Chevrolet abs light, airbag light, daytime running lights always ON

ABS light, Airbag light, Daytime running lights always ON

Chevrolet BCM Issue

sure sounds like a loss of communication between the control modules. the tough part, the system is like the old christmas tree lights. if one of the modules go down, it can pull down the hole data stream. same goes with the serial data line. what is really needed to help isolate this problem is a GM tech 2 scan tool. if there is no way to get your hands on one of these tools, the only other option you have is, check each control module power and grounds. to make sure the wiring is good. next step would be to check the serial data line for any opens or shorts. I have even seen a control module pull down the system. any one of the control modules could cause this. and they are all quite pricey.

 

just had a thought, I have seen ground G110, which is the ground for the abs and 4wd modules cause a problem. there is some ground wires mounted on the left frame rail, just below the drivers door. make sure all these grounds are clean and tight. in fact you may want to unbolt the grounds, clean real well and reinstall and see what happens. here is a picture of the grounds.

(1) Frame

(2) Electronic Brake Control Module (EBCM) Ground (GNO)

(3) Manual Selectable Ride Ground (G302)

(4) Automatic Transfer Case/ABS Ground (G110)

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Another Possibility

usually with this many problems, i have seen a few of these that the wiring under the underhood fuse block get chewed up from critters. the first thing i would check is flipping the underhood fuse block up and inspect the wiring. pretty easy to check, if you don't see any problems with the wiring let me know and we will go a different direction



Remove the left fender upper brace.

Remove the electrical center brace cover assemble by lifting the cover (3) outwards to clear the tabs.

Push on the tab (3) so that the electrical center can be rotated on the studs located at (2).