E36 ABS sensors on E30 325i ABS possible?

[jaistanley]

Hi guys:

I am fitting the rear swing-arms from an M Coupe/Roadster to my 325i and want to retain the ABS.

After searching a bit and looking at Jordan's posts on r3vlimited I have ascertained that the ABS rings are compatible with the E30 ABS system. The only problem being that the E30 ABS sensors are quite a bit longer than the E36(MCoupe) ones fitted to the arms. This means I have 2 options:

Fit crush washers to space the E30 ABS sensor out (like Jordan has) or;
Fit E30 plug to E36 sensor and use that with no other mods.

My question is: Will the E30 ABS computer work with the E36 sensor? Are they the same resistance etc as the E30 ones?

This question is relevant to anyone fitting Compact/Z3/MZRoadster/MCoupe or E36 suspension to their E30 as well I guess..

Many thanks.

Jai

[Brianmoooore]

The resistance of the sensors shouldn't have any relavent effect I think. The sensors are just frequency generators, and since their voltage output will rise with speed, i would think that the first thing that happens to the signal in the ECU is that it is clipped into a square wave.
As long as the E30 and E36 toothed wheels have a similar number of teeth between front and back, then I would expect it to work.

[jaistanley]

Nice one.

The reason I mention resistance or impedance is that the ECU does a little check at startup (turning the light out) and I wondered what else it could look at??

Jai

[Brianmoooore]

ECU checks on the sensors only when the car moves. That's why, with a sensor fault, the ABS light goes out as normal when you start the engine, but comes back on again when you move.

[jaistanley]

OK.. The light comes on all the time at the moment in the 325, comes on with the ignition and doesn't go out. What could be causing this?

Many thanks.

Jai

[Brianmoooore]

Been discussing this in another current thread.
Short answer is, I don't know, as I've only had this fault once, and it went away, for most of the time, on its own.
It's supposed to be a faulty relay, but a) I opened up and carefully checked both of them and couldn't find anything wrong, and b) I swapped them for some from another car, and the light has put in a brief appearance since.
If the fault became a bit more solid, then I could find it.
The light can be turned on either by the 6 pin relay or the ECU, so it might help to find out which.
The light comes on if the 6 pin relay is not energised.

[jaistanley]

What do they do when an ABS sensor is un-plugged? I ask because the light was reputed to come on after the last owner had some rear disks fitted...Perhaps I need to go round and unplug and replug all the connectors.

Jai

[buster]

This is the reason i have avoided using the e36 stuff to convert to 5 stud,becasue of the abs.
I'll be watching this thread as i would like to know if it can be done or not myself.
good luck


cheers
andy

[jaistanley]

I've not done the swap yet..

Thought it more sensible to get it working in all E30 guise first, then I know the system is good and if I get any problems after swap, which parts are at fault!

I have all M3 running gear on the 318is (which doesn't have ABS) but am going to MCoupé rears primarily for the massive brakes and stronger bearings/driveshafts/swingarms.

Any more input on the light constantly on thing??

Many thanks,

Jai