did someone just direct wire it into the car, instead of wiring in the correct plug? If so, looks like you'll want to start there. If missing the stock plug, may want to hit a salvage yard, and cut you a factory connector (with as much lead wire as you can, so you have plenty to splice with). THEN, get yourself an aftermarket matching plug, so you can wire the aftermarket plug to the radio itself. Now, you can simply plug them together. If THAT doesn't fix your problem, you've got some under-dash wire tracing to do. Good luck with that