This has got me pretty confused. The other day I was driving and the radio shut off. No big deal this is something its done for a while. This time though, the guage cluster became erratic with the needles going all over the place and all the lights flashing. Vehicle was running fine throughout this. I get home and turn it off and on a few times to see if I can replicate this. First few times the cluster is going crazy and it doesn't want to start. It does revert back to normal after something like the 3rd time running it. A few days later I try again. Everything is fine and I run a short errand. Before I shut it off I check the voltage gauge on the dash and it reads normal. I return to start my car and I get nothing when I put the key in. I could wiggle it around and get the occasional door chime. Pulling the key out made the needles move erratically and make strange sounds for about few min. I try a few more times and I just get dancing gauges and occasionally a flickering dash light. I got a tow home and inserted the key again. Everything is back to normal but my battery is almost completely drained, so no turn over. Not even enough juice to lock the doors. The battery isn't all that old either. Any ideas where to start? 2003 S10 Blazer.

 

The gauges, cluster and the ignition components get their power from the ignition switch. I would test the voltage coming into the following fuses when its acting crazy to start narrowing down where this is originating:

Input to (power from the ignition switch):

Gauges fuse 4, 10A IP fuse block
Cluster fuse 10A IP fuse block
ECM1 fuse 15A UHFB
Eng1 10A UHFB

and output from (power to the ignition switch):

Ign A fuse 40A UHFB

an alternate to this is getting under the dash and probing the ignition switch input and output power wires but I would rather just pull some fuses with a voltmeter and save my back. if the ignition switch comes up suspicious at the fuses then you can probe under the column to confirm. If it comes to that I have a good video.

Oh and welcome to the forum, it's ignition switch week.

George