[Tommy]

FWIW, when troubleshooting 12v electrical problems I'm a big fan of using long jumper cables (not the battery kind, but simple 12 gauge wires with alligator clips on each end). For example, for a fan hook one jumper cable from the battery ground (negative) post to the ground connection for the fan. Next hook one jumper cable at the positive connection for the fan and then momentarily touch the other end to the positive pole of the battery. If the fan runs, its ok. Then disconnect the negative jumper and repeat the test. If the fan runs its ground is ok. I now know the problem is in the power source upstream of the fan. As a relay also needs a ground, you can repeat the test there with the ground jumper cable. For other testing I use the ground jumper and either a test light or multimeter to test for +12v when various switches are on and power is to be expected at a given connection.