Aftermarket head unit troubleshoot (1 Viewer)

[kuruzaa]

I installed a Sony aftermarket head unit in my 80 around January of this year. All was fine until my alternator failed and I had to jump my car (multiple times). One of those times may have blown my radio fuse(s) with improper jump connections. I have since replaced the 15a radio/dash fuse that were blown and I also replaced the fuse on my head unit that was also blown. Reconnected the headunit and no response.

I plugged in the stock radio and it fires up fine, so now my attention is at the wiring harness and the head unit itself. I checked every wire in the wiring harness using my multimeter to check if there was any breakage or if I did a s***ty soldering job - all wires have a solid connection. I checked the red power wire when the car started on the wiring harness and that also came back fine.

So I thought perhaps my headunit was just fried - so I bought a new one. Connected it...then nothing.

This is where I'm stuck. What else can I check to diagnose the issue? Not an electrical expert so there has to be something I'm missing.

x-posting for more visibility.

 

[MoJ]

I installed a Sony aftermarket head unit in my 80 around January of this year. All was fine until my alternator failed and I had to jump my car (multiple times). One of those times may have blown my radio fuse(s) with improper jump connections. I have since replaced the 15a radio/dash fuse that were blown and I also replaced the fuse on my head unit that was also blown. Reconnected the headunit and no response.

I plugged in the stock radio and it fires up fine, so now my attention is at the wiring harness and the head unit itself. I checked every wire in the wiring harness using my multimeter to check if there was any breakage or if I did a s***ty soldering job - all wires have a solid connection. I checked the red power wire when the car started on the wiring harness and that also came back fine.

So I thought perhaps my headunit was just fried - so I bought a new one. Connected it...then nothing.

This is where I'm stuck. What else can I check to diagnose the issue? Not an electrical expert so there has to be something I'm missing.

x-posting for more visibility.

Does the head unit work when you power it directly from the battery?

 

[JoeW]

Did you use your same harness that is supposedly good with the new aftermarket deck?

 

[kuruzaa]

Fuse blows on the HU when testing. I must have a short somewhere...

 

[JoeW]

Sounds like your power and grounds on the head unit harness are backwards/ shorted. It might be time to rebuild that harness and verify your wire colors.