Derek Zeanah

...and the bulbs seem fine, then it's likely a sensor in your transmission that turns on when you're in reverse. This is a $30 fix if you've got a manual, or apparently over $200 if you've got an automatic (a search will yield info on autos).

The only problem I had with this was verifying the location of the sensor. On th 2nd generation V6 4Runners apparently the 2WD manual transmissions have the sensor at the top of the left-hand side of the tranny; on the 4WD it's on the right around the middle.

Basically, it's an electrical plug that sticks out about an inch -- on my 4WD V6 it was the only electrical sensor that was easy to see and get to. You can check it by having someone stand at the rear of the vehicle, with the ignition 'ON' (though not running) and the tranny in reverse, while you bridge the connectors that hook to the sensor. You'll then know you've got the right thing.

OR, you could just unscrew it and look at it. A 1" wrench is a tad too small so I used a crescent wrench, but once you get it out you'll see a ball bearing in the tip -- the whole ball bearing and holder press in just like you'd expect a switch to do.

In my case the whole swap took about 2 minutes, once I'd diagnosed the problem and ordered the part.

Hope this helps someone. Biggest problem on my end was making sure I was looking at the right thing, and bridging it was the verification I needed.