Back-Up Lights Don't Work

[Skyline-Tweak]

I noticed that my reverse lights don't work. I have read some other threads and most of them tell me that it could be a switch on the transmission. I'm assuming the switch would be one of the 4 sensors on my transmission. It's an automatic A604/41TE. The top two are speed sensors for input and output, but on the lower end there are two more sensors. One is the transmission range sensor and the other one is the Park/Neutral Saftey sensor. But I don't have a clue which one to test. I've read that they are the same thing but if this is true then why is there two of them seperated? Can someone please explain this better?

 

[1990TSIAWDTALON]

I have a 5 speed BUT, I believe all backup light wiring is hot and a switch just finishes the circuit by grounding, thus turning on the backup lights. I would test those other sensors with an OHM meter and see which one (if either) has a wire going to ground. If you find one, jumper it across to the other wire on the plug and with the key on see if the backup lights are on. I know that my switch on my trans just grounds the circuit and they work because I had to solder wires to the messed up backup light switch and connect them to the proper plug. Why? The El Cheapo backup light switch I bought at O'riellys twisted off in the trans so after finally getting it out i put the old switch back in. It didn't have a plug holder on it as the PO had broken it off but the switch itself still worked and alot better than the aluminum cheepy from the parts store. Two wires and a little solder on the lugs that were exposed on the old plug and my lights work great. Just a suggestion to try and figure out what turns them on on the auto trans cars. A Factory Service Manual would be a good investment, I have one for my car and you can find them on here or on eBay usually.

 

[Jeff420a_DSM]

I drive a 5-speed as well, and when i bought the car my back up lights weren't working, i too thought it was the back up light switch. But i was doing something to the car so for safe practice i disconnected the battery and low and behold i saw my reverse lights reflection in a car, so i was happy i didnt have to buy a new one. So maybe try resetting the whole system by disconnecting the battery and reconnecting it. But also check to see if you need the bulbs replaced. (it wasnt mentioned that you have checked them) Always check the simplest solutions before going head first on an assumption

 

[1990TSIAWDTALON]

+2 on check the bulbs

 

[Skyline-Tweak]

I checked the bulbs and the switch at the gear shift. I jumped the PRND2L sensor on the transmission and the one reverse light kicked on. The other one has power to it but doesn't light up. I read up more on the sensor and it says it helps to tell the car which gear it's in which would make sense because my car wouldn't start by key either.

 

[1990TSIAWDTALON]

Check the ground on the one that isn't coming on.

 

[AllanL]

check the contacts between the bulb and bulb holder.
a little sandpaper and some dielectric grease to help keep moisture away...