Six momths and 5K miles ago, I suffered a failure of the elctronic throttle actuator in my 95 E320. The new actuator was over $1K, but did cure the problem......or so it would seem. Since replacing the actuator, the car has been flawless, until this last weekend. On the freeway, with the car on cruise control, as we crossed a bridge (+5 degrees F outside temp), the ASR malfunction light came on and the car dropped into the "limp home" mode. We pulled off the freeway and shut the car off. On a restart, the system cleared itself and the car has operated fine ever since.

When I discussed the above with my technician, he believed that the system had operated properly. He believes that there may have been ice on the bridge due to the cold weather, and that when the car began to break traction, the ASR system kicked in and put the car into limp home mode. I'm not certain he is correct. In the past, when wheel speeds differed (one to another), I would get the yellow traction lite to flash in the center of the instrument cluster, but the car never dropped down into limp home.

Since I have spent three visits to my tech's shop and over $1500 on ASR related issues, I'm beginning to wonder if these issues can be sorted out at all! My greater concern is that until I know the problem is fixed, I have no confidence that I can take the car on any sort of trip.

Your comments and suggestions would be appreciated.

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Ernie Rossi

1989 Porsche Carrera Targa
1995 E320 Special Edition
2000 Lexus RX300
1988 190E 2.3

I'm planning on disabling mine someday - just never get around to it. Seems to me there has to be a way to just disable it, take the warning light out, and forget about it. I'm not talking about a disable (on/off) switch, I'm talking about getting rid of it for good. I'd be willing to give up ABS too if that's what it took. Of course I live in Phoenix where they are both worthless - produce nothing but warning lights. Searches here have lots on the subject, especially the on/off switch, but nothing very clear and on point.

If you're trying to salvage yours one thing you should do is clean your wheel speed sensors. It may not help (but it may) but it's easy to do and no parts required. Take each front wheel off, turn the wheel, you will see two allen bolts, remove them, pull out the wheel speed sensor and clean with solvent, reverse process. It looks like a battery post, it's magnetized, and it picks up all kinds of metal debris from the brakes. Mine were filthy. Having it clean will at least make you feel better and eliminate one possible source of the problem.

. . you'll find a clever implementation of an ASR defeat switch. I really don't think you can remove it since the functions are shared with ABS module. Certainly you wouldn't think of removing your ABS?

Also Performance Products sells a ASR defeat but it's not as good as the one described here.

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Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

Ernie,
Your tech is just plain wrong. It is never normal for the ASR system to go into "limp home" mode. You, on the other hand, are correct -- if the system encounters a spinning wheel, the yellow light (not the red ASR fault light) will go on until you regain traction.

There are many things which cause ASR faults/limp home. You've already replaced the most expensive part in the system. Your current problem could be something as simple as mismatched tires or a worn out stop light switch on the brake pedal (been there, done that). A good independent with the proper diagnostic equipment, or any dealer, can pull the codes for you. Chances are that the diagnostic charge will be more than the part you end up replacing!

Don't give up just yet. It's actually a pretty darn good system, all things considered, once you understand it.

__________________
Steve
'93 400E

Also make sure that your engine wire harness insulation is not degrading.

Something else... using cruise control when there is ANY chance of slippery conditions, is an accident waiting to happen.

__________________
Steve

1992 300CE Sportline Sophie
1990 300E Emma - in the family
1979 240D Josephine - sold, but not forgotten
2004 Pacifica AWD

http://web.mac.com/dakota/Mercedes/Home.html

I don't want a defeat "switch" - I just want to permanently and forever disable it. I wouldn't recommend this for everybody but in Phoenix its worthless and a nuissance. And yes I would give up ABS to get there. I'm a conservative driver and in Phoenix could drive a hundred years and never use either one of them. I have no clear recollection of ever having turned on my windshield wipers.