backup light does not work
 

Hi,

Was trouble shooting my backup light last night. (1979 930)

Backup switch work fine on transmission.

From what I can see, pin 5 & 6 is used on the 14 pin connector, where 5 comes from fuse box and 6 goes to backup light.

I measures no current on pin 5, so I guess it is some place between 14 pin connector and fuse box.

From what I can see from diagram, it should be a green/yellow cable.

Could not find this color going to the fuse box.

Also tried to make a jumper cable from another pin that had current to pin 5, just to test, but even then the light did not work.

I tested the connection between pin 6 and the tail light backup light. there was connection.

Any suggestions?

I know this likely sounds really dumb, but make sure you physically pull out the bulbs and check them and the sockets. I've had lights fail before where upon inspection the filament looks fine, but it won't light up.

Check the simple stuff first...

Did the failure just happen, is this a new vehicle for you, etc?

To determine if it is a problem in the engine harness wiring or in the car body wiring just pull the rear 14 pin connector and jumper the male pins 5 & 6 on the rear fuse panel with the key in run position. If the reverse lights work, the problem is in the harness on the engine or the switch.

Grey/brown may be the color of wire on the front fuse panel to look for, it should be fuse 11 for the reverse circuit.
The people building harnesses interchanged the green/yellow and grey/brown for reverse all the time...
(Or, the junior engineer that made the drawing got it wrong) :)

Bulb works fine, no power is coming to the bulb

had the car since 2011, but honestly do not remeber if it was working before

Thanks Timmy, will look for the Grey/brown and go from there :-)