maxstead

Condition:
- Service ABS
- Service Traction Control
- Extreme rough idle (spoiler: as if all driver side cylinders not firing)

My Fix:
- Check to see if the coil packs are working on the driver side.
- with vehicle running, I pulled off spark plug wires one at a time and noticed no difference, so ended up pulling all wires off driver side all at once and still no difference.
- that indicated no driver side coil pack were firing (even though truck ran albeit roughly)
- checked for ground at the connector between the front and rear pair of coil packs and there was no ground
- installed a fresh ground to the black wire in the connector and everything works again. Hoping that I didn't introduce a ground loop.

I am having a few other issues (auto level, backup camera, clock) that could be explained by a bad ground, so wondering if they were all related. I fixed the one issue with my added ground, but will start to search now for perhaps a bad ground block or wire that may be causing grief to my other systems.....

Just sharing.

mountainmanjoe

Did you ground it to the engine block?

Check the ground strap from the engine block to the body. When they're just naked braided copper they tend to rot out.

Gumby22

Just FYI - pulling the plug wire is a quick way to ruin coils. Without a path to ground through the plug (or a spark tester), the coil can track through itself to get to ground, creating a short between the primary and secondary windings. With COP, just unplug the harness connector - it cuts power and ground to the coil and you’d have known just the same that those cylinders weren’t firing.

maxstead

No, I grounded it to a ground post on the firewall driver-side.

mountainmanjoe

Grounding to the engine block would be better. The pulse currents through the body could cause some problems.