P1780 on 2000 Toyota Camry

ABout 86000 miles on the car, get a P1780 failure code. I know what the code means, and have seen a few potential problem in forums online. Whats the easiest/cheapest way to figure out what actually needs to be replaced or fixed?

Asked by for the 2000 Toyota Camry
The code refers to a park/neutral safety switch malfunction. It may indeed be a "bad" neutral safety switch but check for a break in the wires in the wiring harness on the left trunk lid hinge 9peal apart the harness and inspect it closely, repair any damaged wires there.
I had exactly the same problem. Also had problem with the backup lights and also the Reverse indicator on the dash would light when pressing the brake pedal even though the gear selector wasn't in reverse. The break in the wires was found about three inches before the wire bundle coming down the left hinge joined a larger wire bundle in the rear quarter panel.
Thanks a million for your tip I had the same exact problem and sure enough there were three broken wires in the area cited in this report.

John Chrisney
2000 Camry - Noticed the license plate lights weren't working. Found 3 broken wires and 4 frayed wires at the left trunk hinge location. Clearly this is a problem spot as the wires must flex substantially here. It also appears that the wire bundle "saws" itself on the trim panel edge. I repaired them by adding about 3 inches of additional "loop". I also trimmed the top edge of the panel so as to not rub/saw it's way through the bundle. The check engine light & code P1780 is now off as a result.
Same as Anonymous, October 23, 2010, 08:25.
Another web has a Toyota tech saying that the harness is 99% the cause for P1780. codes.