Wipers and HVAC both start and stop working at the same time!
 

My wipers and HVAC blower stop and start working at the same time. Even when they are both working, if I turn the Blower setting up from low the engine starts missing. The miss gets worse with every blower setting with high being the worse. Lol I checked the ground to the Blower and it seems fine. Anyone have any ideas? This is quite the gremlin. :-)

Edit: It's a 1988 GTA

Re: Wipers and HVAC both start and stop working at the same time!
 

Somebody hacked the blower and ignition wiring together. Seems plausible, especially since both systems are in close proximity under the hood. Look for butt connectors or electrical tape.

Re: Wipers and HVAC both start and stop working at the same time!
 

What you probably have, is high resistance in some path that feeds power to all of those things.

Look for a bad connection somewhere; maybe at the bulkhead connector or ignition switch. Could be one of the fusible links as well. Basically, trace all the big red wires. A thorough study of your car's wiring diagram should locate which wires or parts such as switches & connectors carry 12V to all 3 of those things (ignition, wipers, HVAC), which you can then use your multimeter to find at what point the 12V suddenly becomes less than 12V as you start near the battery and probe further downstream.

Re: Wipers and HVAC both start and stop working at the same time!
 

Thanks guys! I found the problem. I turned the wipers on and started tracing the wires. Sure enough, I have a wire that's throwing some spark. I'll fix it when it stops raining and take a pic for future reference.

Re: Wipers and HVAC both start and stop working at the same time!
 

Problem turned out to be the stud/bolt for the grounds on the back of the driver side head gone. Now I need to find the right size bolt