The reverse lights on the 996 have been non-functional for a while, and today I decided to tackle the problem.
Fluke multimeter in hand, I opened up the tail lamps and checked the bulbs. Both bulbs are good. Next I checked for voltage at the sockets while the car is in reverse. No voltage.
Next, back the car onto some ramps and crawl underneath to find the reverse switch on the transmission. Car sits so low to the ground, that even on ramps, my nose is touching the underside of the car. Tight sqeeze, but I crawl over to the gearbox. Of course there are a dozen little torx screws that hold the plastic panels to the underside. Crawl back out, clean the dirt off my nose and face, grab the torx drivers and crawl back under.
After a few contortions, I get all the screws out and remove the panel. Of course I get a face full of sand and gravel as I'm moving the panel out of the way. Now to find that pesky reverse switch.
Found it, front right corner of the gearbox. I unplugged the connector and checked for voltage at the terminals. Got voltage at the connector! Hmmm lets remove the switch and test that. Looks like about a 17mm? Crawl out from under the car, clean off my face, grab the 17mm wrench and stuff myself back under. Shit. It's a 19mm. Crawl back out, grab the 19mm, crawl back under. Remove the switch, crawl back out, and test it with the multimeter. Hmm, switch seems to work just fine.
Maybe it's a gearbox problem, and the part inside the gearbox isn't pushing the switch? Crawl back out, get a pencil, get a helper, and crawl back under. Put the pencil into the transmission switch hole, then have the helper shift into reverse. Pencil pushes up. Ok, so that's working. WTF else could it be??
Maybe the connection to the switch is loose or dirty or something? Put the car in reverse, crawl back under, and try pushing the reverse switch with my fingers, while a helper watches the lights. No lights.
All the components are good, why the heck aren't the lights working??
Now I'm 2 hours into it, pissed off that I can't figure this out. As I'm sitting there considering just taking the car to a shop, to let them sort it out, I remember the 996 has an absurd number of fuses in the fuse box. There can't possibly be a fuse, just for the reverse lights? Can there?
There is. And it was blown. Changed the fuse and everything works.
