R129 - Serious electrical problem… grounded until fixed!

[Rud]

The electric system has just gone berserk. It started some time ago, when activating the turn signal, all laps in the instrument cluster blink ones, and power to the radio and navigation disappeared for at few seconds. This happen a few times, but with weeks in between.
Then the other day, a new strange thing happened. Suddenly the ASR and ABS lamp was constant on, and every time I pressed the break pedal the roll bar lamp turned on to, as long the breaks was activated.
Then yesterday it culminated. Nothing works in the instrument cluster. No instrument indications of any kind, except that all lamps are blinking. Strangely enough, when I flip the turn signal arm the blinking stops, but the turn signal lamps don’t light up. The indoor light at the top of the windshield doesn’t work either, but the ones in the doors are blinking every time I flip the turn signal.
I have checked all the fuses, both in the front and in the trunk. And I have moved them forth and back, just to make sure there are connections.
So, what’s next? Any idea where to look for a broken connection, bad relay or ground connection, controller unit… anyone else that have experienced the same strange behavior, and knows what to do?
Rud

[waybomb]

I had all sorts of goofy electrical issues when my OVP failed. Maybe the OVP?

[tecqboy]

Possible bad voltage regulator on VDO ( cluster )? Search the forum on "capacitor" and cluster / VDO. There is a capacitor which fails and causes some of the problems you listed.

[Rud]

Originally Posted by tecqboy

Possible bad voltage regulator on VDO ( cluster )? Search the forum on "capacitor" and cluster / VDO. There is a capacitor which fails and causes some of the problems you listed.

Thanx tecqboy ... If it turns out that it isn't the OVP fuse or OVP itself, and a general reset doesnt fix the problem, I will start look for that hit. As a matter of fact, I have to have the cluster out anyway, because the bulb for the outside temp are dead. Wonder if these 0,75w bulb can be replaced with LED's instead.

Rud

[Rud]

Somewhere else I saw a statement from you, that 200.000 miles i near the end of the R129 engine. Mine has run for 156K miles, and is perfect. No oil loss etc… except I have to replace the distributors and rotors. It's common over here to say, that a Mercedes engine is worth 625K miles… I hope you're not correct in your statement ... I just love that car

[tecqboy]

I don't believe I've ever made a statement in the forum regarding the life expectancy of a Mercedes engine. I have no personal experience to make those judgements. On my '91 129, the OVP is under the hood on the right side near the fire wall under the plastic weather seal which covers the electronic modules. I believe there are 4 or 5 screws to be removed to gain access.

[Rud]

Originally Posted by tecqboy

Possible bad voltage regulator on VDO ( cluster )? Search the forum on "capacitor" and cluster / VDO. There is a capacitor which fails and causes some of the problems you listed.

Hi tecqboy,
Found this site: http://www.mbcluster.com/FAQPage.htm and will try to do some testing in the weekend. I have already done the build-in cluster test and everything looks okay. Now I will test the voltage on the connectors. Only problem seems to be that the fault is temporary, which makes it harder to find.
Also the capacitor issue has to be checked before I reach the conclusion, and all too expensive, replacing the harness.
Thanx for the advice

[nulu]

Check your brake light bulbs , if i remember correctly on a 140 s class, the wrong single contact brake light replaced with a double caused a similiar
problem as yours , ive seen a wackey problem with front turns signals too, just a thought.

[Rud]

nulu, will do asap... but I thought i would get at bulp missing light in the cluster....

Thanx for the advice... thats the easy one, except if it turns out the cable to the break lamp is the fault. But at good hit.

Claus

[Rud]

I have managed to get things back, to almost normal, twisting all fuses ones again. Now, only the ASR and ABS lamp is on and the top can't open.

I have tried to locate the OVP, but without succes. Under the alu cover the are four 10A fuses, all okay as well. But the OVP, really can't find it.

There use to be a item locator at www.classic-roadster.de, but that site has been down for quite awhile. Anyon know if this has been moved to somewhere else?

Rud

[Rud]

tecqboy.. thanx again... has slipped my mind, but since I'm not the most qualified car technical person, just trying to understand og not to forget, saving money, I would love to get these issues locallized before I contact my indy, and get his help to fix the problems.

Already now, he tells me that I know more about the car than he does. But still he's the one to get durty hands... :-)

I know for at fact, that I had one of the ABS sensores replaced 3 years ago. Maybe its time for the next one...

Claus

[Rud]

CCW you’re my friend… hmm.. the motor harness. Yes for what I know it’s the original. Only pleasing factor is, that it will only cost me a fraction of what the car is worth in this country. Guess its worth replacing. A 16 year old car like the one I have is sold for around DKr 350.000 = $ 53,850 in this country these days, so the harness is a relative small cost compare to that. Still… argh!

[kbdixon]

Search parts on this site for the best price it is where I got mine.

[Rud]

Originally Posted by kbdixon

Search parts on this site for the best price it is where I got mine.

Only problem by buying from the states is, that I have to add 25% sales tax and custom on it. Unless.. hmm... someone brought it to me

[CWW]

Make sure to also check the condition of the wiring in the ETA unit. It also degrades, and can cause these issues. As long as you're doing the main loom, may as well replace the ETA wires as well. There's a DIY floating around somewhere, or there are shops (at least here in the US) that rebuild them for not too much money.