GMC Troubleshooting Questions? Ask a Mechanic for Answers
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The only one of those that is relevant is the misfire code. The other two are just some sort of glitch some less expensive scan tools have. Whatever the case they have no meaning to you.
Do you need help with diagnosing the misfire code?
Well the first thing to try is to swap the number 7 coil with another cylinder. A bad coil is usually the issue and swapping it with another known good one will cause the misfire code to switch to that other cylinder if the coil is the issue. Swap the coils, clear the codes and drive it till the check engine light comes back on and recheck the code. If the code is for the cylinder you swapped coils with replace that coil.. if not let me know and we can move on.
Let me know if you need anything further and please be sure to rate my service so I get credit for helping you today. Thanks
Sounds good. I will be standing by.
How did you check them?
OK The next step would be to either check for an injector pulse with a noid light or listen to it with either a stethescope or rubber hose or something and see if you hear it clicking,