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97 manual trans reverse lights not working

S

schiker

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Pendleton, SC
My reverse lights aren't working and don't know how long they have been broken. Likely since had trans rebuilt.

The aggravating thing is I can measure 12V on on green wire at back of truck that is reverse lights power wire from transmission and again across terminals of circuit board but I guess its not enough power to light bulb. I tried all three of the bulbs and no lights (bulbs work other places and all check continuity). I also tried to use jumper wires to bypass the cirucuit board with no luck.

One big thing I forgot to test was jumper the reverse switch at the transmission.

Any other suggestions and what to test next besides the transmission switch? I measure continuity from black wire (ground) to bed latch.

My turn signals, brake lights, parking,and hazards all work.
 
you have a bad ground or bad socket. Is this one of the assemblies that the plastic area turns brown and looses the connections in the circuit board?
 
May be bad board but I can't use jumpers to go from truck gm weatherpack to bulb either and work but I didn't verify jumper worked on other light position. Jumper might not make good enough connection.

Next test will check other positions will jumper bypass the circuit board. Then jumper rev switch at transmission.

Back up lights and all other lights use same ground wire at back of circuit board but will clean it if I can find its termination.
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Dang its the switch in the transmission. I used a jumper to complete the circuit instead of transmission switch doing it and the lights work. One side I left the lense installed and the other side I took out circuit board and used alligator clip jumpers to bypass the circuit board both sides worked. I also cleaned the ground first and what made them come on was jumper at the transmission. Take out jumper and plug back into transmission and quits working.

Its dang tight to reach the reverse switch at top of transmission uhhhgg. Anyone change it out not taking the transmission out of truck? Is it doable? I am not sure how big the switch is and what is inside the case even if I can get a socket on it to unscrew it.

I don't know a toggle switch under dash seems like an ok thing right now. Or just add some off road lights with separate wiring and toggle switch as factory reverse lights aren't all that bright anyway.

Anyone install better reverse lights?
 
My brother changed mine out, it was bad when he picked up the truck.

It can be changed with the trans in the truck. Tight and difficult, yes.
 
By the way this is the 2nd time a Fluke meter has made me question diagnostics. It can beep continuity through a bulb filament and it reads 12V but doesn't tell you if it can carry a load.

Probably a test light would have been a better test tool and I wouldn't have chased and worked on circuit board so long as maybe the problem ( I cleaned and scraped the hard GM dielectric grease out and cleaned pins and was able to probe connection etc). The Fluke would be good for finding weak shorts ect.
 
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