ASR lite and limp home mode

[Duffman]

Have ASR problems on my 94 sl600. I took it to a local repair shop where they replaced the neutral safety switch and accelerator cable switch[?]. Since this failed to correct the problem, the local repair shop thot it may be the left actuator and would cost ~ $2700. The local shop said I would have to pay for it even if it still didn't work.

I then chose to go to the MB dealer because if the new part didn't correct the problem they will put back the old one with out charge.

After diagnoses the dealer felt it was the main CPU. It ran ok 50 miles then went back into Limp Mode! So back to shop it went and they tried replacing both right and left actuators..still no help.. Next MB suggested it may be the wiring harness which is not avaliable without remake [part#1295407510]

My babe has been in shop 2 months and now they sent me home to wait status on wiring harness.

One odd thing was my cd player, trunk brake lite and steering column switch went haywire just prior to the problem [rearview mirror turns left when steering column switch is used] That makes me wonder if it is wiring harness.

Can there be any connection..THANK anyone with help!

Duffman

[LeaUK]

I struggled to make sense of your post to be honest, perhaps too much texting or too much fine red wine has played havoc with your typing skills? However, after spending some considerable time diagnosing my ASR problem I'm happy to report it's definitely cured, so maybe I can help you too?

The ASR system isn't as complicated as most think - I've unfortunately heard that even some dealers just end up 'swapping out' bits in an endless loop of trying to resolve ASR issues, but in my experience (admittedly through fixing only my car and much circuit analysis) there are several obvious causes of ASR lights which should be addressed first.

Firstly try and isolate the exact cause - accelerator pedal quickly released or at a specific point maybe? Get the car to reproduce the problem repeatedly and make a note of how.

Does the ASR illuminate continuously or just intermittently? Is it lit more frequently during cold weather or hot weather, or something else?

Get as much information together like this as you can to assist your dealer in locating the fault.


Now for my specific tips:

1. Check the accelerator bowden able and linkage mechanism is correctly setup and operating within specification. MB has a procedure for doing this - if it's out of spec you will get ASR lights.

2. Check the accelerator idle switch is operating when it should be. Unfortunately this requires advanced diagnostic gear to read when the switch is active.

3. Get MB to read any fault codes stored in the ASR module.

4. With the ignition on and from within the bonnet (hood) area, remove the air filter so that the throttle valve is visible and move the accelerator regulating linkage (imitating depressing the accelerator pedal) and watch the valve plate move in sync. Does it open/close linearly with linkage movement?

I very much doubt it's the accelerator module - more likely the linkage mechanism, idle switch or Electronic accelerator actuator (that's the unit the throttle valve is housed within.

Also, why not have a search in this forum for similar ASR related problems - there are several previous posts. Also read Jim's fine ASR problem page for fuller understanding of what your up against.


Lea

[Duffman]

Sorry And Thanks!

[Duffman]

Sorry for the confusion. I'm definitly not a typist, it was late and I was frustrated. My ASR lite stays on any weather and always in limp mode.

Thank you for input! I have been checking posts, I will check as per your suggestion. Please keep me posted if you come up with any more!

Duffman

[JimF]

your post and I've found it, no thanks to you. In the future, it's 'nice' to include the link where one might find your post.

Please read very carefully all of the steps in Menu#24 on my page and follow that methodology. . . . . .

First dump DTCs from the ECUs. Without that, you hitting blind. Then post them as we will go to the next step.

From your first post (rearview mirror, etc) might well point to the wiring harness.