Steering angle sensor probs

[benscab]

I have the dreaded abs trifecta and also think it might be related to the sas , I sometimes have to reset the sas every other day and get no response from control unit when I try to diagnose the abs fault.
Any ideas anyone ?
Tia

[Smeeagain]

if you are having to resent the sensor every day then the unit is probably faulty and needs replaced. Can you get a fault read on it?

Smee

[Horizon]

I also think the SAS has to be coded to the car once fitted.

[benscab]

It did once throw up a code for steering angle sensor , could that be the reason for the abs module not responding though ?

[Horizon]

I would have thought the ABS module should respond, even if the SAS was faulty, it's only an input just like a wheel sensor. The fact that it resets shows the module is working. Maybe try a different scanner.

[henrym3]

Have the same sort of problem but only comes on if I'm tight maneuvering, ie back/forward with lots of full lock. Normal parking is fine. Turn off. Key out. Key in. Start always clears lights. Never any fault codes stored. Must try checking for codes while lights are on, before I switch off.

[henrym3]

Ref above post, I got the opportunity today and read the codes before switching off. Only fault showing was that bloody front left wheel sensor with intermittent fault. No SAS faults. That sensor has had a cheapo sensor and then a more expensive named part. Probably in hindsight there was nothing wrong with the original. Anyone like to steer me as to why this is persistant.

[Dave ett]

I had a pig of an ABS fault on my E39, and had to resort to buying myself a portable oscilloscope so I could read the output of the sensors whilst driving. Does that sound a bit scary for your skills?

[benscab]

In a word ........Yes !!

[Dave ett]

)

It is a little bit involved, but wasn't technically that difficult.

A simple overview was:

I got a copy of the ABS wiring to the controller.
made up some skinny wires (unfolded paper-clip I think) to poke into the ABS module plug so I could read the signals whilst it was plugged in.
Put the probe of the 'scope onto a good wheel to get a 'normal' reading while I drove along.
Stopped and switched the probe to the suspect wheel while I drove along.

It was really obvious that a good output is a nice square shape on the screen, while the bad one was all over the place.

Turned out to be the new hub I'd fitted (hub has the bumps on it the ABS sensor reads).  I'd just replaced it, and after a bit of trial and error found the ECP one didn't work, but a GSF one did.  Weird as they looked identical.