A different ASR problem on '92 500E
 

Hi,
It starts with a sound like a air pump was pumping, after 2 to 3 mins later the ASR MIL light came on and the air pump pumping sound stopped. After the ASR MIL light came on, except the ASR stopped working and the throttle got a very little bit heavier but everything else were still functioning normally. At least I felt they were. Usually, my car did not go to limp mode except once and cruise control was working too.

It always happens when the engine is warm. It can be during the car is moving or right after started it again after sit for a while (15 mins to 4 hours). It does not happen when I drive it first time in the morning or after it has sit for a long time (6 hours or more). It did not happen when ambient Temp is above 50F and get worse when ambient temp get colder. It got into limp mode once when ambient temp is 0 F, but I still can drive it at 3 gear.

After dealer read the code, they said I needed to replace
Stop light switch
Brake Switch
ASR pressure Switch
Gas actuator
ASR control

Are there any other small things that my dealer can check before I replace the big items?

If I keep driving my car with ASR MIL light on, will I cause other damage to my car, for example Brake system, or engine?

Plesae help and Thanks in advance.

Best Regards
Jim

I hope you didn't pay much for that analysis. It sure don't take much work to just list all the parts that the codes suggest. Real diagnostics would figure which is the problem. (my guess would be what they called the "gas actuator" otherwise berated as the infamous "Throttle actuator").

I never accept multiple answers for intermittant problems and hate coincidenses.

The brake lamp switch is a good starting place & not expensive at all.
Of course the most likely problem is the throttle actuator.