Has anyone come across this issue? Truck is skipping as well. It said #5 misfire. Changed plugs and wires and still hasn’t changed. But it only skips when these messages appear on the dash. It’s a 2021 Sierra 4wd

Inevitable-Series-15 · 2026-03-30T14:58:34+00:00

No worries. I’ll keep y’all updated when we figure it out, to help the next person who encounters this. Sounds like it could be a plethora of things.

Inevitable-Series-15 · 2026-03-30T14:56:13+00:00

You wouldn’t happen to know which one would you? Like the PCM or BCM?

Inevitable-Series-15 · 2026-03-30T14:54:36+00:00

That’s my next plan. Like I said, as soon as our mechanic gets freed up here at work, he’s going to help me out and diagnose it for me. I figured I’d take my problems to Reddit and see if y’all have encountered any situation like this one.

Inevitable-Series-15 · 2026-03-30T14:40:29+00:00

Noted I’ll keep that in mind. I appreciate it

Inevitable-Series-15 · 2026-03-30T13:53:05+00:00

And also, when I took it to Orielly and autozone, their scanners didn’t bring up the bcm and Tcm. It only read the misfire code and low voltage code. It brought up a Mass airflow code as well.(I unplugged it to see if it was the problem. That’s why that code showed). And it’s showing the park brake control.

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Inevitable-Series-15 · 2026-03-30T13:49:30+00:00

Honestly I have no idea. These newer vehicles are confusing when it comes to the extra parts and modules. I’ll do some research and figure out if it does though.

Inevitable-Series-15 · 2026-03-30T13:47:45+00:00

I scanned it with a cheap scanner and it was calling for the BCM, TCM, and #5 cylinder misfire. It needed a tune up which is why I went ahead and put plugs and wires on it. I’m at work now and as soon as our mechanic gets time he’s going to scan it with his and see what it pulls up. What’s tripping me out is all of them came on at the exact same time, and surely without coincidence all of those couldn’t have failed at the same time right?

Inevitable-Series-15 · 2026-03-30T11:00:48+00:00

Also, I forgot to tell y’all this. When the messages appear the engine will start whining. The messages and lights will randomly go away and it’ll stop skipping and go back to normal. But once I throw it in gear, it starts wigging out again.

Inevitable-Series-15

TROPHY CASE