Tip: Aftermarket radio installation
If you are installing an aftermarket radio and are using a wiring harness (such as Metra Rodeo/Passport) to help speed up the wiring you will need to do the following...
Check to see if there is a matching ground wire (black) on the factory harness. By matching I mean trace the black wire on the aftermarket plug-in harness towards the factory harness. Is this wiring going to anything on the factory harness?
If not, clip the black wire at the aftermarket harness. Next, extend this wire (strip, solder and wrap). Put on a spade connector at the end of the extended wire and attach the spade to a good ground. You can use the metal bracket to the right of the radio cavity (secure with radio mounting screw when you reinstall the radio). I did a continuity test (from battery ground) on this metal frame. It's a good ground. If it doesn't work for you for any reason, use a volt-ohm meter and do continuity tests on possible grounds.
If you don't know how to do a continuity test: connect one lead of the meter to the negative post on the battery. Touch the other lead to possible grounds. Most meters give out an audible "beep" when there is continuity.
If you don't do the above, you will hear buzzing or whine through your speakers (engine noise). I tore the interior apart twice thinking it was a ground loop problem before realizing there was no ground connected at the radio. Would've saved me hours if I had known!
