radio wiring

[Johnyd2]

i bought my 94 formy a couple weeks, and the radio was "bad". Turns out the car has some serious issues with its wiring being hacked and rewired incorrectly behind the radio. I cant get power to the head unit... any ideas or hits or advice would be greatly appreciated. P.s. im using a aftermarket reverse harness that fits the OEM radio minus the wires for the steering whell controls.

[MN6WS6]

There should be two power sources, one a constant 12 volt wire for station and clock memory (GM harness color is orange, aftermarket harness color should be yellow) and one from a switched ignition source (GM harness color is yellow, aftermarket harness color should be red). Check your fuse boxes to make sure the fuses aren't blown, as it's very common when a harness has been cut. Also, check your ground wire to make sure it is connected (GM harness is black, as is aftermarket harness). Those 3 wires should be all that's needed to at least get the radio to turn on.

The left rear negative speaker wire is also yellow, so make sure you don't hook those two yellow wires up backwards. Also the left rear positive speaker wire is brown, and most GM harnesses use brown for the illumination wire for the radio. The best way to solve this is to make sure all your wires aren't touching anything and replace any blown fuses. Use a multimeter or test light, find the orange wire and hook it up to the new harness first. Then turn the key on and find the yellow wire and hook it up second. Finally find the brown wire that shows voltage when the headlights are turned on and hook it up (or protect it if your using an aftermarket radio with no illumination control built into it). The remaining yellow and brown wires are your speaker.