1996 4x4 302 AT. Weird problem. All started one day after sitting a month, abs acted up on 50 miles total trip. OD light flashing, trans shifts fine. No abs light check engine p500. Swapped VSS to to rule that out. After that, same issues plus clicking from front drivers wheel area and also now Speedo jumping above 35 mph. Wiring from VSS to PSOM checks good. Disconnected abs module from behind glove box and it still activates every time I brake. Although the Speedo jumps ways less now. Any suggestions where to look next would be greatly appreciated.

 

Nobody have anything to add or any direction to take? Thinking this weekend opening rear to look at tone ring. After that I guess I need to find a PSOM.

 

I don’t see how the clicking from the front would be related unless you have 4 wheel ABS.

Since the sensor didn’t solve the problem, it sounds like you might have a problem in the wiring harness or in the cluster. Hopefully one of the guys with the test procedures will see your thread to help out.

 

Don’t believe front clicking is related. Just maybe hearing it now because I’m listening for anything and everything that it could be. Clicking may also be coming from left rear area. Sounds more like a relay as abs is activating. Will probably get a signal generator to mimic tone ring to rule it out. Not really looking forward to replacing that.

 

Update. Opened rear for inspection. Fluid was light chocolate milk color. Gears fine. Tone ring looks fine. Put original VSS back in. Still locking up ABS with braking, even when I pulled ABS fuse 15. Speedo seems fine. P500 code still and OD light flashing. Can hear clicking at lower speeds while rolling, coming from rear wheel with no brake applied.

 

Light chocolate milk color isn’t good. Has the truck been through some water?

 

Disconnect the RABS control module. It has been known to drag down the VSS signal before it can get to the PSOM. Pulling a fuse is not enough to isolate that module from the VSS circuit.

 

Hasn’t been through water since I’ve owned it almost 2 years. Disconnected ABS module behind glove box already. No change to braking situation

 

Sorry, I missed that.


Pull the rear drums to see what everything looks like.

Your P0500 code and flashing OD light could be a bad PSOM. You can check the VSS signal input to the PSOM at the RABS test connector. If the input is good, focus on the PSOM.

 

Is the RABS check with obd2 same as obd1? Will it show anything if ABS light is not lit?

 

The RABS system is standalone therefore OBD-I versus OBD-II powertrain control is irrelevant.

There is no way to pull RABS codes with an OBD-I or OBD-II code reader on this vintage truck.