1999 sierra electric problems

[2tonesierra]

Hello all, I’m new to this website and I’ve had a problem that started maybe 2 days ago in my 1999 new body style Sierra with the 5.3. So I was on the way home and the gauge cluster shut off and only the rpm and mph was working, however the battery light appeared. 30 seconds later it went back to normal. So this morning I go to crank it up everything is normal, drive about 100 yards get out turn the truck off and get back in. Gauge cluster only has the battery light on, nothing else present. So I turn the truck off crank it up, it’s still not fixed. Try this two more times and it’s working normal. I get to my next stop and get out wait 3 hours before going back to my truck and I’m having the same problem again, however i can’t get it to go back to Normal. I also noticed that when it’s doing this my AC will not turn on and also my 4WD will not turn on.

attached is a video of my problem. 
 

Video

Edited July 20, 2023 by 2tonesierra

[dna9656]

I suspect poor connections in plugged (circuits using plugs) circuits. Age/corrosion could be causing intermittent connection(s) in the affected circuits OR the poor grounds (the bane of these trucks) that seem to be an overly represented problem on this generation of GMs.

[64BAwagon]

The plug on the back of the module is notorious for connection issues. Many of the solder joints in these units crack after some time. 

Like @dna9656 says. Check the grounds and the battery connections first, if that doesnt solve it I would pull the dash bezel off (move the shifter to low gear to give some room) and then remove the 7mm screws and check the plug by wiggling it.