JBJrC4

91 6 speed. So far I've checked the fuses on the passenger side dash and under the dash on the passenger side. I removed the reverse switch from the transmission and lubed and it up and exercised it, and still nothing. There's power going to the switch. No power going to the reverse lights.

MatthewMiller

The switches themselves can fail. Try an ohm meter across the two terminals. With the car in any gear other than Reverse, it should have infinite resistance. When you put the car in Reverse, it should have nearly no resistance. That will tell you if the switch itself has failed.

If it's working and there is power going to it, then connect a voltmeter or test light from the terminal that leads to the lights and see if power is coming out when in Reverse. Assuming it is (because you already tested with an ohm meter), then you will have to start tracing the wire back and seeing where it stops having power. You'd be looking for a short somewhere.

FWIW, I have that problem (functional switch but no lights, and the bulbs are good). I haven't started tracing the circuit yet, but that's in my future. I did look up the circuit in the FSM (for my 96), and it shows the circuit running up through the shoulder belt mounts. The previous owner of my car put a harness bar in and it bolts in there. So my first guess is that something went awry at that location.

billschroeder5842

I think it is your switch. My had the identical symptoms and with a swap I was good.

JBJrC4

[QUOTE=MatthewMiller;1596153615]The switches themselves can fail. Try an ohm meter across the two terminals. With the car in any gear other than Reverse, it should have infinite resistance. When you put the car in Reverse, it should have nearly no resistance. That will tell you if the switch itself has failed.

If it's working and there is power going to it, then connect a voltmeter or test light from the terminal that leads to the lights and see if power is coming out when in Reverse. Assuming it is (because you already tested with an ohm meter), then you will have to start tracing the wire back and seeing where it stops having power. You'd be looking for a short somewhere.

FWIW, I have that problem (functional switch but no lights, and the bulbs are good). I haven't started tracing the circuit yet, but that's in my future. I did look up the circuit in the FSM (for my 96), and it shows the circuit running up through the shoulder belt mounts. The previous owner of my car put a harness bar in and it bolts in there. So my first guess is that something went awry at that

Can I check the Ohms with the switch disconnected and see if it's faulty?

VikingTrad3r

on my 4+3 i just pushed the button in and checked fir continuity. not sure if your switch is similar in the zf. mine was toast and i got one from the local boneyard that tested positive for continuity using my voltmeter before i bought it.

JBJrC4

I remember doing that and it blew my 15 fuse.

MatthewMiller

Yes. You're literally just checking to see if the switch is physically closing the circuit when the tranny is put in Reverse.

ihatebarkingdogs' way should certainly work, too. If that is blowing a fuse, that's a problem. Off the top of my head (haven't finished my morning coffee yet!), that makes me wonder if there is a short circuit somewhere "downstream" of the switch. I don't know what else could draw enough current to pop a fuse in that circuit.

JBJrC4

ok so to check the switch with a multimeter what do I set it to to check the ohms? Also how many ohms should I expect?

VikingTrad3r

just put car in reverse. turn car off. get under car (safely!) and put multimeter on continuity, and touch each prong on the switch and the dvm should make a noise if the reverse switch is functioning correctly because its closing the circut.

on the pigtail, if you jump the two wires and the recerse lights come on then its the switch is bad. which you should be able to confirm by checking for a lack of continuity if (no noise from your dvm) while the car is in reverse.

but if you are blowing a fuse when jumping the wires on the pigtail, then somewhere on the wire that runs to the rear reverse lights, the hot wire will probably have a short meaning all the current that passes down the wires to the bulbs after the switch is pushed in, escapes to the chassis and you get an "free flow" amount higher than the 15amps and it blows the fuse.

IF THIS IS THE CASE then im betting your switch is fine and the reason your lights are not coming on is that the fuse is blown. id start by removing the plate and reaching in and getting the reverse lights out of the socket (i think its a friction twist fit) and inspect the lines for the short! you should see a spot with bare wire with a path for the electricity to free flow to a chassis location or something. When i found mine it was by the reverse light lenses. i took off the plate and removed the reverse light lenses and i had a nice open look

JBJrC4

Turns out the switch is bad. Thanks guys. Now I just need to find a new one

JimLentz

The switches can be an issue. I had no problem finding a replacement, but they come with a pigtail. The pigtail makes them harder to work with. My old backup switch was bad, but using a continuity tester would have shown it as good. When closed it read about 5 ohms, which is too high to turn on the lights. If all of the backup lights are functioning they draw 7 amps. I have wondered if switching the lights to LEDs would improve the life of the switch as it would have to pass much less current.

yakko684

Going to LEDs would definitely drop the arching inside the switch! LEDs are the way to go. You would not need to change the lights again. If I pull the reverse lights to replace the bulbs, I will put LEDs in mine. Oh yea, How hard is it to get the lights out? The manual says you need a tool to pull them.

Randy