2003 4x4 4dr LS Blazer Cabin Electrical Issues
 

I perused the forums and only found one tread that has a similar issue as me and there was no responses to it. I have a 2003 4dr 4x4 Blazer LS. There's a gremlin in my blazer, I lose my auto locks but I can still use the lock button on my door. I lose the upper part of my instrument cluster, no temp readings, no fuel readings which kicks on the low fuel indicator, battery light on, seat belt light on, airbag light on, security light on. The radio head unit is inop. Here's the really interesting part of it. This all happens when it's cold or hot in the cabin. When the temperature in the cabin hits between 70-75ish degrees I hear the auto lock solenoid kick on, the instrument cluster goes normal and the radio turns on. Everything is working normal. Suggestions on finding this bugger is welcome. I took it to a dealership and paid $135 to be told they couldn't figure it out what it was after three days. I'm not good with auto electronics so I'm at a loss.

In most of the cases where weird electrical faults like this have come up, I have seen them trace back to a malfunctioning ignition switch. You can test that theory by testing the contact resistance of the ignition switch itself. I created a fairly comprehensive thread on that topic some time ago entitled Anatomy of the Ignition Switch. When those contacts start to get burnt, they can cause all sorts of weird things to happen. Testing should help either confirm that the ignition switch is at fault or rule it out as the culprit and help you move on to something else.