Ok, so after havign the car scanned and seeing that the abs light was coming on because either "the sensor was bad or the wire was grounded or shorted" on my rear end; i have just replaced the rear sensor with no luck. The light still comes on after about 20 ft of driving. Does this mean that somehow magically the wire just grounded itself one day? How can it still be reading the rear wheels at 0 mph with the new sensor? Any ideas what it could be?
Thanks
Bill

 

I wish I had a good explanation for my problems, too.
My abs light comes on every time I step on it. It's wierd. And the manuals I have don't go into too much depth about it...

Anyone familiar with ABS systems?

 

Have your charging system checked out. Sounds weird but many many times I have seen the ABS light come on when the alternator is going south.

 

Well the light has been doign this for almost a full year. I think if the alternator was going bad it woudl be dead by now. Also because it wont come on unless the cars in motion, i would think it would have to be somethign with the sensor. Maybe the wiring, if nobody has any ideas, ill be calling the dealership on monday, swallowing my *****, and paying them.
Bill

 

Try taking a look at this thread

http://web.camaross.com/forums/showt...threadid=97836

 

Thanks for the help, but again, the light does not stay on, so i dont think i could possibly be any problem with a light or any other problem. It has to do with the rear sensor because you can do whatever you want with the car sitting stilll, jacked up driving, or what not, but the light wont come on until driving with all 4 wheels spinning.
Thanks
Bill

 

are your tire's the same size from front to bacK?

 

is it your VSS?

or possibly you vehicles front speed sensors... like on the front wheels!!!!

 

Get a shop manual and follow the troubleshooting sequence.

Rich Krause

 

Have you checked the wiring all the way to the PCM? Don't forget the rear ABS sensor has to go through the connector behind the seat(near the tank vent) all the way through the cabin under the carpet, door sill and kick panel across the IP through the firewall to the PCM. The first thing to do is ohm out the wiring from the sensor to the PCM and if that's ok, try putting the signal directly to the pins of the PCM and see if you get sensor output like we did the other week with the real time data scanner.

 

Yes the tires are the same size, and thanks slow poke, i was just about to ask if anybody knew the route of the wire so that i could track it down and check for grounding. It shouldn't be the front sensors since scanning it said that the rear wheels were at 0 mph the whole time driving. Ill try to trace the wire, but its hard to work in 90 degree heat with a completely sunburned body
Thanks
Bill

 

Well instead of tracing the whole wire, i just realized an easier way to see if theres a problem. We measued the wire going to the sensor bringing in about 3.5 volts. If somebody knows the correct amount, or could measure theirs to see what the voltage should be, i can determine if theres a problem with that wire or not. I have no idea if it should be 12 volts going to that sensor and meaning theres a problem, or if 3.5 volts is all it takes. Anybody wanna test theirs?
Thanks
Bill

 

Well the fun part starts. Under the dash above the dead pedal is the brake control module. You have to take the screw out and pull that down. It's a metal box with 2 connectors on it. Pull off the Grey connector that has 24 pins on it.

Looking at the pin end of the connector on the harness (not the BCM connector) with the latch up. Top row, 3rd pin over from the left should be a black wire. Remember this as A3. The other wire for the sensor is the red wire on the second row, 2nd pin from the left. Remember this as B2. Measure the resistance between A3 and B2 (red and black wire). The resistance should be between 908ohms and 1292ohms. Make sure you have the 3rd pin on the top row and second pin on the bottom row. This is where I believe you will find the trouble.

While you're there, check each pin to ground and with power on, check each wire to see if it has 12 volts on it. Now assuming you have a break in the wire, you will need to ohm from the BCM connector to the sensor harness near the fuel tank vent. There is one more connector between the BCM and the sensor connector in the rear. It is C200 and it's located under the driver side dash between the kick panel and the column. It's the huge connector with 3 connectors plugged into it. This will be the best point to search for the open wire.

Pull the skinny black (17pin) connector away from the black 48 pin mating connector. Looking at the pin side of the connectors not the wire side, the 2 pins you are concerned with are the 3rd(black wire) and 4th(red wire) from the left end of the 17 pin connector. This connector goes to the BCM connector you unhooked earlier (remember the A3 and B2). Ohming from the 24 pin connector of the BCM to this 17 pin connector will tell you if the break is there.

Now you want to check from the big black 48 pin connector to the sensor plug under the car by the tank where you plugged the sensor in when you replaced it. On the 48 pin connector, 3rd pin and 4th pin from the left end, be sure they are red and black wires next to each other. These you will ohm directly to the sensor plug at the rear by the fuel tank. You will need help and a roll of wire to check this cable since it is too long for the meter leads to reach each end of the harness. If you need help with this call me and I'll help you.

Dave

 

Hey dave, just spent awhile outside sweatin my *** off in this 90 degree heat. We checked the red and black wires, A3 and B2, and the resistance was good, and then we checked the wires for voltage and grounding. A3 and B2 showed neither, and i believe pins 6 7 9 11 and 24(bottom row last pin) all showed 12 volts. The very first pin showed only 5 volts. We could not find this pin in my chilton ( i think im going to be buying the chevrolet schematic book for future reference). So we do not know if that pin is supposed to have only 5 volts, or if that is the culprit sending little voltage to my rear sensor. We are starting to believe that the module itself went bad, since everything else seems good. Tomorrow we are going to lift the car and tap into 12 volts and send that to the rear sensor via our own wires, and see if that works. We will also be ohming out the wire from the rear sensor to the front connector by the bcm to make sure there is little resistance in that wire. Hopefully tomorrow we can determine what is the problem, possible the module itself. Thanks dave
Bill

 

Don't overlook the simple. A plug wire that is to close to an abs line will cause those symptoms.