I recently received a 2002 Chevy Tahoe with a completely stock sound system from the inlaws with a dead radio. I pulled the radio and tested the wires with a multimeter. I tested the keyed power (yellow) and I get a solid 12v, but the constant power wire (orange) is only getting ~.2v. I tried jumping the keyed power to the constant and the radio fired up and worked great.

Everything else electrical works great inside the car except for the radio. I can pull a constant power from something else but I really don't want to hack the virgin harness. I'm having a hard time tracing the constant power wire to find the problem. Does anyone know where the orange wire gets it's power? Alt, fuse box, amp, directly from battery?

 

It should be fused in the driver side fuse box in the dash.

 

Ah, that 10 amp fuse? I remember the fuse checked out as far as continuity, but I didn't check to see if the fuse was actually getting power. I'll check it tonight to see if it has constant power.

 

I checked that fuse and it gets switched power but not constant. It looks like the underhood radio and radio amp fuses are getting constant 12 volts. I'm kinda at a loss for why the radio isn't getting constant power.