hey guys my abs and brake light have came on. i have a 2002 1500 QC 4x4 with a 5.9 magnum. it also has rear abs. so the light came on the other day and my first thought was the sensor in the rear axle. well i replaced it and the light is still on. i also check the abs unit next the battery to see if there was any moisture on the plug, and it was dry. so i went down to the dealership to get a diagnostic done. well that was a waist of $100. So i still have the same issue on the truck. i really need yalls help, can some one please tell me what it could be or how to fix this. Thanks in advance

 

please guys i really needs yalls help

 

I just had the same thing happen, started the truck up on the first really cold morning of fall (for TX anyway) and I got the ABS and Brake light on now.

What did the dealer tell you after the diagnostic was run?

 

For the '03, looked at the wiring diagram in the service manual and first thing to check is fuses 6 (which is battery) and 35 (which is from the ignition switch). This may be different than your '02.

Do you have all wheel ABS or rear wheel only? Mine has all wheel ABS, so it has a sensor at the rear axle and one in each front hub.

I would assume that the sensors themselves read as close to a short if it is a magnetic pick-up. Anyone know if that is true?

 

Fuses are ok and 12 VDC is present at #6 all the time and on #35 when the ign sw is on. well so much for the easy part...

 

mine has rear wheel abs...ill have to check the fuses when i get my truck back.

 

At the Controller Antilock Brake (CAB), connectors C1 & C2 have the connections for the speed sensors:

Right front speed sensor
C2 pins 3 & 4 reads approx 1 Kohm
-- which means this speed sensor circuit is not just a coil,
-- there is probably a low-pass filter for noise suppression
-- or spike protection circuits at the sensor.

Left front speed sensor
C2 pins 1 & 2 reads open, more than 2 Mohm

Rear speed sensor
C1 pin 1 & 8 reads approx 1.6 Kohm

JDG, you may not have the C2 connector if you have rear wheel ABS only.

After seeing the open on the left speed sensor I took off the wheel on the left side to look and everything is still connected and looks normal. There is another connector for the speed sensor wires on the inner fender wall on the engine side of the wall. I checked that connector and the open is still down toward the sensor. That hub is making mechanical noise anyway, so I will swap it out.

You can find these connector pin-outs in the service manuals. I think Weed has the '02 manual, not sure...

Good hunting,
BR

 

Almost all abs problems are wheel end. Did the dealer specify which wheel sensor is bad? Chances are
the sensor side is fine. The wheel hub has a exciter ring on it. Check to see if the exciter is rusted up.

 

yes i only have rear abs. so there are no sensors in the front. the dealer told me that the main sensor in the pumpkin is bad, so i replaced 3 times. so they said i need to clean out my axle and put new gear oil and it will go away. when i changed the sensor there were no metal shaving or chunks on the sensor. so now that i have changed it out 3 times im still having the same problem. i also checked the fuses under the hood and they are good also. so now i have no idea what to do. but i am hearing a click noise from the rear

 

Was driving back from Atlanta last weekend in the wives Mini and a car in the next lane over hit a piece of a tire and it flew over to my lane and I hit it.

Right after that I lost my speedo and the ABS light came on. Good thing I have a smart phone with GPS so I could still clock my speed for the rest of the way home.

Anyway, got it home and lifted up and on the back pass side tire where the ABS sensor was, you could clearly see one of the wires was damaged and broken in two. A new sensor was $40. Not too bad but a few minutes with the soldering gun and a piece of heat shrink and it was good as new and everything worked as it should afterwards.