Passat wagon backup lights not working

My backup lights aren't working and I don't know that they ever have in the 2+ years I've had the car. The fuse is OK and I've replace both bulbs.

Using a voltmeter, I checked at the bulbs and see no voltage. But if I remove both bulbs, I can see 12V at the sockets on both lights. As soon as I put a bulb in either socket, I can't see the voltage anymore. Sounds like a grounding problem.

Has anyone any experience with this same problem? Is there a troublesome area for the ground connection to the tailgate? All other electical components work (knock on wood) so this seems to be a localized problem.

It's probably broken wires at the switch on the transmission linkage. It's easy to find. Look down at the transmission, towards the front, above the starter. The wires are probably broken at the connector. You may be able to get a replacement connector or just solder the wires back on.

Good Luck

I checked the connector at the gear selector on the transmission and the wires are solidly connected. I can see how the wires could break because it's in pretty close proximity to the wiring harness and the wire gets a pretty tight kink in it to make the turn.

If I remove the connector from the gear selector and jumper across the 2 terminals on the connector, then the backup lights come on. So the wiring from the switch on back is OK.

I tried re-seating the connector and still no good so it seems the problem is either in the backup light switch itself or in whatever in the gear selector is supposed to be actuating the switch to tell it that the reverse gear is selected.

Is the backup light switch part of the top housing piece for the gear selector or a separate part? The manual page shows it as a "8 - Housing * With Back-Up Light Switch (F4)"

Has anyone been inside the gear selector to replace the switch or for another reason? There is an exploded view on the Bentley CD but I'd like to know the pitfalls before opening it up.

I know that the '86 Jetta had a problem with the backup light switch. The little plastic finger in the switch that made contact somewhere in the transmission would wear down. I haven't looked at the one on my Passat, so I can't tell you if it's the same system or not.

It's the switch, or the contact connection between the switch pins and the wiring sockets.
You have 12 volts at the lamp sockets, but how many amperes? A bad connection will allow voltage but not enough current to illuminate the filaments. I bet you checked for voltage with a digital meter. These are sensitive enough to pick up static electricity. They'd detect the 12 volts, but the lamps need a minimum current flow before they glow.
Check the tightness of the two "petals" in the socket that grip the pins in the switch. It may be possible to restore operation by tightening their grip on the pin or by slightly twisting each pin into a mild helix shape. Spray some contact cleaner in the electrical sections of the pin and socket.
Turn on the ignition (engine off). Put the transmission in reverse. Plug in and remove the connection several times with the reverse lights powered. The "make and break" under load often helps restore electrical current flow to resistive devices. Don't use the same "make and break" with electronic devices.

I did try re-seating several times to no avail but I'll try bending and cleaning to improve the connection between the connector and the switch.

When I had measured the voltage, I saw 12V when no bulbs were in the circuit but none when they were so that seems like a good case for the "volts but no amps" theory.

I pulled the top off the gear selector and it was pretty greasy inside. I checked the switch function with an ohm meter and it was closing properly when I pressed the button inside so the switch was OK.

I cleaned it up and re-installed and now the back-up lights are working properly.

I had simalar problem> It was my back up switch. Check the back-up switch wire from the gear box. This happend twice had it replaced when I had gear box stripped & serviced The second time I just left it broken.

It's nice to hear of a success!