Pull switch under dash? '72 c20 Custom LWB

[Aztec.A]

So my truck is an extra basic 3/4 ton LWB.

I'm redoing some of the wiring for the meantime to get it somewhat driveable and get it to pass inspection.

I found this pull knob under the dash and it's connected to a switch. There's t wires running to it and a bare terminal exposed.

Any ideas what this is for?

[Grumpy old man]

Previous owner installed a on /off switch for courtesy light . start tracking wires and find the source .

[Aztec.A]

GrumpyOldMan,

I out a light bulb in the socket and it works with the passenger door switch. The driver side isn't working to turn the light on and off.

I checked for voltage on the interior dome light and I get voltage on the orange wire. Unfortunately the frame of the bulb holder is brittle and broken.



I'm not picking up any readings on that mystery switch.

Here's some pics where it's connected. The switch doesn't turn the courtesy lights off.


Still stumped here. There is a wire that's cut on the courtesy light harness too.

[BluTrukker]

Originally Posted by Aztec.A

GrumpyOldMan,

I out a light bulb in the socket and it works with the passenger door switch. The driver side isn't working to turn the light on and off.

I checked for voltage on the interior dome light and I get voltage on the orange wire. Unfortunately the frame of the bulb holder is brittle and broken.



I'm not picking up any readings on that mystery switch.

Here's some pics where it's connected. The switch doesn't turn the courtesy lights off.


Still stumped here. There is a wire that's cut on the courtesy light harness too.

The flux capacitor?
Posted via Mobile Device

[Grumpy old man]

yeah , I would start tracking the wires from the pull switch it may just be for a set of after market fog lights ,it's not stock .

[Aztec.A]

LOL the flux capacitor, be pretty rad if it was Bluetrukker.

Grumpy Old Man, I'm gonna do my best to trace it tonight.

Unfortunately I don't have a wiring diagram for this truck. The wire leads it goes to is the main harness to the bulkhead and the ignition. It's spliced off the OEM harness.

I was hoping it was for the reverse lights since I belive the switch in the column is bad, but no matter what I don't have voltage on those lights.

All of my other lights work fine.

I do have a burnt out circuit board to the gauges I pulled out.

Maybe that was for the gauge lighting. Who knows, I figured I'd ask since the switch does look OEM from the outside.

Thanks dude.

[70STOVEBOLT]

What is Bluetrukker?

[LockDoc]

Originally Posted by 70STOVEBOLT

What is Bluetrukker?

A board member???? (see post #4)

LockDoc

[Andy4639]

I don't think it's a factory installed switch. It looks like a earlier type switch 66 back. The knob looks like it anyway. Is it a automatic are 3 speed? If it's a automatic then the backups come off the neutral safety switch on the column.

[70STOVEBOLT]

Originally Posted by LockDoc

A board member???? (see post #4)

LockDoc

Oh, duh! Didn't even see that. Boy do I feel stupid...

[dfwright]

My grandfather had one similar installed on our truck. It went to a light in the camper shell. They could be there for almost anything you could imagine.

[cleszkie]

Have you started the truck? Could be an ignition kill switch if the wires go to the ignition, as you mentioned above.

[Aztec.A]

Originally Posted by Andy4639

I don't think it's a factory installed switch. It looks like a earlier type switch 66 back. The knob looks like it anyway. Is it a automatic are 3 speed? If it's a automatic then the backups come off the neutral safety switch on the column.

It's a 3 on the tree.

Truck runs, definitely doesn't kill the ignition. It goes into the main harness towards the bulkhead and also splits to the ignition switch.

I did find power to it, but it does nothing. I have so much overspray underneath it it's hard to follow.

No wires go to the rear of the cab from that switch.

I'd definite doesn't turn off the courtesy lights, I got all of them to work off the doors now.

The reverse lights still don't work and the switch doesn't turn them on or off.

Hmmmmmrmmmmmmm

[Aztec.A]

Well I had a thread about this mystery switch under the dash. Grumpy old man (member name) was right about the switch being for auxiliary lighting. The switch had a massive stock pile of wiring plugged 2 ways from the battery to the switch and tee'd off to run power and ground to the rear of the truck where I found a hot wire dangling next to my newly installed rear tank!

I traced all the wiring and cut power to them from the battery immediately. Then I tore all the wiring and distribution blocks out. There was even live wiring under the dash and to the switch. The original owner before my friend had it did a crap job of wiring.

I assume there were driving lights up front and also some in the rear maybe to light up an area to connect/load a trailer. I've seen a switch like that before but I forget where.

You can see some of the gremlins I found lurking. Pretty sad to see the wiring was left live for decades. A fire waiting to happen.....

















I assume this is the horn relay?

[Grumpy old man]

Well... I'm glad you found that ! I've found some very creative wiring over the years and this was typical of some of the use any hot wire you can find specials . Spotting aftermarket switches is always a good indicator that someone has been into the stock harness and issues like this are why trucks burn to the ground .It's one more reason to check all the mechanical systems BEFORE attacking rust repair,paint or interior .One unfused short and you'll be checking out just how good that insurance policy you bought was . And tracking wires may be a PIA it's the only sure "fire" way to see what your really dealing with .

[New_70'C10]

Glad to see you solved the mystery and was able to clean up some of the wiring. I couldn't help but notice you've got that "special" yellow protective coating applied to everything under your dash; I've got that same type all over the inside of my ride as well.

[Aztec.A]

Grumpy Old Man, yes sir you took the words outta my mouth about a fire. Glad I took the time. What cost me 3 hours saved my truck. Now to tackle under the dash. There's some ugly gremlins in there too.

New '70C10 thanks man, yes it cleaned up the wiring big time. I take it whomever painted your truck was "lazy" and gave you "special" coating too! Lol. Man it's a real PITA scratching some away to see the colors of the wires. I'm resorting to cutting the original tape wrap and will rewrap it with friction tape.

I see you're in Edmond. If you're ever needing tint, paint protection film, vinyl wrap, custom interior or stereo go see my bro Joe Gonzales @ Superior Auto Sports. Tell him Dave from San Antonio sent you and he'll take care of you. I go up there a couple of times a year. Maybe sooner than later w my truck.