Questioni bought a car that didn't have a stereo and i now i have to time to put one in but every wiring diagram lists things like 2 yellow wires one being the power and the other going to a speaker and leaves a few wires out. please help me figure this out. if you want a list of the wires that are there i'll make one up for you
AnswerHi T.J.,
I'm assuming that your Cavalier no longer has the original factory radio plug connected. If the plug is still there, then don't worry about the wire colors--just go out and buy an adapter harness made for your vehicle. This takes all the guess work out of the head unit wiring.
If there's no plug, then you have to figure out the wire colors. GM has used pretty much the same colors on most of their cars for decades, and I've worked on so many GM's that I can recite them from memory. However, when I'm doing wiring in one of these, I still depend on my multimeter, for the reason that you pointed out: GM uses the same colors more than once, for more than one function. In the end, the only way to be certain is to verify the wire function with a multimeter. You don't want to guess when it comes to power and speaker wires, because if you mix them up, you could damage your head unit.
You can use the cheapest multimeter in the world, as long as it has a DC voltage function and a "continuity" function. If you don't have a meter available, I'd suggest going out and buying or borrowing one before you do any wiring in the vehicle.
First, find the ground wire. This is usually black, or black with a white stripe. Test it by setting the meter for "continuity". The ground wire will show continuity, with very low resistance, when you touch the wire with one probe and touch the outer ring of your cigarette lighter with the other. Once you find a wire that works like this, turn the vehicle's parking lights on, and test the wire again. Sometimes an illumination wire will work like a ground wire, until you turn the lights on. The correct wire will show continuity with the lights on or off.
Next, set the meter for DC volts. Connect the meter's black probe to the ground wire you just found.
Look for the constant power wire. This should be orange, or orange/black. When you test the wire with the red probe (and the black probe connected to the ground wire) you should see a reading around 12 volts on your meter. If you don't find voltage on this wire, then check the 10-amp fuse labeled "INT LAMP" in the fuse box on the end of the dash. Once you find the wire, make sure you insulate it so it doesn't short out while you're working. The constant power wire gets connected to the yellow wire from the after-market head unit.
Next, identify the accessory power wire. This is one of the yellow wires. Turn the key back to the ACC position, and test both yellow wires for voltage (just like you did with the constant power wire). The wire that shows 12 volts with the key on will be the accessory power wire. If neither wire tests with voltage, check the fuse labeled "RDO" in the fuse box. This wire will connect to the new head unit's red wire.
You'll want to identify the illumination wires next. One wire should be dark brown, and the other gray. Again, there will be more than one of each color present. An illumination wire will test with DC volts when you turn the parking lights on. Make sure the rotary dimmer switch is in the highest position before testing. If your new head unit has an orange wire, it will connect to the brown illumination wire in the vehicle; otherwise, you're just testing for these wires so that you don't mix them up with speaker wires. Tape them off so they're insulated, and leave them disconnected.
You may or may not have a green wire with a white stripe. If it's present, it won't be used with your new head unit. Make sure it's taped off.
Now you just have to find the factory speaker pairs--each speaker will have a positive and a negative wire in the radio harness. You can test for speaker wire pairs using the continuity function on the meter, or a resistance function. Find the two wires you think are the speaker pair, and connect one meter probe to each. If the wires are connected to a speaker, the meter should show continuity between the two wires, with anything from 4 to 10 ohms of resistance.
Here are the speaker wire colors:
Front left: tan (+) and gray (-). These connect to the white and white/black head unit wires.
Front right: light green (+) and dark green (-). These connect to the gray and gray/black head unit wires.
Rear left: brown (+) and yellow (-). The after-market head unit wires will be green and green/black.
Rear right: dark blue (+) and light blue (-). Connect these to the violet and violet/black head unit wires.
The after-market deck will probably have a blue/white and/or a blue wire left over. These don't need to be connected to anything in a Cavalier. If there are any other wires from the new head unit--pink, yellow/black, light blue, etc--they can probably be left disconnected as well.
Hope this helps!
Brian
