SEOJustin

I have only had the car a couple of weeks, the other night there was a very heavy rain while I was at work. When I went to get into the car and drive home I noticed the Low Trac light flashed when i stopped, then when i went to take off the Low Trac went off and the ABS INOP light come on. It does this every day now; It will be off when i start the car, but once I get rolling it just does it all over again.

Any ideas? Could this be the wheel sensors or the sensor on the rear-end? I did notice some moisture under the hood by the moroso intake tube; unsure of how it got there?

Injuneer

Go to the "Computer Diagnostics....." forum and download Scan9495. It can scan the EBCM (ABS computer). I can give you a reference to look up the diagnostic codes. You could have moisture shorting one of the wheel speed sensors.

SEOJustin

According to my passenger on the way to work today, it said RF Wheel Speed Sensor Ground/Fault Code 33

I haven't found anything online about this "ABS Code 33" yet in relation to GM cars; guess I will have to just try looking for ground/fault in the harness or go buy a new wheel hub/bearing package from ACD

Injuneer

You can download a 1994 factory manual at this site:

LINK: 4TH GEN SERVICE MANUALS - Firebird Nation

Looking at my copy of the manual:

ABS DTC 33 = Right Front Wheel Speed Sensor Circuit Open or Short to Ground/Battery

Could be a short or an open. Unplug the harness connector for the right front wheel speed sensor (on the back of the wheel hub cartridge) and clean up the contacts. Check for mislocated pins, broken connector lock, etc. Check the wires for damaged insulation. The diagnostic guide recommends that if the problem seems to be related to moist environmental changes, all wheel speed circuitry should be inspected for water intrusion.

SEOJustin

I cannot find anything out of place on the RF wheel sensor, I also tested the sensor with my DMM and got a good ohm reading and also shows voltage while spinning.. It's very difficult to get to the harness on the back side of the front crossmember.

Injuneer

Did you spray it with water as suggested in the ABS DTC 33 chart in the factory manual?

Did you check continuity of the wires to the jumper harness connector and to EBCM?

The output signal is a pulse. Check with the frequency scale of the DMM to see if frequency varies with rotational speed.

GaryDoug

If you are using my app, Scan9495 or a Tech 1/2, you can monitor the wheel speed in real time. I would jack up the corner, remove the wheel, and watch the screen while moving around the cable and spinning the wheel hub at the same time. Might take two people. Watch for zero readings while it is spinning. The readings in this photo are not necessarily correct for normal operation.

SEOJustin

No, I did not spray it with water. I will download that factory manual and read the recommended diagnostic steps. Continuity was good; I do see it varying based on how fast im spinning. I have not checked the jumper harness yes as I still have to trace it back.. Im still digging at it trying to get my abs power brakes back on =/

Gonna try the 94/95 thing today if I can.


*EDIT> Would changing the VSS Diagnostic setting in the computer affect my ABS? I read about the "stall wall" and was told that raising the VSS diagnostic RPM would help with the stall wall issues, I did set it up high.