R129 - Serious electrical problem… grounded until fixed!

[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.

[suginami]

Is this 129 a six or an 8 cylinder?

Only M104s have OVP's. M119 V8s and the later M112 or M113 V8's do not.

[Rud]

Poul its the 119... the probem is, that Im not sure what I'm looking for. I have located a connector with 3 legs, an long kind of pipe, could be a connector as well, around a wire, and then some other connectors which are mounted on a rail. But I can't identify any relays.

Maybe you're right, the 119 don't have the OVP relay and fuse... tomorow, I'll let the Idy look at it, at least make the reset and see if that itself will fix the problem.

Thanx for your reply

Rud

[LeaUK]

You may find this interesting?

http://www.peachparts.com/shopforum/showthread.php?t=139262&highlight=ignition

[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

[tecqboy]

If only the asr and abs light are on, then it is not likely to be a capacitor / voltage regulator problem of the VDO. When the capacitor fails, all the lamps come on. Have you considered problems with the tach pulse from the ABS sensors? Have you searched threads on ETA ( electronic throttle accuator )? Trouble in the ETA can cause these lamps to come on. A non functioning cruise control might be a clue which ties all these problems together, as it also needs wheel speed information. Water in the ABS sensor after rain? ( may have a crack in the case ). Also check the abs sensor plugs ( connectors ) where they meet behind the wheels.