ABS Sensor

[im_deaf]

Howdy everyone, I have a 2000 GMC Sierra, Ext cab, 5.3L 4x4, I bought it a few months ago and have been fixing it up (usual repairs) and the abs light is on, my brother who is a former gm mechanic, ran the code and it points to the left front ABS wheel sensor, so we replaced it, cleaned/lube the connections, etc and the abs light is still on, code keeps coming back to the left front. We tested the old sensor and its almost in range of the new one so we figure that wasn't the problem. We checked for broken wires, grounds, still cannot figure out what is causing it. If anyone has any suggestions i'd appreciate it.

[jcmd]

From what I understand, more often than not it's the control module that's faulty. You may want to pull the ABS control module and check for cold solder joints and such inside. There are some YouTube videos that cover the module removal and repair. If you have the time, pulling the module and checking it out might rule that out.

 

FWIW, my ABS lights come on and off daily and have for over a year and I'm certain I need to fix the relay solder joints. I was too busy when the weather was nice to pull the module from the frame rail. Next year...

[im_deaf]

I will look into that, thanks jcmd, i'm hoping its something simple because those modules are over a grand here

[tbarn]

Put a volt meter on the wiring for the hub. The connector at or near the upper control arm. Volt meter set to ac volts. Hand spin the wheel . You should see at least 2-300 millivolts. 400+ is better. A lot depends on speed of rotation. When in doubt, check against the other side. They need to be similar.

[im_deaf]

thanks tbarn, will try that when it goes up on the hoist this week, as well as jmcd's advice. my brother is determined to find the culprit. he doesn't work for gm anymore so hes forgotten the little tricks in finding problems such as this. I will let you guys know what we find, any other advice's is welcome, i will keep checking. thanks again guys, much appreciated for your help, have a great christmas

[sahls01gmc]

Check the front wheel bearing. When the bearing has play, it causes the sensors to not read correctly. Mine did that when I pulled into a parking spot. Tight turn under braking caused the ABS to go off....that's how I figured it out.