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Random cluster errors, electrical gremlins?

1282 Views 22 Replies 3 Participants Last post by  cart7881
I have a 2011 Colorado 3.7 Z71 that has recently starting having very weird issues. after starting up to go to work the other day, my cluster started showing seemingly random errors, shutting down and coming back on, and will sometimes shut off completely showing only check engine and passlock lights. When it is like this, the truck will not start.

In troublehsooting, I found my AC resistor, harness, and blower all needed to be changed out so I did that yesterday as well as cleaned the two splice packs mount points (even though they looked perfectly fine). Also added a second ground from the splice behind the battery to the same spot the battery negative mounts to the body. It ran fine for 30+ min in the driveway while I put back together the glove box and cleaned up all the tools, plus a quick trip around the neighborhood, and multiple start/stops after. I thought it was fixed, then it did all the same stuff this morning when I was trying leave for work this morning.

Other notes and things I've checked from posts similar but not quite the same errors and symptoms:
Disconnecting the battery for 10+ minutes seems to get it to run normally for one or two more restarts, then it has the same problems.
Also opened up the passenger side splice and no corrosion.
I've owned the truck since 2012 so I know there's likely not any weird mods, botched fixes, etc.
No CEL/DTC show up on OBD scanner.
Cluster Errors: Brakes, Traction Fault, stability system, something about fluid, and a couple others I can't remember

Here's a video of the errors and rebooting cluster. Side note, low tire / tpms errors are normal, I've been too lazy to get the bad sensor replaced.
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Update on this if anyone can help:
Truck will only give me the CEL, no security light anymore, still no codes. It does sound like the fuel pump runs for a second and normal under-the-hood sounds when turning the key to Run but nothing happens when trying to start. Battery is good and has been on the charger while it was disconnected.
I've tried:
leaving the battery disconnected for a few days
leaving the neg cable disconnected and jumpered to the to positive for a few days
recleaned the splice pack mounts and added dielectric grease.
disconnecting negative and grounding each pin individually on the BCM and harness
thinly brushed on dielectric grease on BCM and Harness with nylon brush as described in that one service bulletin
There was a small amount of water under the carpet on both sides but i've since pulled it up and dried it out.
ground under passenger seat is good.
tried security relearn by leaving key in Run position for 10+ min multiple times.

I guess, are there other things to check? I think I saw something about the ignition cylinder and aftermarket radio (which I do have, installed probably 2013) but I wasn't fully understanding what to check with those.
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Shouldn't this be the other way around? Disconnect the positive cable to the battery and short it to the negative, or ground. I guess the effects would be the same either way......
I'm no electrical engineer but I would think it would have the same effect. I'll try it when I get home from work anyway. I'll try anything at this point.
When operating normally, when the key is turned on, you should see the CEL, Seat Belt, Battery, ABS, Traction and Airbag lights in the Tach display. After a couple of seconds the lights should go off, except for the CEL and Seat Belt. In the Speedometer display there should be Brake, Shift, Security and Oil lights and three should go off leaving just the Security light on. So, prior to starting, there should be three lights on, The CEL, the Seat Belt and the Security light.

When the key is turned to start the Security light and the Seat Belt light should go off immediately and the CEL should go out as soon as the engine starts.

I can see, in the video, that the lights are not operating normally when the switch is in start position. What is happening with the lights when the switch is in the run (on) position?

Maybe try swapping the Run/Crank relay with the RAP relay.
In the video, the truck was actually running. I can't even get it to do that anymore though. Now I have just the CEL and no other lights, nothing else happens in cab when putting in key, turning to acc, run, or start. turning from ACC to RUN to do hear fuel pump kick on for second or two and the normal clicking under the hood (relays? injectors? idk). Turning from RUN to START does absolutely nothing; no sounds, lights.

I'll try to record a new video when I get home.
You're going to need some test equipment. Do you have a test light or more preferable, a multimeter?
I do have a multimeter, and maybe a test light.
Do you have a diagram of what pins should show voltage or continuity to ground?

More info:
forgot to mention, all fuses were good.
headlights and key fob/power locks work.
Windows and radio do not work

here’s the video I took tonight.
Key in, nothing happens, not even chimes even though the door is open.
Acc, no change.
Run, CEL only but you can’t hear the fuel pump or anything else due to background noise.
Start, nothing happens

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@cart7881 thank you for the detailed write up! Unfortunately, all 3 wires showed about 12.4 volts.
Sorry, missed that yesterday. Just tried it, no change
12+ volts on both sides of all three. Also checked continuity across each fuse for good measure and they had 0 resistance. starting to sound like a bad bcm?
Been a while, here's an update. Cart7881 helped me do some troubleshooting leading to a likely bad BCM. Beginning of November, had a friend of a friend that's a mechanic hook up his expensive scan tool and check the BCM and data bus, he concluded it was a bad BCM and said he'd order one for me. Fast forward to a month ago. the BCM he ordered never showed up then he just stopped replying to me at all. Ordered a remanufactured BCM programmed to my VIN and mileage from and it is doing the same thing.

Current issue is the same as in the video on post #8. If anyone has any further ideas or recommendations, please let me know.
1. I have an aftermarket radio that was installed in like 2012/13ish. I do have orig radio I can put back if necessary
2. No dome light with refurb BCM. Yes, old one does have dome light
3. Parking and headlights work with switch for both BCM. Remote door locks work with old BCM but not new (expected until relearn fob on new BCM as I understand it)
4. Hazards flash, with cluster arrows, on old BCM, not on refurb*

black connector:
B5-8 all show 12v on both BCM with key in run
Both only 12v on B5 and 8 with key out

gray connector:
Slot 6 is unused, no wire/pin in connector and says so on wiring diagram
B7 and 8 have 12v with key on both BCM

*Side note, with refurb BCM connected, hazards and dome light will come on only one time for about 1 sec or 2 clicks of hazard randomly after connecting

Also, switching back to old BCM to retest dome light I had a situation I forgot about happening previously. The CEL and security light come on but also the AC blower. The odd thing is, the ac fan keeps running unless I disconnect battery or bcm. I just tried to recreate this but could not get it to happen again.
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Well cart, you’ve done it again. Put the factory radio in and it starts right up. Pretty sure this chime module is the problem…
Finger Gadget Automotive lighting Eyewear Bicycle part

send me your cash app/Venmo/PayPal or whatever. You definitely earned dinner or beer money or something
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