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Discussion Starter · #1 ·
Before posting this thread, I did search but found half completed/replied to posts about my current issue.

2014 with a 2016 front clip
Reconstructed title
Purchased over a 1 1/2 years ago without issues until now

Issue:
Power Steering Drive With Caution on the DIC. No power assist whatsoever.
Went to check the PSCM (power steering control module) because it is electronic assist not Hydraulic. Plug a little wet with fluids.
Looked up, Water pump leaking from the weep hole
Looked down, Transaxle leaking near the 4WDA (4 wheel drive actuator) that I replaced about a year ago and had no issues with since, but is now leaking in that area.

All this is close to and near the connection to the PSCM which leads me to believe the leak may have caused the issue, but not 100% sure!

Traction Control light on
Brake Light On
ABS light on

U0121 codes:

ECM (Engine Control Module) - Lost communication with the EBCM (Electronic Brake Control Module)
TCM (Transmission Control Module) - Lost communication with the EBCM (Electronic Brake Control Module)

Its going to the dealership on Feb 1st for diagnostic.

Was hoping someone might have gone through the same thing and found a fix for it. I dont think its the ground by the dash speaker. This just seems out of the blue and will more than likely cost a lot of money to diagnose and repair as small shops will not have the proper scan tools/programmers to properly fix this issue.

TIA!
 

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Discussion Starter · #2 ·
I guess nobody else had this issue, but if you do, I found the fix.

Issue:
Power steering stops working and the DIC states: Power Steering Drive With Care. The Brake light illuminates, the traction control light illuminates, the ABS light illuminates.

Codes:
U0121-00 - ECM Lost Communication With Electronic Brake Control Module
U0121-00 - TCM Lost Communication With Electronic Brake Control Module
P2544 - Transmission Torque Request Signal Message Counter Incorrect
U0073 - CAN Bus Communication

I made an appointment to drop off the truck at the dealership at $170/hr to diagnose the issue, but being broke and living check to check, I decided to trace it down myself. I'm glad I did. Since the main issue started with the power steering, I decided to start there and take a look at the Power Steering Control Module. I traced the wiring to the main plug that goes to the battery. I pulled the plug connection apart and saw some pretty good corrosion going on.

I used electronic cleaner, and a PLASTIC bristle brush to clean inside the male part of the plug. Reason being is power is still going through it and one side is + and the other - so you want to make sure you dont short that out. You can disconnect the battery if you want to, but I didnt.

I then sprayed and cleaned the female end and used a brass brush to get inside of the contact points and clean it well enough until I can buy replacement wiring. This is obviously the before photos. I then applied dielectric grease to prevent corrosion from happening again until replacement.

The replacement parts from GMPARTSDIRECT:

Alternator Battery Control Wiring Harness: Part #84220783 $112.64
Power Steering Control Module Wiring Harness: Part #23231301 $111.78

Steering control is back and all lights on dash are gone and codes cleared. Hope this can help someone else down the road!



Automotive tire Orange Bumper Electric blue Watercraft

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Hand Arm Leg Automotive lighting Gesture
 

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2003 Silverado 1500 LS
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:oops:
Nice find! Thanks for posting. Those connectors are 'supposed' to be waterproof. Perhaps during the clip exchange process the connector was left exposed to moisture and it corroded, who knows. Anyway, great find.

And the dealer charges $170 per hour? Holy crap. That's almost as much as my doctor. :oops:
 

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Discussion Starter · #4 ·
:oops:
Nice find! Thanks for posting. Those connectors are 'supposed' to be waterproof. Perhaps during the clip exchange process the connector was left exposed to moisture and it corroded, who knows. Anyway, great find.

And the dealer charges $170 per hour? Holy crap. That's almost as much as my doctor. :oops:
Thanks! Seeing the silicone gasket inside of the plug had me thinking the same: Waterproof, but you may be right. It may have been left unplugged for quite some time during the previous owners swap. I'm just glad I was able to find the issue and not go through the great expense of having the dealership give it a go. And yes, $170/hr. Pride Chevrolet in Lynn, MA. o_O💸💸💸
 
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