Backup Light Switch Replacement

[Conejo_K10]

I have a 75 K10 with an SM465. And I need to replace the backup switch which is located near the top of the trans.

I attempted to get a few 7/8" tools on it and nothing fit. I can get a 7/8" deep socket on it but not the ratchet. Can anyone suggest a tool of method to remove the switch? I'm hoping I don't have to pull the carpet and trans tunnel cover.

Perhaps another option is to buy a socket and grind some flats on it or shorten it.

Investigation: I was wondering why the fuse for the turn signals kept blowing. I found that the back-up lights are on the same circuit. I checked the lights, they were fine. I checked wires to the B/up switch and they were hot. This indicated a short in the switch. I unplugged the switch and circuit now doesn't blow the fuse.

 

[Turbo4whl]

7/8" deep, 3/8" drive socket could be a little shorter. Then use a flex-head 3/8 drive ratchet.

I would want to make sure the switch was shorted. Could be the wire from the switch to the lamps could be a problem or the bulbs and bulb sockets.

 

[Conejo_K10]

Thanks... I just ordered a 7/8" sensor socket which has a hex end for a wrench. Hopefully it'll do the trick.
re: switch; see investigation above.

 

[AuroraGirl]

Thanks... I just ordered a 7/8" sensor socket which has a hex end for a wrench. Hopefully it'll do the trick.
re: switch; see investigation above.

the wires being hot doesnt mean there is a short on the switch. the wires could have a short to power against themselves or from another live source.

Beings the wires find their way to the top of te transmission, do not discount them getting insulation rubbed through or pinched against the body especially with a bad t case mount.

You should verify the switch wiring to and from the switch for integrity, plus you should be able to test the switch, yes? with a multi meter to see if it has radical behavior against your expectations

edit i didnt see you said you unplugged. when you unplugged, you may have disrupted any wiring issue by moving the source of a potential short to power or ground out etc, can you visibly confirm under the truck or from inside at all the routing of the wires and if they appear damaged or rubbed

i say this because if you have issues gettngi to the switch you may just appreciate the time spent verifying if it turned out to be the wires had a friction rub where they lay on eachother not easily visible and possibly not always in contact, just a thought

 

[Conejo_K10]

Thanks for the input. My wiring is in fairly good condition considering the age, however anything is possible.

For the record, I'm very familiar with troubleshooting, I work as an electro-mechanical Engineer and have an aircraft mechanic/technician A&P license. With that said I have worked on cars, trucks and aircraft for over 25 years.

 

[AuroraGirl]

Thanks for the input. My wiring is in fairly good condition considering the age, however anything is possible.

For the record, I'm very familiar with troubleshooting, I work as an electro-mechanical Engineer and have an aircraft mechanic/technician A&P license. With that said I have worked on cars, trucks and aircraft for over 25 years.

well thats more than ive been alive so i trust you

i only say those things because my wiring that would go to a fuel tank valve, reverse switch, seatbelt switch, and other fun accessories like fuel gauge etc all run under my cab, taped together, and the cab has definitely severed some wires with sharp rusty bits at places. I can see an orange wire of some kind by the left foot area dangle partially under the truck. I assume thats fuel gauge but who knows. My reverse lights DO work magically, but honestly i wouldnt feel confident betting on that staying constant in bad weather let alone time lol

 

[Conejo_K10]

Having loose dangling wires would make me nervous. I would suggest securing them with automotive tubing or something similar. GM used to use cloth tape to protect interior wiring.
I'm particular when wiring, routing away from sharps or hot surfaces.

Fortunately I added an auxiliary flood light to the back of my truck, so I can use it until the b/up lights are working. Yes, this is a separate circuit.

 

[AuroraGirl]

Having loose dangling wires would make me nervous. I would suggest securing them with automotive tubing or something similar. GM used to use cloth tape to protect interior wiring.
I'm particular when wiring, routing away from sharps or hot surfaces.

Fortunately I added an auxiliary flood light to the back of my truck, so I can use it until the b/up lights are working. Yes, this is a separate circuit.

oh that is funny, because I have a headache rack which my grandpa... oh lorde.. wired a complete set of running lights down the sides like a trailer with side markers , no harm in that on its own, right?

wirenuts, tape, bullet connectors, , more tape, and just a mess of routing.

I dont know WHAT wiring is what, so much is inop, but i do know the switch to the very left on my instrument panel illuminated an auxillary backup light he had mounted in the back, and I used a LED fog type lamp I had originaly on my plow mount to put toward the rear since the truck has headlights now. the poor thing is only on property and i figured rear illumination on a small swivel would far outweigh additional forward lighting

believe me its not ideal. You should see my plow wiring... dear god.

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here you can see the LED on the 45 degree upward slope

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here i had it out front for snow plowing

 

[AuroraGirl]

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not to cause crippling depression with your background, but see that clamp in the back? thats the positive hookup.

the worm clamps on the pump? thats grounding a wire that when not grounded doesnt allow my switch, which is a bush button shoved through the dash with tape

 

[Astar350]

Just replaced mine… buy a cheap 7/8 socket 3/8 drive… slide your new back up switch inside socket, mark it and cut it down to size. I also purchased a slim profile ratchet from harbor freight.
Came right out…….