Mike.Johnson

Hi all,
I've been browsing the boards for a number of years, recently created an account due to needing your expert advice.

I've got a 1990 Camaro Z28 with a 305 TPI engine.
This summer I'm experiencing a very weird glitch and was hoping for some advice (I'm running out of ideas).

When my car warms up (has happened randomly anywhere between 150F to 230F) it seems to have a short circuit. The engine runs rough, stalls and refuses to start despite cranking. When it cools off (5-15 mins) it fires right up and runs until it gets warm again.

Reason I'm confident it's a short circuit:
When the engine stalls the electronics go bonkers... relays start firing like mad under the hood and I can hear other sensors buzzing (IAC). The car seems to go in and out of "diagnostics" mode with the MIL light flashing a 12 and the primary fan spinning. (Basically going in and out of a grounded OBD connector state).

When it finally cools off, everything returns to normal and there are no actual MIL codes present or any other issues present.

When the car was going nuts, I tried pulling each fuse under the dash individually... nothing stopped the madness (couldn't locate a specific circuit that would stop the flickering of electronics). What did stop it, was when I pulled the main connector near the battery... I suspect this connector feeds my entire car though? Should I start tracing these wires? Where do they go (Orange and Red)?

Any advice is greatly appreciated. Faulty ECM? Bad ground? Short circuit only when a closed loop sensor kicks in? I'm at a loss as to where to start tracing/looking.

Some pictures showing the main connector that stops the short circuit. Tried playing with a ton of other wires under the hood as well as the main fuse box, and nothing stopped the flickering of relays/electronics.




Main connector plugged in, short circuit stops when unplugged. Car still has SOME power (lights/starter) but obviously won't run when disconnected.



Female end of connector, goes into the main wiring harness... red and orange wires, no idea where they end up.



Male end of connector. Goes to battery and alternator.