[greg64]

Greg, use a jumper cable to tie the black meter lead to a good ground. Now, probe those spots with the red meter lead. You'll either get 12V or 0. The power for the backup lights comes from the ignition switch when in the run position. So you should get 12v on one of those two wires at the transmission connector. If you have 12, work towards the backup lights. If you have 0, work backwards towards the ignition switch.