Strange ASR malfunction Light - 97 E420
 

I encountered some very strange problem with my 97 E420 (80K miles) this morning while stuck in a big traffic jam in southern CA. I was in the traffic jam for over 2 hours barely traveled 2 miles within that time because of a big tanker truck accident and the resulting freeway closure. All of a sudden, the little red ASR malfunction lamp came on at the left side of the instrument cluster and the engine immediately lost almost all power. I was lucky enough just able to pull over to the shoulder and stop the engine. At the time when this happened, all other functions seem normall. After waiting another 2 hours for the tow truck, I started the car and the engine ran normal again as if nothing had happend. This time there was no ASR malfunction light and I was able to contine my trip without further problems . My question is why did the ASR malfunction light came on when the rear wheels were barely moving forward and not even slipping? Is my car's ASR system about to fail and what is the typical cost of fixing these problems. Thanks in advance for any tips.

Garry

This could be a stab in the dark, but my mother has a '99 E430, and her ASR light came on and had a similar stalling experience.

I think her problem was due to a charging problem / bad battery.

I went through the search function and learned that it could be as simple as a bad brake light switch which could set-off the ASR malfunction light. Is it difficult to replace the brake light switch?

Garry

Very easy - on a W124
 

it was easy to replace the brake switch on my W124 (E420). Not sure about the W210. On the W124 - it's right above the brake pedal. Takes about 10 minutes. Maybe less.

Troy
1995 E420 77k

Probably not a brakelight switch, as a bad brakelight switch probably won't make the car go into limphome mode. I'd suspect the throttle actator, but you need to get the trouble codes read.

Gilly

Garry,
Did the engine really "lose all power" or did it just take a lot of accelerator pedal movement to produce in increase in RPMs? The latter is what Gilly referred to as "limp home" mode. Most likely that's what happened. You can still drive the car but throttle response is "weird."

Gilly of course is right that to track this down you need to have the codes pulled. I was the one with the bad brake light switch, but the only way it got diagnosed was via the codes. At the time I had that problem, I was getting an ASR and an ABS light, and going into "limp home" mode every time I started the car. Replacing the brake light switch cured that problem.

On the other hand, I still get an ASR malfunction light from time to time -- about once a year -- and everything works great in between, so if your system is at all like the earlier ones, this may never happen again, it may be a very intermittant problem, or it could be a sign of impending failure of the throttle actuator or some other component. The codes will help decide this.

But then again it could very. . . .
 

well be the Elec Throttle Actuator (ETA). I agree with Gilly, since that's how my problem started. Scary thing the first time it happens, isn't it?

You do need to dump the DTCs. Check out my page (click on the 'WWW' icon below), Menu#24.

I believe when it happened, the engine just went into the limp home mode (idling normally but would not rev much with throttle increase). I experiment with a new brake light switch and so far for about a week the problem has not returned. It could still be the throttle actuator problem but I will just have to wait and find out.

Thank for all the advices.

Garry

if it is the brake light switch what method would you use to test it. I dont like to throw parts at a problem, it would be great if I could test the brake light switch first.

I don't have any means to test the old switch. I replaced it because it is only $18 for a new one from the dealer. So far after a few weeks, the car is still running normal (knock on wood!)

Garry