ABS U0121 2011 CAPRICE

[Dieselroyalty]

2011 Caprice
Stabilitrack , park brake, abs light up on dash. Code U0121, no communication. I have checked the ground at pass head, good. connectors all look good abs circuit. I have 12v and good connection ground circuit at connector. Should i condemn module at this point? And if so how do I go about replacing and programming to vin? Is there a way to bypass abs altogether? Anybody replaced their abs module ??

[JoeR]

that ABS Module has 6 wires that come/go with communication data. If you have a lab scope, it'll make diagnosing it WAY easier. If not, you can find wiring problems by testing the voltage and resistance of all those wires. If it's not wiring, and it's a module, you're going to either get a scope or guess at it.
And to confirm what you already know, the EBCM need to be programmed after it is replaced. I think you're going to need to take it someplace that can diag and repair it.

Joe

[Mooseman]

If you do need to replace the module, it might not need to be reprogrammed if you get a used one from the same year and engine. It will definitely need to be programmed if you get a new or rebuilt one.

[Dieselroyalty]

that ABS Module has 6 wires that come/go with communication data. If you have a lab scope, it'll make diagnosing it WAY easier. If not, you can find wiring problems by testing the voltage and resistance of all those wires. If it's not wiring, and it's a module, you're going to either get a scope or guess at it.
And to confirm what you already know, the EBCM need to be programmed after it is replaced. I think you're going to need to take it someplace that can diag and repair it.

Joe

Thanks for insight. I will get labscope and check it out. Tracing wiring will be a pain I imagine.

[Sanford]

You will be required to do some reprogramming if you install a used one. About every module on these cars are VIN coded.

[Dieselroyalty]

You will be required to do some reprogramming if you install a used one. About every module on these cars are VIN coded.

And what do I need to program module to my vin? Is it relatively simple? Any leads on who can help or fix my car Dallas Tx

[Mooseman]

You would need a dealer level or high end scanner or interface and an ACDelco TDS subscription to get the calibration info.

[Dieselroyalty]

I’ve ordered obd sync from Aus to unlock radio. I saw the video say it can reprogram all modules on our vehicle. I will try communicating with that software see how it goes. Waiting on shipping. I’ve gone in there with HP tuners, saved entire calibration. And write entire, ABS issue went away for 5 mins then came back …. And as I’ve said before when I unplugged the abs module and tried to start car it didn’t even crank.