Instrument cluster going crazy, no windows, no A/C, intermittent communication with one port?

DERBYKESS

MEMBER
2006 GMC SIERRA
6.0L
V8
4WD
AUTOMATIC
230 MILES

Got into my truck this morning started the truck like normal, all the sudden my A/C stopped working tried to roll down windows all it did was click and everything on my instrument cluster stopped working and the lights on instrument cluster were coming on and off. I replaced my instrument cluster, cleaned all the grounds under the hood and then had info come up saying engine reduce power and it stayed running when I turned the key off. I then replaced the ignition switch. Started it up was fine for about 5 minutes and everything started doing the same thing again. Would you recommend a PCM swap or BCM swap. I feel like I’m getting nowhere with this issue and growing more grey hairs. This is my work truck that I use to support my family and now I just can’t figure it out.
Thankyou I’m advance,
Clayton k

2 Replies

DERBYKESS

MEMBER
2 POSTS

Here’s a video of what’s going on.

Video (Click to make bigger)

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Wednesday, July 19th, 2023 AT 1:57 PM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Thanks for the video, it helps. I would check all fuses and then do a CAN scan to see if the BCM is bad, also we need to check grounds, you can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Here is a guide to help you check the grounds:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Here are four grounds that need to be checked. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on. If the grounds are good the BCM is bad, but the CAN should confirm the issue.

Images (Click to make bigger)