'91 420sel ASR/ABS lights on, no cruise control
 

I had a valve/timing chain/head gasket job done on my '91 420sel last week. Everything worked fine until yesterday when the ASR light came on and stayed on. Then the ABS light came on (it later went out). Also noticed my cruise control was out.

I saw this combination of failures listed on one other post while researching the problem, but there was not much in the way of resolution. Most of the threads about ASR problems are for newer MBs and many talk about the vehicle going into "limp home" mode. Mine is not doing this...plenty of power left.

Some of the potential fixes offered on other threads were the brake lamp switch or a bad wiring harness. Voltage problems are also mentioned. (I did have the voltage regulator replaced on the alternator during the engine overhaul.)

I have not taken the car to a dealer to check codes and am not sure with this year and model what electronic diagnostic capabilties are available.

Would anyone with experience with this problem on this model please give me some specific advice as to what to look for?

Thank you.

I'd be inclined to check the linkage for proper adjustment. Is the idle correct? On the 117's I've run into with ASR, power or control unit failure is normally accompanied with high idle. I've seen damn few of these so odds are I wont be much help.


Joe

Sounds like you saw my post from March, where the brake lamp switch went out and which produced the same symptoms.

If you look at the schematic on the CD, you'll see that there are MANY inputs into the engine control unit and the electronic throttle unit, any one of which can go bad and produce similar symptoms. The most cost-effective way to track down the problem is to pull the codes. Even if you go to the dealer and pay them for an hour of diagnostic time, you'll come out ahead.