PeachParts Mercedes-Benz Forum - View Single Post

EricSilver · #37 10-16-2008, 04:36 PM

So far, I have done nothing, since there have been no issues.

However, what I wrote previously about voltage issues is only circumstantial. I now am convinced that my problem is related to the stop light switch.

After my last post, I did some experimenting. The issue has nothing to do with low voltage because, upon starting the car after sitting over another weekend, I turned on all lights, radio, etc. Nothing happened. If it were a voltage issue, as I originally conjectured, then the ASR would have tripped.

As long as I did not touch the brake pedal, the ASR fault was not triggered. If I idled the car for 1 to 10 minutes after startup (depending on temperature and humidity) I could drive away with no ASR issues. If I tapped the brake at any point before then, the ASR fault would appear shortly or immediately thereafter.

Not sure how it works, but the Stop Light Switch is involved in several functions, i.e. cruise control, ABS, ASR, etc., in which the ETA is also involved. So the likelihood of miscommunication is great.

On two or three occasions, on the first drive of the day, I have also heard a short, low buzz when applying the brake, very similar, if not the same, as the buzz you hear when you leave the key in the ignition – or when you blow the fuse that controls the instrument cluster gauges. I have never read any documentation on this, but that buzz might be a faulty stop light switch warning.

We have cold weather returning tomorrow, and I will observe the behavior once more, before going ahead and ordering the replacement switch (as I should have done months ago).