Apostle Proteus

HI all - bought a 1989 944 NA 2.7L recently and have been working through problems that the PO didn't address.

Tried tackling the dreaded always on Anti Lock brake and "!" lights.

What I did so far
1. removed the ABS Module connector under the passenger seat.
2, tested resistance on all four wheel speed sensors from that connector - all of them at 1K
3. Tested all ground connections pins 10/20/34
4. connector a voltmeter on pins 1 / 34 - only read 3.9mv with the ignition on
5. pulled G20 relay and jumpered pins 30/87 - meter read 320 mv

Since I hear the relay click, I think its probably ok and I'm just testing the wrong pin.

Does anyone know which pin I should test to confirm power is getting to the ABS unit?

Bonus question - found some exposed wiring that goes through the top firewall to the left of the blower assembly. Anyone know what that's for?

Much thanks..

four0four

Try cleaning out the ABS speed sensors themselves - they get clogged up with, well, basically anything magnetic that gets in the area. For each corner, yank the wheel and follow the ABS harness to the connector. Should take a 6?mm allen key. Gently remove it, blow it out with air or something, and put everything back.

This isn't something you can catch with a DC resistance test - that only serves to indicate the sensors are wired in and not physically broken. The computer measures the reactive component of the sensors' impedance, which won't be visible on your everyday multimeter. Good luck!

Another thing to narrow it down might be this: Does the (!) light come on at startup, or does it come on when you move the car?

Fair bit of wiring back there. Got pictures?

Apostle Proteus

I started tracing the wiring using this (http://www.bakody.com/Rennlist/944ABSdiag.jpg), only to discover that no power was getting to relay pin30 - blown fuse #26. Which I swear I tested before. So replaced the fuse with the relay(G20) out and was fine until I plugged it in - hear a click and immediately blew.

According to the circuit diagram on the relay, I should be seeing open circuit on the connection from 30 (+) to 31(-) but showing short in both directions. Diode test shows zero voltage as well. Going to see if I can replace the diode as the relay otherwise works.

Will post further findings.

Apostle Proteus

I started tracing the wiring using this (http://www.bakody.com/Rennlist/944ABSdiag.jpg), only to discover that no power was getting to relay pin30 - blown fuse #26. Which I swear I tested before. So replaced the fuse with the relay(G20) out and was fine until I plugged it in - hear a click and immediately blew.

According to the circuit diagram on the relay, I should be seeing open circuit on the connection from 30 (+) to 31(-) but showing short in both directions. Diode test shows zero voltage as well. Going to see if I can replace the diode as the relay otherwise works.

Will post further findings.

Apostle Proteus

Ok opened up the abs relay (92861512401) for additional testing and to see if fixable ( see below ). Pretty sure the zener diode ( black ) piece is toast so ordered a new relay. Could probably replace it, but not worth the effort to do so.

While this is in transit was looking to verify the rest of the circuit. Need help to find the 4 pin plug near CEB (Fuse Box) - labelled "I" in the wiring diagram.

Apostle Proteus

Update: didn't bother with the rest of the trace. Jumped 30/87 with a working fuse in place and heard a click. After starting the car the lights went out finally.

New relay is all that was needed. Looking forward to getting her on the road - she needs to run.