Codes U0073 and P0300?

2009 GMC SIERRA

120,000 MILES • 5.3L • V8 • 2WD • AUTOMATIC

EARL91

MEMBER
89 POSTS
FOLLOW

Please help. need the engine ground wiring diagram or really the all of the engine wire diagram to the PCM. I'm thinking it has a bad ground or some sort of issue the wiring somewhere. i just can't figure out were. i don't know what wires are what. Please help. thank you.

Nov 9, 2023 at 8:55 AM

STRAILER

CERTIFIED EXPERT
53,854 POSTS

U0073: This is a diagnostic trouble code (DTC) for "Control Module Communication Bus 'A' Off." It means that there is a general communication problem on the CAN (Controller Area Network) bus A of your vehicle.

P0300: This code stands for "Random/Multiple Cylinder Misfire Detected."

Here is a guide to help you test the wiring round connections to the engine and it shows how the PCM is wired:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the images below. Let us know what you find.

Images (Click to enlarge)

Nov 9, 2023 at 10:38 AM