So I bought an 05 Chevy blazer about 6 months ago, everything worked fine. A few weeks ago my heater core went and anti freeze leaked EVERYWHERE and then all of a sudden I started having very weird electrical problems.
When I start my truck the doors lock and unlock themselves, the back whiper starts going on its own, there is no head lamp and no lights on my 4x4 module nor does the 4x4 kick in when I hit the button. Also, my rear left speaker buzzes constantly for about 10 minutes. When I hit my door unlock button only the driver door unlocks and the lights on the 4x4 module flicker. Had it in the dealership but after $1400 later they couldn't pin point a problem. They said the rear whiper problem was due to the rear whiper motor being dead. So last night I put my rear whiper switch to LOW and tada the 4x4 worked! But I could hear a humming coming from under the hood but only while the whipers were on low , but I turned the truck off and tried turning it back on with the whipers still on low, BOOM head lamp flickers, doors lock and unlock multiple times, all 4x4 lights light up, speakers buzz like crazy and then nothing. Truck starts and runs fine but just so many weird elec problems. Could they all be tied in to the dead rear whiper motor? I'm out of ideas and options. Thanks in advance

 

The only thing i can think of is either a loose connector or a bad ground. I think there is a big connector on the passenger side under the dash. It would have been unplugged to do the heater core and may not be securely connected.

 

Any idea where all the ground locations are?