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Car Forum / Honda Cars / March 2007The D4 light
I seem to have a D4 light which sometimes is on (solid) and other times is not on. At first I thought the LED was failing but then in the service literature it appears that D4 is used as a TCU diagnostic readout. Do you think the TCU is trying to tell me something? From online reading it seems that the "S" light would be lit in the case a code was stored... The transmission works fine, under load sometimes it upshifts at higher RPM than it should, and when shifting under load it flares (this is most obvious on 4-3 downshift), but it never slips out of gear or fails to go into gear. > I seem to have a D4 light which sometimes is on (solid) and other > times is not on. At first I thought the LED was failing but then in [quoted text clipped - 7 lines] > (this is most obvious on 4-3 downshift), but it never slips out of > gear or fails to go into gear. Year? Model? Engine? Mileage?  SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > "runde...@mail.win.org" <runde...@mail.win.org> wrote innews:1173106724.653803.96500@t69g2000cwt.googlegroups.com: > [quoted text clipped - 11 lines] > > Year? Model? Engine? Mileage? I'm sorry, it's a 90 Accord EX, 2.2 SOHC, 200k. >> "runde...@mail.win.org" <runde...@mail.win.org> wrote innews:1173106724.653803.96500@t69g2000cwt.googlegroups.com: >> [quoted text clipped - 11 lines] > > I'm sorry, it's a 90 Accord EX, 2.2 SOHC, 200k. ======================================= How many times have you changed the tranny fluid, and was the correct Honda fluid used? 'Curly' > How many times have you changed the tranny fluid, and was the correct > Honda fluid used? The fluid is old. The tranny needs to be flushed. The car sat for a long time and the motor was repaired. I put a bottle of Lucas in it after the motor repair to get it by. I am not that concerned about the rough shifting in and of itself. I am more curious about what would the D4 light being solid on some of the time (i.e. normal), and sometimes completely off. Seems like it should be flashing if there's actually trouble, or the S light would be on. I tried "wiggling" the shifter but it doesn't seem to be intermittent. The tranny behaves the same no matter what the state of the light is. Maybe it's just a flaky LED in the dash cluster? >> "runde...@mail.win.org" <runde...@mail.win.org> wrote >> innews:1173106724.653803.96500@t69g2000cwt.googlegroups.com: [quoted text clipped - 14 lines] > > I'm sorry, it's a 90 Accord EX, 2.2 SOHC, 200k. In your car the "S" light is used as a diag tool. Your D4 light problem is likely a flaky connection somewhere, probably at the shift lever. This *may* also account for the odd shifting behavior. However... You have 200K on the tranny, and old fluid. Failure to change the fluid will cause irreparable damage to the clutches and hydraulics of any automatic. In your case, Dexron-III is OK, but Honda ATF-Z1 is better. I would have the fluid drained and refilled at least three times with Honda ATF-Z1. If the transmisison isn't in too bad shape, this may be enough to cure your flaring problem. If it does not, then you have severely worn clutch packs, or sticking solenoids. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > You have 200K on the tranny, and old fluid. Failure to change the fluid > will cause irreparable damage to the clutches and hydraulics of any [quoted text clipped - 4 lines] > cure your flaring problem. If it does not, then you have severely worn > clutch packs, or sticking solenoids. Yeah, I plan to have it flushed via machine and obviously to use the correct fluid. This question was more trying to figure out if I also have a TCU gremlin to deal with... I'll check that harness at the shifter next time I have that apart. I actually just had it apart to lube the shifter rod and the park pin. > Yeah, I plan to have it flushed via machine and obviously to use the > correct fluid. DO NOT FLUSH IT!!! Drain and refill with Honda fluid at least 3 times. >> You have 200K on the tranny, and old fluid. Failure to change the fluid >> will cause irreparable damage to the clutches and hydraulics of any [quoted text clipped - 10 lines] > shifter next time I have that apart. I actually just had it apart to > lube the shifter rod and the park pin. NONONONO Noooooo. Do NOT have it flushed. Have it drained and filled, 3 times, with about a week between each time. > NONONONO Noooooo. Do NOT have it flushed. Have it drained and filled, 3 > times, with about a week between each time. Interesting. The gospel I've always been handed is that a drain and refill is the wrong thing to do. The explanation was that changing the fluid would renewing the detergents, which slowly dislodges the crud that is built up in the transmission, which then clogs the filter and starves the pickup. (Which is the point of "transmission fix" products, to bring back the viscosity of the fluid without adding new detergent.) The flush, if done properly through the pickup instead of the cooler lines and using fresh tranny fluid and not solvent, would get rid of all the old fluid AND crud, to essentially reset the fluid to a known state. Maybe the hole in this, and why everyone is recommending repeated short term fluid changes, is that the crud gets dislodged too slowly for the flush to actually clean anything out, so it's really no different than a one-time fluid change, which is a big mistake on a neglected tranny. It would be interesting to see what the factory repair manual recommends, or maybe the 3-time change actually is what they recommend, anyone know? >> NONONONO Noooooo. Do NOT have it flushed. Have it drained and filled, 3 >> times, with about a week between each time. [quoted text clipped - 19 lines] > recommends, or maybe the 3-time change actually is what they > recommend, anyone know? That's exactly what is recommended by Honda. Also note that your Tranny does not have a serviceable filter. Just drain and refill 3 times, and you will be fine. >> NONONONO Noooooo. Do NOT have it flushed. Have it drained and >> filled, 3 times, with about a week between each time. [quoted text clipped - 4 lines] > crud that is built up in the transmission, which then clogs the filter > and starves the pickup. Your transmission is likely already on its last legs and will fail soon. You have little to lose by trying this. > It would be interesting to see what the factory repair manual > recommends, or maybe the 3-time change actually is what they > recommend, anyone know? The drain-and-fill-three-times IS the factory recommendation. You are supposed to drive the car briefly between each drain and fill. The multiple fill/drive/drain sequence compensates for the fact that the torque converter has no drain. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > Your transmission is likely already on its last legs and will fail soon. > You have little to lose by trying this. Well, if the drain plug is not full of metal I think it should be okay. A "new" used transmission isn't that much anyway, freight costs more than the tranny. Is it possible to drop the tranny out the bottom as a shortcut? > The drain-and-fill-three-times IS the factory recommendation. You are > supposed to drive the car briefly between each drain and fill. What is "briefly"? Mileage? Stay off the highway? >> Your transmission is likely already on its last legs and will fail soon. >> You have little to lose by trying this. > > Well, if the drain plug is not full of metal I think it should be > okay. Clutch lining material does not stick to magnets. > A "new" used transmission isn't that much anyway, freight costs more > than the tranny. Is it possible to drop the tranny out the bottom as > a shortcut? That's the accepted way of removing a transmission. No need to pull the engine too. >> The drain-and-fill-three-times IS the factory recommendation. You are >> supposed to drive the car briefly between each drain and fill. > > What is "briefly"? Mileage? Stay off the highway? Long enough for the fluid in the torque converter to mix with the new fuid in the pan. Once around the parking lot should do it. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > > Well, if the drain plug is not full of metal I think it should be > > okay. > > Clutch lining material does not stick to magnets. True, but then I should see it floating around IN the fluid, either way the evidence should be visible. > > What is "briefly"? Mileage? Stay off the highway? > > Long enough for the fluid in the torque converter to mix with the new fuid > in the pan. Once around the parking lot should do it. So then I can get the whole thing done in an afternoon. Now to find a nice deserted parking lot since my landlord doesn't allow car repairs... >> > Well, if the drain plug is not full of metal I think it should be >> > okay. [quoted text clipped - 3 lines] > True, but then I should see it floating around IN the fluid, either > way the evidence should be visible. It sort of is. That's what makes the fluid black. Should you start finding chunks or fragments in the fluid, the tranny's *really* pooched. >> > What is "briefly"? Mileage? Stay off the highway? >> [quoted text clipped - 4 lines] > nice deserted parking lot since my landlord doesn't allow car > repairs... I had the same problem when I lived in an apartment. I understand the landlord's reasoning, but it still makes things more difficult. And you do know how to check the fluid level in a Honda AT, do you? It's not the same as most cars. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > It sort of is. That's what makes the fluid black. Should you start finding > chunks or fragments in the fluid, the tranny's *really* pooched. Well, the fluid isn't black, it was still clear on the dipstick, just more brown than red. Of course it's hard to tell what's going on just from the dipstick. > And you do know how to check the fluid level in a Honda AT, do you? It's > not the same as most cars. I checked it with the motor running after a short drive like my other cars, but from your comment I'm guessing that's the wrong thing to do. I made sure that the rubber seat of the dipstick "popped" back in so the level would not be wrong. I didn't care so much about the exact level as the condition of the fluid at the time, since it had not been driven for quite a while and previous owner probably neglected it. >> It sort of is. That's what makes the fluid black. Should you start >> finding chunks or fragments in the fluid, the tranny's *really* [quoted text clipped - 3 lines] > more brown than red. Of course it's hard to tell what's going on just > from the dipstick. As I said before, a fluid change may not help your issue here, but it certainly won't hurt. This is a cheap first-effort before looking for more difficult stuff. I'm suspecting you have deeper problems inside the transmission, either sticking solenoids, or a sludged valve body. >> And you do know how to check the fluid level in a Honda AT, do you? >> It's not the same as most cars. [quoted text clipped - 5 lines] > level as the condition of the fluid at the time, since it had not been > driven for quite a while and previous owner probably neglected it. You SHUT THE ENGINE OFF, then check the level within one minute of shutting the engine off. Honda is different. What can I say? SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > I'm suspecting you have deeper problems inside the transmission, either > sticking solenoids, or a sludged valve body. Here is something I didn't mention before (because I wasn't really trying to "solve" the transmission problem, just wondering about the dash LED). If I stomp on the pedal to where a load based downshift would be imminent, but then manually shift down into third while keeping the throttle open, it doesn't flare up. Isn't that strange? > > I checked it with the motor running after a short drive like my other > > cars, but from your comment I'm guessing that's the wrong thing to [quoted text clipped - 7 lines] > > Honda is different. What can I say? Well that's good to know. They should print things like that on the underhood label instead of burying it in the owner's manual, IMO. >> I'm suspecting you have deeper problems inside the transmission, >> either sticking solenoids, or a sludged valve body. [quoted text clipped - 4 lines] > would be imminent, but then manually shift down into third while > keeping the throttle open, it doesn't flare up. Isn't that strange? Nope. It narrows things down. You almost certainly have a bad shift solenoid. A problem like this is supposed to make your "S" light blink, but I guess that doesn't always happen. jim beam rigged something up recently that allowed him to observe the solenoids in operation. >> > I checked it with the motor running after a short drive like my >> > other cars, but from your comment I'm guessing that's the wrong [quoted text clipped - 11 lines] > Well that's good to know. They should print things like that on the > underhood label instead of burying it in the owner's manual, IMO. Especially when the other 99% of cars on the road are different from that. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ >>> I'm suspecting you have deeper problems inside the transmission, >>> either sticking solenoids, or a sludged valve body. [quoted text clipped - 8 lines] > solenoid. A problem like this is supposed to make your "S" light > blink, but I guess that doesn't always happen. Hold on now... I've spent some time with the shop manual here trying to make some sense of this. You mentioned flaring on up and downshifts, specifically 3-4 and 4-3. This is critical to diagnosis, so I hope you've been complete in your description. One major difference between the shift from 3 to 4 is Shift Solenoid "A" turns off going up, then turns back on again going down. Solenoid "A" is off when the car is at rest in Drive. It turns on again for Reverse, so if you have no delay when shifting to Reverse, Solenoid "A" is surely fine. However, the shop manual lists these things as possibly being wrong: 1) Throttle cable adjusted too long (probably not the case here, but worth checking because it's cheap) 2) Vacuum modulator valve stuck (not the case here) 3) Orifice Control Valve stuck (possible; also accounts for harsh upshift) 4) Feedpipe O-ring broken (not the case here) If the Orifice Control valve is stuck, this is due to sludge and neglect. It is also possible the 3-4 shift valve is sticking. This is inside the main hydraulic valve body. With my copy of the manual, I can't tell if you bypass the Orifice Control Valves when shifting manually. Also, there are line pressure inspection bolts on the side of the transmission. These can be removed and a gauge plumbed in so line pressures can be monitored as-it-happens. If you've got a slow pressure buildup and release to 3rd/4th parts (which is what appears to be happening here), this will become apparent when measured. Honda automatics haven't changed substantially since 1990, so if you bring the car to your local dealer, the techs there will have a pretty good idea what to do and will have the necessary testing equipment. Good luck. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > You mentioned flaring on up and downshifts, specifically 3-4 and 4-3. This > is critical to diagnosis, so I hope you've been complete in your > description. No, it flares into third under load, whether on upshift (2-3) or downshift (4-3). If I ease up on the throttle when the shift is about to happen it does not flare. I haven't noticed any other transmission anomalies besides what feels like late shifts in general. > It turns on again for Reverse, so if > you have no delay when shifting to Reverse, Solenoid "A" is surely fine. Yeah, reverse seems fine. > However, the shop manual lists these things as possibly being wrong: > 1) Throttle cable adjusted too long (probably not the case here, but worth > checking because it's cheap) Eh, it's possible. Remember I had this thing ripped to shreds not too long ago. But I don't know what the throttle cable could have to do with it, the ECM sees the TPS position and the transmission sees manifold vacuum, so how does the cable adjustment change that? > 2) Vacuum modulator valve stuck (not the case here) Actually, it does kind of act like an open modulator in that the shifts are late, I couldn't find any vacuum leaks by a quick check though. > Also, there are line pressure inspection bolts on the side of the > transmission. These can be removed and a gauge plumbed in so line pressures > can be monitored as-it-happens. If you've got a slow pressure buildup and > release to 3rd/4th parts (which is what appears to be happening here), this > will become apparent when measured. Oh, that's interesting. I assume those specs are in the manual. What is the title/number of the manual you are looking at? <snip> >> However, the shop manual lists these things as possibly being wrong: >> 1) Throttle cable adjusted too long (probably not the case here, but [quoted text clipped - 4 lines] > with it, the ECM sees the TPS position and the transmission sees > manifold vacuum, so how does the cable adjustment change that? TPS reading is entirely dependent on throttle cable movement. If the cable is out, the TPS will receive incorrect readings (example: pedal hits floor, throttle still not completely open). Seems to me this would be manifest in any gear though, the reason I don't think it's the issue here. >> 2) Vacuum modulator valve stuck (not the case here) > > Actually, it does kind of act like an open modulator in that the > shifts are late, I couldn't find any vacuum leaks by a quick check > though. The modulator is only ONE factor. Are ALL shifts late, including Reverse? If not, the modulator is fine. >> Also, there are line pressure inspection bolts on the side of the >> transmission. These can be removed and a gauge plumbed in so line [quoted text clipped - 4 lines] > Oh, that's interesting. I assume those specs are in the manual. What > is the title/number of the manual you are looking at? I'm looking at a copy of the Helm manual for '89-'91 Accord. Problem is, I have to pair that with my original '91 Integra factory manual because the generous dummy that copied the Accord manual for me neglected to include ANY indices, most of the wiring diagrams, and a bunch of other pages he figured weren't really that important. I guess he did this to save time. He's not a mechanic, of course... Another problem is that the hydraulic diagrams are small, busy and dense, plus containing a generous salting of legal-notice-size 6pt type, not easily photocopyable. And the 'Teg's hydraulics are a little bit different from the Accord's. The Integra's AT is very similar to the Accord's, differing primarily in manual gear selection choice, and in the inclusion on the Accord of a "linear solenoid", something the 'Teg doesn't have. The one thing that overwhelms me while attempting to comprehend this, is the crushing, brain-busting complexity of the whole electronically- controlled automatic transmission idea. The hydraulics are bad enough, and then you have to layer the electrical control on top of that, plus all the sensors the TCM and ECU depend on. Well, the basic concept of the tranny is pretty simple, but how Honda actually goes about making the beast work is frankly boggling. How long did it take them to come up with this? How many times did the manual's artists and writers have to go back to the engineers before their diagrams and text were correct? Do I really wanna know? A manual tranny is almost caveman-like in its simplicity and crudity: you have a man in the driver's seat stirring a big stick around. By contrast, in an auto tranny you have a computer stirring the big stick. But...the computer, lacking eyes, ears, fear, wife in the passenger seat or mother-in-law in the back, has to be able to figure out on its own exactly what needs to be done in the very next instance, every time. It's a hard job. A final note I forgot before: The TCM (Transmission Control Module). These are known to go bad and this can account for all your symptoms, including the lack of trouble codes. You can get replacements for about ten or twenty dollars at the wreckers. Might be worth a shot. Do you wonder now why good techs are paid what they're paid? SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > TPS reading is entirely dependent on throttle cable movement. If the > cable is out, the TPS will receive incorrect readings (example: pedal > hits floor, throttle still not completely open). Seems to me this would > be manifest in any gear though, the reason I don't think it's the issue > here. Oh right, I get what you meant now. > The modulator is only ONE factor. Are ALL shifts late, including > Reverse? If not, the modulator is fine. No, seems to go into reverse at the right point. > The one thing that overwhelms me while attempting to comprehend this, is > the crushing, brain-busting complexity of the whole electronically- > controlled automatic transmission idea. The hydraulics are bad enough, > and then you have to layer the electrical control on top of that, plus > all the sensors the TCM and ECU depend on. Yeah, the layman tends to assume that the engine of a car is the most complex system but modern A/T's seem to have claimed that title. It's amazing how reliable they are, on the whole. > A final note I forgot before: The TCM (Transmission Control Module). > These are known to go bad and this can account for all your symptoms, > including the lack of trouble codes. You can get replacements for about > ten or twenty dollars at the wreckers. Might be worth a shot. Yeah, I was going to check into that. Looks like leaking caps are pretty common on this one... |
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