For two years now my ABS light and brake light come on together. I have poked around other sites to try to find a probable cause and most seem to have that issue but also have the abs engauge when truck is under 5 mph. i have never felt this happen. i know when the lights are on, i do not AB's. i can slide the tires in the snow. Any idea what this could be. One guy here at work said that he had an issue similar to this and it was a wire harness somewhere. he had it fixed in the shop and dont know what they did. Any help would be appriciated.

 

Few things it could be. Either you have a bad ABS sensor or a bad ground wire. The ground wire for the ABS is located in front of the stock air box. You have to remove the airbox to find the ground wire, or if you have an intake you should see the two ground wires. One of the two wires is to you abs. Just check which wire leads back to the ABS module. Once you located the ground wire, remove it and find a new spot to ground it too. If that doesn't clear the abs light, then changes are you have a bad sensor. I had this exact issue, and when I replaced my front hub bearings, the abs light went away. FYI the new hub bearings come with brand new abs sensors.

Oh yea I forgot another thing, get the code read and see what it comes up with. It should give you a chassis code. PM me or hit me up on AIM if you have any questions.

 

As nj4x4blaze said, you really should check the codes. Problem is that a GM Tech2 or equivalent scanner will be needed to read the ABS sensor.

 

If you have a hypertech controller it can check those codes as well.

 

also test the brake light switch at the pedal, i have found in many gm vehicles that these fail, causeing the brake light to come on, and abs light.. should be a positive trigger, tap into the wire, with the positive lead, and ground on a known good ground and depress the brake pedal.. it should read 12v. hope that helps best thing to do is check with scan tool. My snap-on gives me a real time readout of what each wheel speed is so its easy to see if its a bad abs sensor. also check the wires from the front hubs, trace them back to the abs computer and make sure there isnt a broken wire, gms are notorious for that.. u should be able to find the pin outs on the abs computer from a haynes manual or i can check my alldata account for you...

 

As far as codes, would there be a check engine light. my check engine light is not on. I have a haynes manual so i should be able to get the proper pin out. thanks guys for the replys, very helpful.

 

Your ABS light is on telling you that there is a problem with the ABS system. The ABS system stores trouble codes for itself like the PCM does for the powertrain. Two separate systems accessed via a common diagnostic link.