'99 e39 540it: sudden onset of strange problem

[tim]

So the wife comes home and says there's a light on in the car. It's the DSC deactivation warning light. Pressing the DSC button will not get it to go off. Also, the ABS, Brake, and "service engine soon" lights are on with it! Yikes. Please tell me this is a relay or something. The car has no physical symptoms and runs fine. Nothing like a pothole or bump or anything to report (although the wife always says that- and later she'll say something like "oh yeah, well.. I hit a deer on the way home, do think that could be it hon?"

Anyway- help!

[tim]

I'm thinking wheel sensor, relay, or (gasp) abs controller. Ne1?

[632 Regal]

bump

[Brandon J]

Hmm, at first glance looking at the commonalities it sounds like a bad ABS wheel sensor. No worries as they are simply a magnetic pick-up so not an arm and a leg. The fault code should say what it is. The car uses the ABS wheel sensor for the traction control too. Newer cars also use this sensor to determine if a tire is low on air. They all take measurements of how fast each wheel is spinning relative to each other and makes braking adjustments for braking (ABS and traction). On newer equipped cars, the low tire pressure light (or message) will appear when the ABS wheel sensor senses one or more wheels rolling faster for a given speed relative to the other wheels....b/c of the less air, the tire will have a smaller rolling diameter and thus roll faster.

[Bill R.]

comes back again right away... sometimes its a random fault and won't reappear again for a long time.. other times if its a wheel sensor the most common on the 99 is the right rear wheel sensor so that would be the one i would check first. If that isn't it check the seating of the harness on the abs controller module . And if that doesn't help its typically a bad abs/dsc control module.... One other thing to check first is the brake light switch, if its bad it will trigger the same fault.

So the wife comes home and says there's a light on in the car. It's the DSC deactivation warning light. Pressing the DSC button will not get it to go off. Also, the ABS, Brake, and "service engine soon" lights are on with it! Yikes. Please tell me this is a relay or something. The car has no physical symptoms and runs fine. Nothing like a pothole or bump or anything to report (although the wife always says that- and later she'll say something like "oh yeah, well.. I hit a deer on the way home, do think that could be it hon?"

Anyway- help!

[tim]

Thanks Bill,

I'll check it out. But what do you mean by "brake light switch"? You mean the light itself?

Thx,

tim

[Bill R.]

Also , places like autozone will have a generic obdII code reader that you can read and clear the codes with.. they will do it or i think they have them as loaner tools also..

Thanks Bill,

I'll check it out. But what do you mean by "brake light switch"? You mean the light itself?

Thx,

tim