PCM Diagnostics & Tuning - ABS experts...stumped?




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quiksilver9531
04-29-2006, 05:37 PM
Ok first thing first, my car is a 2000 trans am ws6, 6spd without traction control. I had a code for a Valve Relay circuit malfunction C0121, but it ended up being the ABS BATT mini fuse so that code went away but I still have a code for a rear wheel speed sensor, forgot the code number.

Heres where it gets confusing, I had the car hooked up to a scan tool from my work, and watched the wheel speed sensors, when I was going 40mph, the front wheels read 40 and both the rear wheels read like 20mph, I locked up the wheels a few times and the abs does not go on, but for some reason the abs will randomly make my brake pedal hard when I go to stop, I would assume that is probably from the sensors being off.

Now this is what I really don't get, my car doesn't have traction control but I have a wheel speed sensor for both rear wheels, not the single sensor in the differential, I thought only traction control cars had individual sensors. I put my car on the lift and had another mechanic spin the driver side tire while I was watching the scan tool, both rear wheels read 2mph, didn't make sense since the passenger tire was barely spinning, so I unplugged the harness from the wss on the pass side, and spun the tires again, still read 2 mph for both rear sensors, I then switched to the passenger side, pluged it the harness back in and had the other kid hold the driver side tire and I spun the passenger tire, the scan tool read nothing. Pretty much to sum that up only the driver side tire reads for both rear sensors, pass side sensor does nothing. But the rear sensors are still off from the front two. Im guessing maybe a possible short somewhere...Any ideas?? :confused:


2002_Z28_Six_Speed
04-29-2006, 08:49 PM
Anyone own the car before you?

YoMommasTA
04-29-2006, 09:30 PM
could it be someone replaced the rear with a TC rear and fudged the sensor wiring?without TC i'm sure you should only have one sensor at the rear reading the differential speed


quiksilver9531
04-29-2006, 11:29 PM
Yea but I got the car at a dealership so I don't know who it was, yea something real funny is going here, because it is not a traction control car but it most definatly has two rear abs sensors, after I bought this car I realized that not all the warning lamps illuminated when I turned the key, so I took the cluster out and the guy tampered with the circuit board to hide the fact that that the abs inop and brake light were on, must have been a clever little guy haha.

2002_Z28_Six_Speed
04-29-2006, 11:30 PM
Yea but I got the car at a dealership so I don't know who it was, yea something real funny is going here, because it is not a traction control car but it most definatly has two rear abs sensors, after I bought this car I realized that not all the warning lamps illuminated when I turned the key, so I took the cluster out and the guy tampered with the circuit board to hide the fact that that the abs inop and brake light were on, must have been a clever little guy haha.

That is what it looks like but you can still fix the car! It is not ruined. Nothing in my car worked when I got it.

quiksilver9531
04-30-2006, 12:37 AM
Well now I'm just trying to figure out how i have a 4 channel abs without traction control, i dunno I'm not gonna put a lot of money into fixing the abs, if my friend or I can't figure it out, then forget it, its only abs, dont need it