Basic wiring (what a radio needs to work correctly):

Yellow wire 12 volts Constant

Red wire 12 volts Ignition/Accessory

Black wire Ground

If you do not connect ALL of these wires the radio WILL NOT work.

Is the factory radio still in the car?

If so, this is a good place to start. Remove the factory radio to access the wiring behind the factory radio. There is usually a plug or harness coming from the rear of your factory radio.

Let’s find a constant 12 volt wire. Using your meter (set to 12v DC) or test light find a good clean metal point in the dash to secure the ground side of your meter/test light. With the key in the off position, probe and test the wires. Not all factory radios have a 12 volt constant wire; you may need to go to the fuse box, cigarette lighter or ignition harness. You should find at least one wire carrying 12 volts at all times.

Found one? Now turn the ignition on, then off; there should be no change. Also turn the headlights on and then off. If this wire stays at 12 volts then this is the correct wire for Constant (yellow wire).

Is the factory radio no longer in the car?

You will need to test at the fuse box, cigarette lighter or ignition harness. Some fuse boxes have “tabs” or spades that provide 12 volts constant as well as Ignition/Accessory voltage.

Using your meter (set to 12v DC) or test light find a good clean metal point in the dash to secure the ground side of your meter/test light. With the key in the off position, probe and test the wires or tabs at the fuse box, locating a 12 volt constant point.

Found one? Now turn the ignition on, then off; there should be no change and voltage should remain at 12 volts. Also turn the headlights on and then off. If this wire stays at 12 volts then this is the correct wire for Constant (yellow wire).

Factory radio still in the car:

Again using your meter (set to 12v DC) or a test light find a good clean metal point in the dash to secure the ground side of your meter/test light. With the key in the on/acc. position, probe and test the wires.

You should find at least one wire carrying 12 volts. Turn the key off. The voltage should go away. Turn the key back to the On/Acc. and Run positions and voltage should come back. This is the correct wire for Ignition/Accessory (red wire).

No factory radio:

You will need to test at the fuse box or ignition harness. Some fuse boxes have “tabs” or spades that provide 12 volts for accessories as well as a 12 volt constant.

Using your meter (set to 12v DC) or test light find a good clean metal point in the dash to secure the ground side of your meter/test light. With the key in the on position, probe and test the wires at the ignition harness or tabs at the fuse box, locating one wire carrying 12 volts.

Turn the key off. The voltage should go away. Turn the key back to the On/Acc. and Run positions and voltage should come back. This is the correct wire for Ignition/Accessory (red wire).

When you tested for the 12 volt constant and Ignition/Accessory wires you grounded your meter/test light to a metal point in the dash. You can use this point.

To test a wire for a ground set your meter to “ohm”, then place the ground lead of your meter to the negative side of your car’s battery and use the other lead to test the wire. You should get a very low reading around .1 or .3. Turn on headlights and ignition to be sure there is no change in the reading. This is a good location for Ground (black wire).