I wired up my brothers stereo in his 1994 volvo 850. At the time, I knew nothing about wiring harnesses so I did everything one wire at a time. I got it working but the stereo can still run with the car off. If you turn the radio off, a small led stays lit on the front. My brother couldn't get his car to start this morning. Could this little light be drawing enough power to run the battery dead over night? Should he just get a wiring harness and hook wires up like that?
If the stereo runs even with the ignition turned off, then you have wired a continuous power supply to the radio instead of an accessory, and that will drain his battery. I always recommend using a wiring harness when installing an aftermarket stereo, as there is no way you can accidentally wire something wrong.
