Rear ABS

[andrebsd]

Hello,

I got a problem with the rear abs on my (recently aquired) 1989 525i; when stoping quickly both rear wheels will lock, the front abs works fine. The dashboard light also doesn't stay on/flash as if there were a problem. I searched the forum and came across someone mentioning a DME thing (no clue as to what DME stands for) not acting fast enough?

For the rest, it's wonderful to drive. Though I would like full ABS to work :)

Edit: fixed a stupid typo.

[azale]

(no clue as to what DME stands for)
The DME is the BMW's main computer; I think it stands for something in German. It is located under a plastic cover (probably secured with 4 screws or bolts) in front of your passenger seat in the engine compartment. At least that's where mine is.

I don't know much about ABS but my dad's van has a sensor that reads teeth on the inside of his rotors (it's just like the crankshaft position sensor I just replaced). If the teeth stop moving abruptly, ABS kicks in. If your car has 4 wheel ABS it has similar sensors. That may be a good place to start. Check to see if your rotor is missing teeth or if it is very dirty. Then check if the sensors are dirty or broken. The computer should tell you if there is something wrong but it wouldn't be the first time a computer was wrong.

The connectors for the rear pulse sensors are under your back seat.

Where/why have you been locking up your tires to notice that they weren't working?

[DanDombrowski]

The previous owner probably disabled the rear ABS to allow him to drift better.

I'm sorry, that doesn't really answer your question, and I'm not making fun of you, just a little joke the rest of the board will appreciate.

[azale]

The previous owner probably disabled the rear ABS to allow him to drift better.

lol. Hey, when you've got talent . . . :)

[dacoyote]

The previous owner probably disabled the rear ABS to allow him to drift better. .....

LMAO....

-Charles

[uscharalph]

The previous owner probably disabled the rear ABS to allow him to drift better.

I'm sorry, that doesn't really answer your question, and I'm not making fun of you, just a little joke the rest of the board will appreciate.
Very Funny, Dan! LOL!!!

[Kalevera]

The car's ABS system is too early for most of the modern diagnostic tools. Even if you can find a dealer that still has the tool, if there are no fault codes (and thereby no ABS idiot light active on the dash), there's not much that can be done in the way of computer diagnosis, regardless.

If it's a US car, it has a 4 channel system. When was the last time the brakes were bled? It needs to be done yearly. Do that, then start suspecting the ABS pump.

best, whit

[andrebsd]

Re: azale & lowell
-----
I tried it here on an empty road, got the car to about 25 and slamed the brake pedal down... It's just so I know what to expect if I do have to brake quickly and for some reason I was a bit curious as if it did work.

I may have to bleed the brakes again, as the entire engine was out recently to replace a burned piston. (Previous owner overheated it, but for some reason replaced the head, but not the first piston that was burned... So the engine knocked)

I'll check the connectors and stuff too for dirt; at least the front doesn't lock up... that would worry me a bit more than the rear not working.... And hey if nothing else, i'll just take DanDombrowski's advice and go drifting, lol.

[Interceptor]

The DME is the BMW's main computer; I think it stands for something in German.
DME = Digital Motor Electronics
DDE = Digital Diesel Electronics