Comments on: FAQ > ASC or DSC, ABS, Brake lights on. What’s up?

By: BMW ABS AND ASC LIGHT ON | World Car Blog

BMW ABS AND ASC LIGHT ON | World Car Blog — Mon, 24 Oct 2011 08:52:18 +0000

[...] bmw abs and asc light on bmw-planet.com [...]

By: patrick s

patrick s — Wed, 16 Feb 2011 14:05:58 +0000

mostly there are two types of abs(asc, dsc whatever)systems installed in e38 and e39
pre 9.98 and after
pre 9.98 has only hydraulics in engine compartment while after 9.98 has all electronics and hydraulics there.
when pre 9.98 systems control units will not fail at all, after 9.98 control units FILL FAIL WHEN DRIVING WITH ABS LIGHT ON.
when your system will stop working and you have car produced after 9.98 it is essential to remove main connector from abs/dsc unit to protect it. then you can safely drive to car diagnostic and diagnose your problem.
if you have pre 9.98 and having acs only not abs lamp lit then you have to check cable that connects asc control to throttle body (petrol engine). later models will have eml lamp added to system, then its probably electronic throttle body or connecting wires that are failing (petrol engine)
asc or dsc control units have to be coded when changing engine type (petrol-diesel)
dsc control units need to have steering angle sensor and acceleration sensors adjusted

btw. left rear abs sensor will transmit speed signal to speedo

e46 abs will not fail from broken(shorted)abs sensor.
they have other common problems but its another story already
patrick s

By: Takechan

Takechan — Thu, 17 Sep 2009 07:22:50 +0000

Admin,

No, thank you! I managed to solve another electrical problem as well thanks to this great website (BMW WDS).

The driver door didn’t work, or well only my window and side mirror did. I couldn’t control the passengerside window or mirror. The central lock didn’t work either (only on the other doors).

So the door had no connection from the door to the general module, meaning a problem with the P-BUS. I managed to find the pins by looking through BMW WDS, so I could measure the resistance from the wire in the door – yeah it was broken, so I installed a new wire and now everything works again!

By: Admin

Admin — Wed, 16 Sep 2009 20:17:56 +0000

Thanks for sharing your experience with us buddy, much appreciated.

By: Takechan

Takechan — Wed, 16 Sep 2009 09:11:12 +0000

Hi,

I’ve been dealing with a ASC/DSC problem for a long time. My car is a BMW E39 520i from 1996 (December).

I had my car scanned with INPA and it showed a fault on the left front speed sensor. I replaced it, but the problem persisted. I then measured the resistance through the speed sensor as well as the resistance through ASC/DSC unit. No problems.

Now only two things could be wrong. I was 100% sure it was my ASC/DSC unit which was faulty, but getting a new (used) one would be quite expensive (I live in Europe). I instead got a new left wheel bearing and replaced that first. Solved the problem!

The magnetic ring in the bearing had somehow become damaged. So the first sensor I replaced was actually working. It was just destroyed when it was removed, because it had never been removed before.

So, I just wanted to say that remember that it’s also very probable that there might be something wrong with your wheel bearing. So check the resistance/wires also!