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Car Forum / Mercedes-Benz Cars / September 2004W140 / 1992 500SEL Instrument Panel Malfunction
Hi all, Ive developed a serious electrical malfunction in my instrument panel. All the lights are going crazy and all the guages are dead. Otherwise the car is operating as normal. the dealer recommeds changeing the cluster, but I would like to see if its not some relay somewhere? I checked all the fuses, all are OK. I have a link to my website which has a 1Mb clip displaying the problem : http://www.chargerr.com/BENZ2.HTM Anyone know what may be the culpret, or how to remove the cluster? Thanks! Jim I think it is a possibility that you just have a ground problem... pull the cluster out and loosen the grounds where all those brown wires attaches to the body metal... examine... make sure there is positive bare metal contact (not over paint)... and retighten. >I think it is a possibility that you just have a ground problem... pull the >cluster out and loosen the grounds where all those brown wires attaches to >the body metal... examine... make sure there is positive bare metal contact >(not over paint)... and retighten. Thanks for the info Tiger! I will check it out tomorrow when im not so tired, and let you know. I spent the whole night getting that damn cluster out. Turns out it just needed a little shove from behind. Now I gotta screw back all the things I took out trying to clear space! Anyhow, I took the cluster apart, the circuit board seems fine, there are no obvious burn marks or charred bits. So brown wire should indicate ground, ,Ill check that out. Barring that ill need to find out what each pin on the 4 connectors are expecting and try reproducing the light show on the bench. Jim On Thu, 26 Aug 2004 02:49:15 GMT, jimbobeleeeeeoooooooooooeo Tiger, I inspected all the browns, and yes all solid browns go to ground. They seem visually solid, and resistance seems correct. I am left with the possibility of a power source issue. When I rig up power and ground to the cluster on the bench, ,the lights are all solid, so Im gonna go with a power problem. Unfortunately I have no pinout or spec or cd to get more info. anybody have a pinout handy? I did some searching on MB other forums and there was a guy with a simiular problem to mine. He also had his car sitting for a while, and when he tried firing it up-dead cluster. Another user gave this recommendation : "Hi, check the fuse in the top of the overvoltage protection relay, located in the firewall at the base of the windshield, it could have blown during the jump. Sounds like a bad (i.e. corroded) ground, though. Check the fuses in the fuse box: some of mine were corroded on the ends where they make contact and acted as if they were blown. I will research and pass anything else along." Anybody know where this fuse is on the fusebox? I dont read german! Anything helps! Jim > On Thu, 26 Aug 2004 02:49:15 GMT, jimbobeleeeeeoooooooooooeo > Tiger, I inspected all the browns, and yes all solid browns go to [quoted text clipped - 5 lines] > Unfortunately I have no pinout or spec or cd to get more info. anybody > have a pinout handy? Actually it looked to me like some sort of computer failure mode display? Perhaps your instrument panel is fine, but is trying to tell you something? Can you check the code status of the vehicle? Marty I would then change the fuse for the instrument cluster... german is not so far from english in some words... and you can also use babelfish to translate. http://babelfish.altavista.com/ >I would then change the fuse for the instrument cluster... german is not so >far from english in some words... and you can also use babelfish to >translate. > >http://babelfish.altavista.com/ Hi guys, thanks for the support thus far. Sorry been busy at work and furiously trying to debug this bastard. I think I have finally hit on the suspect. A faulty voltage regulator on the circuit board. Im going to the local electronics store tomorrow to verify my findings and test out a solution. I have tested the fuse, it seems OK. Also I found out if you flip the german side over, there is English! Also, the grounds seem solid against the chassis, and no other malfuntion is present. I was able to reproduce the problem on the bench. Lastly, the dealer wants $1500 for a new cluster + P&L&Tax. Wouldnt it be funny if a $2,000 job turns out to be equivilant to a $0.50 component? Local parts supplier wants $600 for a used piece or a "refurbished" piece. After talking to the dealer and finding out this is not an uncommon failure for the W140, im starting to think VCR repairmen are on to this.... Follow the money, as they say.... Ill let you know my findings... > Follow the money, as they say.... > > Ill let you know my findings... Hmmm, I am also an electronics tech... Keep us posted. Marty >> Follow the money, as they say.... >> [quoted text clipped - 5 lines] > >Marty OK, Im back and with mixed news. I have it working again, dropped it in the car and everything is good. I wanna drive it around for a while before I can honestly say the thing is fixed. But no more christmas tree light show, so thats good. Ive attached a picture of the circuit board (back of the cluster), which shows the top view of a 2 layer printed circuit board. The long white wire is my kludge. It feeds the new voltage regulator on the left. Also 3 of the capacitors are new. The problem is that the regulator was not giving voltage to the rest of the circuit. If you spec out the datasheets on a few of the ICs on board you'll find that the board uses a combination of voltages from 1 to 9V. The regulator I replaced was an 8.5V regulator, which is very uncommon, and perhaps one of the reasons why it broke. There is some bizarre fucken circuit here. The transistor that feeds the regulator wasnt giving the right voltage which would not power the board (even if it was working). So I force fed the board an external 6V power supply and everything started working, even the transistor that fed the regulator. This is a sort of chicken vs egg problem in engineering. The regulator needs to power the circuit which turns itself on. This is so f.cked. I would get fired if I built something like this. Anyhow, ,i tried to trace the bastard but was running into loops, where was the source of the problem I dont know? The reason why it was flashing like it was, was because the regulator was leaving the board undriven, so the nearest power source was driving things. And that was the seatbelt warning flash. Actually that seatbelt flash was flashing the whole cluster, and it was stuck in an indeterminant state, which just flashed. Anyway my solution was to take the accessory feed from one of the bulkheads and power the new regulator directly. I had my hand on it for half an hour and it didnt even get warm, so Im claiming this one a victory for the people. Without anything resembling a schematic, I dont think I did too bad. Car fired up and everything is good. now time for sleep. Anyhow the moral of the story is, dont think this is only for the W140. VDO, a german auto electronics manuacturor put their name all over this bitch. And along with discontinued ICs, put untraceable mixed signal logic all over. If they did it for W140, they probably did it for everyone else. Im guessing that my cluster went awry long before the light show came along. I wonder how many other intermittent problems Ive had will go away. Marty, good look debugging this thing if it ever happens to you! I know I did not find the problem. I also know there are "remanufactored" instrument clusters out there in the wild, along with $1500 OEM pieces. And I guarentee that there are no VCR repairmen out there who can trace this thing if I cant. Im putting 2 and 2 together and guessing that someone else came up with the same solution I came up with, and buying 50 cent regulators and unnaturally long wires, are trying to put their kids through college. Dont buy "reman" electrical devices, and.... Moral of the story : dont buy a mercedes. Anyone wants my car lemmeknow http://www.chargerr.com/BENZ.HTM Tired and disgruntled MB owner. > Moral of the story : dont buy a mercedes. Actually the moral of the story is that if you can't afford to maintain these expensive and complex cars you shouldn't own one. h >> Moral of the story : dont buy a mercedes. > > Actually the moral of the story is that if you can't afford to maintain > these expensive and complex cars you shouldn't own one. Actually I think Jims point is that the electronics in his car are an embarrassing bunch of crap. Can you afford to pay for an embarssing bunch of crap? You can? Oh. My take on this has always been to buy the older vehicles with less complex electrical accessories. I like manual systems where possible (seats etc.) as they give me less thing to break. I have over the years troubleshot many problematic systems including Fiat fuel injection and lovely lucas (Lucas last words? Don't drive at night) in all flavors of British cars and many classic american cars. It's surprising that the VDO instrumentation setup in such a high end vehicle would be such a complete hack design wise, but maybe it was just a bad year? Then again, although I could "afford" a newer car, I am notoriously cheap. Still Jims car sure does look like a sweet ride... Marty >>> Moral of the story : dont buy a mercedes. >> [quoted text clipped - 3 lines] >Actually I think Jims point is that the electronics in his car are an >embarrassing bunch of crap. Hey Guys, Well Ive booted around in my car for the last couple days and seems everything is working except for the fuel guage. As a result the economy meter is screwed too. I guessing I could further try to pinpoint the problem by examining where in the circuit the fuel is giving a signal. ...but since I dont have a schematic, nor will I ever. Its off to MB to give them more of my money. Harvey's comment made me think. You know, hes right. You gotta spend the big bucks. Even with my 1992, I still get letters from MB telling me about their fall service specials with more information on all the new models etc. And it seems like in these fliers, everybody plays golf... and the seasons are all fall... and everybody dresses in busines casuals. But thats funny. I dont imagine that old guy with the grey vest ever taking apart his dash to try to debug a malfunctioning 8.5V discontinued voltage regulator. Thats the dealers job. And his secretary takes care of billing to his credit card. You know. I dont think MB EVER intended for these (W140) cars to ever fall in the hands of the commoner. I've been trying to sell my car since february, and have had no luck. Ive dropped the price to even BELOW black book "parts-car" value, and still havent had even a single person to come and look at it. I have only had used car dealers calling me up and offering me peanuts for the car. You know one guy actually called me up and offered me $10K for my car. And he was insulted when I laughed at his offer. I paid $50K for this bitch 4 years ago. And with insurance and repairs, ,ive sunk into this little baby almost $65,000. I pray to see maybe $15K of that ever again. Harvey, you are absolutely right. You gotta pay to play. The MB game is to have people with a HELL of a lot of money come buy their cars and live the dream. Well at least for 4 years uuntil the warranty runs out and the car starts having problems. But that will never happen. MB helps extrract money from the rich old white guy in exchange for the prestiege and honour of driving the best car on the road. Its for people who actually need help to create a stream of outward money flow from their wallets to somebody...say MB. The service manual for the S, CLK, CL are not available to the public. MB only recently released the S to the public. A mere 12 years aftfer the model first was released. I guess their cash cow wasnt producing enough milk, so they decided to give the people a break. I dont think MB ever dreamed that their cars would ever depreciate. Their probably scratching their heads trying to understand what God's plan was to have these motherf..kers depreciate so low. Now dont get me wrong. This is the best car I have ever driven. It is over-engineered to last forever. Its 10x more car then one could possibly need. So im going to gracefully bow out and let the rest of the obviously rich owners of all these cars help drain money from themselves in exchange for the dream. The brutal reality that sets in when you realise the dream is just a dream, and nothing tangeable is left when the money is gone, is enough of a lesson for me. Ill never fucken buy a Mercedes again. Pardon me....you guys have fun. Someone please help me reclaim some of my investment! Jim |
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