I'm trying to fix the backup lights on my 79 Bronco. 1156 bulbs are good. Grounds are good because tail/brake lights and marker lights work. I have continuity between reverse light sockets and between the rev sockets and the connector underneath by the rear bumper. I can not find the backup switch on the transmission.
Which is more likely to be bad, the NSS or the backup switch? OR should I be looking at something else? C6 automatic, 351m
Thanks for your help.

 

It's the same switch, two functions, one switch. 78-79 should be on the side of the transmission, where the manual selector arm is.
If it's not there then I would say that's your problem.

 

On the drives side of tranny. Remove the "J" arm, then remove the two small bolts, then slide it off the shaft. Disconnect the wire connector. Install in opposite order.