Reverse light issue?
 

I have a 1970 911 with reverse lights not working. Tried to resolve and get so far but a bit stuck. Fuses are ok, bulbs are ok, new reverse switch fitted. There seems to be no power to the switch however. I can take a live from the rear fuse panel and put it to the switch and the reverse lights come on, but don't go off when the gear shifter comes out of reverse. I'm no auto electrician and can't fathom out what it it. Ground? I'm happy to run a new lead to the switch but can anyone advise what goes where??? TIA

When you remove the two wires from the switch and touch them together do the lights come on? If so this should eliminate everything but the switch.

If they don't come on....power to the switch is sometimes on the same fuse as the hazard lights so checking the fuse connection is easy.

Did you put the washer back on the switch when you replaced it? The pin needs a little space here for movement.

When I repaired mine I had 3 problems to cure. Poor bullet connectors at the switch, a bad switch and a bad ground in the left rear taillight.
Good Luck!

Thanks Steve. The lights do not come on when the wires are touched together. I can't see a blown fuse in the panel but will try the hazards tomorrow to see if they work or not. I was hoping I could do a quick bypass and feed power from another source as I need a quick fix for now. I've had the tail light boxes out and can't see a poor connection anywhere and grounds look ok. Washer is on the switch but I think the issue is power.

Reverse light issue
 

If there's no supply (+) to the brakeswitch you need to check the connection at the 8th fuse of the upper 10 pole fusebox. (left side) This wire leads directly to the brake switch. If its connected , you should measure for continuity towards the brake switch. I hope this helped !

The 2 wires (supply and return) to the switch run through the engine harness 14 pin female connector.
In your test with a powered jumper, you may have been energizing the return line from the switch to the lamps.

Test to confirm continuity for each wire from pins 5 and 6 individually to the bullet connectors at the switch end.
Easiest way is to short (touch) the bullet connectors together and go across the female terminals at 5 & 6 with your meter and see if there is any resistance. Should be almost zero ohms.

If the engine harness wires check out, then it is power to pin 5 of the male 14 pin connector at the rear of the engine fuse panel that is the problem.
The power for the reverse lamps runs from fuse 8 up front, to the female 14 pin connector at the front of the rear fuse panel, then to the rear 14 pin connector.
Power to the switch in on terminal 5, out from the switch to the lamps on pin 6.

Reverse lights
 

Oops you are 100% right Timmy, i thought this was about the brake light My mistake.

Been there, done that myself. :)