Codes U0073 and P0300?

2009 PONTIAC TORRENT

3.4L • 4WD • AUTOMATIC

SHROMEN

MEMBER
1 POST

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.

Sep 18, 2026 at 3:46 PM

STRAILER

✓Experienced Mechanic
55,540 POSTS

Yep, I can help you, here is a guide to help with the wiring testing and the PCM ground and wiring diagrams. I would check the fuses first, also please go over this guide for the p0300 code:

https://2carpros.com/articles/automotive-engine-misfire-code-p0300-causes-and-solutions/

U0073 means the high-speed communication bus was turned off. If U0073 is only stored/history and communication with every module is presently normal, clear the codes and concentrate first on the active misfire. If U0073 immediately returns or several modules are offline, diagnose the network and module power supplies first. This guide can help with the wiring testing.

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

Let me know how it goes.

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