Identify these two wires under the dash and help me hook up my cab lights

[Tx Firefighter]

Fellas,

I have three questions concerning the wiring on my truck...

1) I'm using an 87 model donor truck for the wiring. I've got it all swapped over to my early cab and am finishing up with the details. What are these two wires hanging under the fuse box ? They are black and white.




2) How did GM tap the cab light power wire into the electrical system ? I know there are many places to hook my cab lights up to the light wiring harness, but I want to do it exactly like GM would have done on a truck with factory cab lights.

3) My 87 donor harness has pulse wipers with the module, but my 85 model steering column didn't have delay wipers. The wiring all plugs in easy enough. What will I need to do to convert the 85 column to operate the pulse feature ? Is it just swapping the turn signal stalk or what ?

[joe231]

Ooooo!!
Sweet
then I can assume you are running TBI?
I'll go look at the crew and see if I have those black and white wires....

[joe231]

yes it has it....black and white are for the seat belt switch.

I dunno on the cab lights, is there plug in spot on your fuse panel that says something about running lights or the instrument lights? Just a guess

on the steering column, I believe you need the stalk and the switch inside the column for the delay to work properly

[Tx Firefighter]

Joe,

Thank you very much for your answers. I'll shorten and heat shrink those wires up out of sight since the seatbelt thing is not needed.

On the cab lights, I don't see any obvious marked slots on the fuse box for them to plug in to. I know I could just splice in somewhere but I want it OEM perfect.

I'll look at the wiper switch deal since I'm going to be placing and order from classic parts tonight anyway.

That's an affirmative on the TBI swap. I parted out an 87 short wide last week and took everything from the tanks, fuel system, complete wiring harness, cluster, everything to make a complete 87 mechanically out of my 78. I likes me some fuel injection.

As a side note, I'm usually an ashole, but I'll get sentimental and say that I'm real sorry to see you and the family move so far away. There's not enough good folks around here as it is without y'all leaving.
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[joe231]

Sweet!!

thanks Kevin, that means a lot coming from such an a-hole
It was nice to be able to meet you and I'll still consider you a friend even when I'm 4000+ miles away

[Tx Firefighter]

I don't act sentimental very often so enjoy it while you can. I'll likely be a jerk for another year or two before I say something nice like that again.

[joe231]

whoa man!
that's good, I was starting to wonder if you were gonna start sending me kitty-cat emails

[ray_mcavoy]

Originally Posted by Tx Firefighter

2) How did GM tap the cab light power wire into the electrical system ? I know there are many places to hook my cab lights up to the light wiring harness, but I want to do it exactly like GM would have done on a truck with factory cab lights.

Factory cab lights are wired to the headlight switch. It's the same circuit that feeds the parking & tail lights (labeled circuit #9 on the factory wiring diagrams). There are 2 terminals on the headlight switch corresponding to ckt#9. One is roughly in the middle of the plug and should have an existing brown wire feeding the parking/tail lights. The other is off to the side right next to a dark green wire. I think this other terminal is unused (empty slot on the plug) on trucks w/o cab lights. If that's the case, it should accept a Packard 56 series female terminal which may already be present on the end of your cab light wiring harness.

[Tx Firefighter]

Originally Posted by ray_mcavoy

Factory cab lights are wired to the headlight switch. It's the same circuit that feeds the parking & tail lights (labeled circuit #9 on the factory wiring diagrams). There are 2 terminals on the headlight switch corresponding to ckt#9. One is roughly in the middle of the plug and should have an existing brown wire feeding the parking/tail lights. The other is off to the side right next to a dark green wire. I think this other terminal is unused (empty slot on the plug) on trucks w/o cab lights. If that's the case, it should accept a Packard 56 series female terminal which may already be present on the end of your cab light wiring harness.

Now that is an answer. You did everything but install it for me. Thank you sir, you've helped me very much.
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[joe231]

The knowledge here is amazing!!
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