Done a gear swap on my 05 sierra and the abs and brake light is on. It comes on after starting the truck and going down the road. Bought a tuner reprogrammed the tire size and gear ratio. I 'm at a loss!!! Has anybody had this issue before? Thanks!

Now that it has a hard code in the ABS it won't clear till it has seen no faults for 200 drive cycles, or you need to find someone who has a scanner that can clear the ABS codes.

What did you use to program it?

Is this truck 2wd or 4wd?

His bio says he put 35inch tires on. That would look tacky on a 2wd model, but I think I know where your going with this Rich. If he only changed out the rear gear, then the ABS is seeing a gear ratio mismatch between the front and rear causing a ABS light.

If so, then its highly suggested that the matching ratio be put into the front diff also. Otherwise, severe drivetrain damage can occur.

Yes Mike that is where I was going.

The truck is 4wd and yes i changed both gears!!!! Bought a hypertech tuner.

Would the right front speed sensor throw the light? I pulled that code.

Yes it would

The Abs system on this truck is not like the ses light on a vehicle. It will clear the light once the fault is no longer without several drive cycles.


The EBCM performs one initialization test each ignition cycle. The initialization of the EBCM occurs when the following conditions are met:

•The ignition is ON.
•The bulb check has been completed.
•Vehicle speed is greater than 6 km/h (4 mph) .

The initialization sequence briefly cycles each solenoid and the pump motor to verify proper operation of the components. The EBCM sets one or more DTCs in accordance with any malfunction that is detected.

The EBCM defines a drive cycle as the completion of the initialization sequence.

Did the light come on immediately after starting the truck up or did it take some driving?