your input. Talk soon, Bogdan > I've read almost all on vfaq... great link, thanks. > Sorry again for a misunderstanding: the mechanics were saying that there's no pulse to the injectors, but should be. [quoted text clipped - 4 lines] > - first 4 are connected to GROUND (pins 101 & 106) and each injector (pins 51,52,60,61), > but using a MUT, they all seem to function correctly > - the 5th one is connected to Power Supply (pins 102 & 107) and many components on the PCB, including the EPROM > This one is not giving response to a MUT and I believe was damaged. > Shops arround are not having it in stock. No equivalent available, too. Which component deliveres the input signal to this transistor. Is it directly connected to a processor pin or can you find a driver circuit for it? Can you give us the type of transistor you are looking for? I dont see that it should have specs which could not be handled by any modern standerd PWR transistor. > The weird part is that I'm getting power to all injectors, but GROUND. > Would've make sense if first 4 MOSFETs (transistors) were connected to power and the fifth to GROUND. [quoted text clipped - 3 lines] > Talk soon, > Bogdan > I've read almost all on vfaq... great link, thanks. > Later, I've removed 5 transistors: > - first 4 are connected to GROUND (pins 101 & 106) and each injector (pins 51,52,60,61), > but using a MUT, they all seem to function correctly > - the 5th one is connected to Power Supply (pins 102 & 107) and many components on the PCB, including the EPROM > This one is not giving response to a MUT and I believe was damaged. > Shops arround are not having it in stock. No equivalent available, too. What is the part number? I could probably suggest a good replacement... > The weird part is that I'm getting power to all injectors, but GROUND. > Would've make sense if first 4 MOSFETs (transistors) were connected to power and the fifth to GROUND. > I'll try making the scheme of the board using Visio or something. > This is becoming more complicated than I thought. > Thanks for all your input. Not that complicated :) it is a very common arrangement, the injectors are all supplied 12V from the main MPI relay and those 4 transistors switch the other side of each to ground to pulse them.. The fifth transistor is part of the main +5V regulator for the ECU i believe... I have one of these ECUs in my car, did the caps a couple of years ago but I may pull it out again to familiarise myself with it :) -Richard (electronics tech) Hello, I am having similar trouble except my injector stays on. (does not pulse) I took the top of the ECU off and tested the unit. I found that the 1 black transistor just after the plug is always showing numbers with a ohms meter. Can these be replaced and if so would you know where I can buy one and the numbers off it? Thank you, Joe >> I've read almost all on vfaq... great link, thanks. > [quoted text clipped - 23 lines] > >-Richard (electronics tech) >Hello, >I am having similar trouble except my injector stays on. (does not pulse) I [quoted text clipped - 11 lines] >> >>-Richard (electronics tech) guys i also have same problem as of now, i already replace all the capacitors and resistors, my problem is signal that goes to the MPI (relay) coming from the ecu, the fuel pump wont start even when cranking, so i need to tap directy the fuel pump to a 12v supply so that the engine will start.aside from that everything seems to be fine, what do you think is the problem? thanks |
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