ABS Questions

[alan325i]

Hi

Just picked up a new(er) 325i unfortunatly the ABS light is staying on .

Anyone know where the ABS sensors are on the system and also if its not one of the sensors how easy is it to replace the whole ABS

Thanx

[dazleeds]

hi the sensors are on the hubs on each wheel
and prob only need to be removed and cleaned up as they get lots of crap on em hth

if you do need to replace they are easy to do just unscrew from the hub follow the wire and pull connector apat

[alan325i]

thx, what happens if it aint the sensor and is the main ABS thingy is that easy to replace?

[Brianmoooore]

Need more detail of the symtoms.
Light comes on when you switch on the ignition?
Goes out when you start the engine?
Stays on when you start the engine or comes on again when you start to move?

[alan325i]

i start the engine, light goes out, but as soon as i start moving light comes on and stays on

[Brianmoooore]

This is a sensor problem. Locate the four round white plugs and sockets from the wheel sensors, and unplug them. Two are on the front inner wings, and two are under the back seat cushion.
Measure the resistance of each sensor with a meter, across the two pins.
Each one should read between 900 and 1000 ohms or there abouts.
Chances are you will find one that reads open or short circuit.
When you've found it, check the lead carefully all the way to the wheel sensor. You may find damage that can be repaired. Otherwise you need a new sensor.
If none of the sensors are dud, then it may be dazleed's crap on the sensors and toothed wheels.
They don't always come out quite as easily as dazleeds says either.

[alan325i]

thanx again, will have a go tomorrow

[BigChris]

Just thought id add. i had the same prob and it turned out to be a connection in the ABS relay had gone, so it was a case of soldering iron out etc hope that helps

[Brianmoooore]

Just thought id add. i had the same prob and it turned out to be a connection in the ABS relay had gone, so it was a case of soldering iron out etc hope that helps

You sure your symptoms were exactly the same. Light goes out, but comes back on again when moving?

[dazleeds]

If none of the sensors are dud, then it may be dazleed's crap on the sensors and toothed wheels.
They don't always come out quite as easily as dazleeds says either.


my mistake i should have said that they dnt always come out that easy sorry

reason i suggest cleanin them is in the history for my old 325i once a year the sensors were removed for cleaning as it seems they would show a fault every year whoever owned it before me paid out yearly for the
sensors to have a full clean up at the dealers
this also happened when i did own it so i removed and cleaned them all and that solved the prob

[Brianmoooore]

Gunged up sensors and toothed wheels is a well documented cause of ABS problems, but there is a considerable risk of damaging perfectly good sensors by trying to remove them, so the first check should be the resistance checks in my first post.

[alan325i]

well done that man, was one of the front sensors that was cream crackered, all working now

Thanx for advice