Abs help

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Kylerhcarlisle
Posts: 1
Joined: Sat Nov 21, 2020 7:39 pm

Abs help

Post by Kylerhcarlisle » Mon Nov 23, 2020 3:39 pm

I have been working on the abs brake for weeks now have ran new grounds and I have voltage at my abs module have replaced the module twice and I still get the same code U0121 lost communication abs module, please help!!
2012 chevy caprice 6.0 l77

smwalker
Posts: 1949
Joined: Mon Jul 29, 2013 6:44 am
Location: Azusa,CA

Re: Abs help

Post by smwalker » Thu Nov 26, 2020 11:31 pm

What you would want to do is hook up a scanner and see if you can communicate with the module. If not then would want to look for a break in the data lines. Most likely a bad terminal at one of the connectors is usually what we see,

here is the data wires diagram.
https://www.chiltonlibrary.com/content/ ... 662707.pdf
Is this a new problem? Like was it OK before and it popped up or did the car have the problem when you got it?
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White

smwalker
Posts: 1949
Joined: Mon Jul 29, 2013 6:44 am
Location: Azusa,CA

Re: Abs help

Post by smwalker » Thu Nov 26, 2020 11:43 pm

Here is a diagnosis on a jeep but similar tasks to do:
Part 1

Part 2
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White

smwalker
Posts: 1949
Joined: Mon Jul 29, 2013 6:44 am
Location: Azusa,CA

Re: Abs help

Post by smwalker » Thu Nov 26, 2020 11:52 pm

Oh and just to clarify. you are programming the ABS module each time you install it correct?
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White

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