Merc electrical problems??

[Chambo]

My 1996 C class Mercedes has a number of unusual random problems which I assume are electrical issues and my mechanic has never seen it before.

Problem 1.
Basically on purely randon occassions the fan will come on full and cannot be turned off.

Problem 2.
The other random problem is all the following things all occur at once, the speedo stops, crusie control won't work and the 3 brake warning lights in the instrument cluster come on all at once and then the car won't idle properly. Then after doing this for a random amount of time everything goes back to normal and the car runs perfectly.

Both these problems occur purely randomly and of course did not occur in front of the mechanic. My mechanic could not find any problems.

I assume I have electrical or computer problems? Does this car have any inbuilt computers???
Help comments or help would be appreciated??

 

[Chambo]

I am now having an additonal problem, basically the green/red lock / unlock the car lights will flash on and off randomly ie when driving along they will ramdomly flash.

Therefore my car has 3 problems;
1. the fan / heater will turn on randomly;
2. the speed stops and dash brake warning lights come on;
3. the car lock / unlock red&green lights flash randomly.

Does anyone have any ideas that could solve this problem?

 

[grober]

Sounds like you need a GOOD!!!!!! AUTO ELECTRICIAN. I dont think this model has a DATA BUS TYPE WIRING SYSTEM but there were some issues with wiring insulation degrading on some models around this time. I think they were cured by the time of your model though. Detailed visual inspection of wiring particularly in engine compartment required, look for crumbling plastic insulation. Otherwise your symptoms indicate that voltages are getting to places they shouldnt. leakage to earth or to other wires. this could be caused by faulty insulation or perhaps water leaks. does the problem get worse in wet weather?? front windscreen area likely candidate. you can check for current leakage to earth on various circuits by isolating various fuses but you need to know what your doing! this sort of problem can eventually fry your ECU so get it loked at soon. good luck