Originally Posted by iHackDifferent

Hello Group! I am having the same issue, however mine was killing my battery, after I turn off the truck with keys out and door shut. 10 seconds later the Hi Beam indicator light in the cluster will come on and act as if it going in and out, also the time on my stock radio would keep cutting on then turning off. So if my truck would sit for a couple days the batteries would be dead. So I took the radio out and it seemed to stop draining my batteries. Could this be a Security thing? Or the BCM? Thanks in advance! It is a 2005 Silverado 2500hd 108k

Originally Posted by Gumby22

The GM diagram(s) are attached.

The cluster only controls the on/off function of the high beam indicator. It receives the command to turn the indicator on/off from the BCM which monitors the multifunction switch for driver request.

If the power & ground feeds to the cluster are good, try pulling the fuses for the headlight circuits one at a time and recheck for the indicator after each one. There’s 2 fuses per each side - 1 for brights, 1 for dims - there’s also 1 fuse for the DRL circuit and 1 for the fog lamps.

If it doesn’t go out after the headlight fuses are pulled, try also pulling the fuses labeled “TBC” & “TBC IGN 1” as these are battery feeds to the BCM. Note that your truck may not be equipped with both TBC fuses depending on vehicle options.

If the indicator goes out after removing a specific fuse, suspect a short circuit and/or faulty BCM.

I can provide further diagnostic steps if needed.



2006 Silverado 1500 5.3



2006 Silverado 1500 5.3

Originally Posted by TMG007

I tried sending you a message. The system won’t let me. I have some questions regarding this issue. I just got done putting a 2000 LQ4 6.0/4L80E in my 2006 single cab 4.3/NV3500. I’m using the harness for that motor. I just repinned it to match the C2 connector on the fuse box. I got it running, all gauges work except oil pressure (I’ll revisit that at a later time. I have a manual gauge for now.) My bright lights indicator is one after I turn key off and pull it out. If I pull the lever to turn them off, indicator goes off, but then comes back on after a few seconds.

Originally Posted by Gumby22

Did you also replace the fuse block as well? Because The drivetrain swap shouldn’t have affected the lights - the lights are pinned at C4 of the under hood fuse block.

The diagrams already pictured should be the same for your truck in terms of lighting control, so the cluster is relying on a signal from the BCM to turn the indicator on & off.

Based on your description of the issue, I suspect the dimmer switch is shorted. The easiest test would be to unplug the switch and see if the indicator stays off. If yes, replace the switch - if not, the next step is to unplug C3/C4 at the BCM and recheck. If it’s out, the BCM will need to be further tested - if not, the cluster is likely malfunctioning but the power & ground circuits need to be checked before it can be definitively blamed.