Regarding 79 K5 Dome light Wiring

[ladybugblazer]

Alright guys I got the time today to rummage through the nest of wires under the abyss under my dashboard and managed to find some stuff and take some pictures. I looked near the courtesy lamp that I removed the lightbulb from and sure enough I found a white wire (1) and orange wire (#2). They were both tightly wrapped in electrical tape all the way through so I used my fingers to navigate. After around the instrument cluster I lost track of them because I was on my back on the floor with just my head inserted under and there was a lot on the way. Maybe if I can somehow remove the front plate of my dashboard I can have more access to see? Either way I found two things though of potential concern.

Finding #1 (see first Image)

I found an unplugged connector with an orange, white, and dark green wire (green circle). At first I thought this has to be it, but after further investigation I saw that it was coming from some black/silverbox with a jumble of different wires connected to it. I also saw a nearby place that it could potentially connect to (red arrow) but this is right under the instrument cluster under the steering wheel and its all cluttered and hard to access.

Finding #2 (see second image)

I traced the white ground wire from the door (blue arrow) and right on the other side found that it gets spliced into another white wire (right of the blue arrow). Now, that other white wire runs up and over the steering wheel and behind the instrument panel where I can't see, but I feel like it might be that same white wire that I traced from the courtesy bulb. Also, after the splice this new white wire runs under the carpet of the car along with an orange wire that you can see is coming from the fuse box. Maybe from here on they run under and then eventually up to the dome light? Not sure.

 

[Wes Harden]

The purple circle is the splice for the 3 ground wires in the circuit. the signal heading to the rear should travel up the "B" pillar driver side to dome lamp.
orange wire green arrow has obviously has been modified at fuse panel. Not convinced it is a dome lamp circuit wire. What about the orange wire in the just to the right in the picture? Where does it go ? If you had not said the white orange wires go to that black and silver box I would have said it is the wiper delay module, now I am not sure.


White arrow provides ground to head lamp switch for dome lamp, ohm check that wire to ground. The orange arrow is hot at all times and is the power to the lamps. The orange wire at switch is powered from the fuse panel. The other orange wire in that cavity powers the under dash bulb, then on to the overhead dome lamps. There is no cargo lamp switch in your blazer, I see one in the diagram but I am thinking is for pu trucks bed lamp on cab.

 

[Wes Harden]

The green circle connector possibly goes to brake switch, which would make the black and silver box the cruise control module

 

[ladybugblazer]

Alright Wes I managed to take a look at it again and find some more things of interest. By the way just to clarify the white/orange wires do not go to the black silver box. A bunch of random green and black wires go to it, but the random unplugged connector with a white/orange wire come out of the silver box. Also the car does have cruise control so this could be the module. I checked white arrow to ground and it checked out and had some 20 ohms or something like that. The other orange wire that you were concerned about just to the right of the picture is a orange/black striped wire and seems to go to the instrument panel. Now that being said, let me talk about what I found with the 3 ground wire splice:

I took off all the crust old tape that was probably from the 70s and found this old solder. I tested the solder to ground for ohms and got a reading on it so it seems to check out.
I went further down the path of the white/orange wire up to the B pillar:

The wires seemed to run parallel/under this door sill plate.

Around the back seats just before it started to go up the pillar here's what it looked like. The orange/white wire along with bundles of clear speaker wires...

Up at the B pillar this connector was here with the orange/white wire. I tested orange for ohms and it checked out and had a reading. I checked white for ohms and it had nothing on either side of the connector. I decided their must be an issue with the white wire between here and where it runs under the door sill...

I decided to unscrew the door sill and look under. I found an abundance of the clear speaker wires along with the orange/white wire covered under duct tape...

Directly under the door sill I found the orange/white wire wrapped in an obscene amount of black tape. I decided this is worth investigating and began removing tape. They used alot of it.

Gas can for reference


Under the tape here's what I found. I found the orange/white wire both with crimp connectors on the ends. the orange wire as you can see is a little bit fraying on the right side after the connector. I lightly tugged on the orange wire and the left end fell out easily. I tugged tightly on the white wire and it seemed very secure I pulled hard but it wouldn't come out. I put the orange wire back in the connector and tested for ohms. I got a reading on the orange wires some how even though it was so loose. I decided to test the white wires for ohms on either side. On the side coming from the nasty splice I had to really shove in my multimeter probe and sure enough I got a reading. On the side towards the b-pillar no matter how hard I shoved the probe I could not get a reading. I guess the play is to redo this connection (both rather for the orange one too)? Question is how do I undo this crimp

 

[Wes Harden]

My preference would be to cut them out. Solder and heat shrink them. Not knowing your tool options. Here are a couple more options, https://www.amazon.com/dp/B0CCSM9FB1?psc=1&ref=ppx_yo2ov_dt_b_product_details these work well. Strip the wire @ 1/4" ea side, slid into the heat shrink, so bare copper from both side is in the silver ring, and heat. A small heat gun is preferable but a lighter or propane torch can be carefully used. Last option would be the same type butt connectors, both should be the red(small ga) color. Good crimping tool is essential with these type connectors.

 

[Wes Harden]

Oh and good job I think you found it. I am sure the bad crimp on the orange wire would show voltage on a meter but would not power a load light the 2 dome lamps

 

[ladybugblazer]

Alrighty I went ahead and took apart the old butt connectors and replaced them with new ones of the proper size. I pulled on each one after I finished and a couple failed the pull test so I crimped them in again and made sure they were secure. Afterwards, I tested continuity for each orange/white wire at each dome light. The white wires had good continuity, but the oranges did not and had very high ohm readings. I remembered taking the courtesy light out maybe did that so I put it back in and tested again. Sure enough now the oranges had continuity to both the whites and ground for both dome lights. I then heated the heatshrink on my butt connectors and put my door sill plate back. I also wrapped electric tape on the factory white wire splice. Tested orange/white again and they still checkout out for continuity


I want to start connecting the middle dome light together like how it was before except with good replacement pigtails I bought

Still not exactly sure what wire #3 is should I splice off #2 into #3 and connect them together like it was setup before? Thanks for helping me out with all this

 

[Wes Harden]

3 is not factory. Previous owner added something that needed to hot at all times.
Is there another charge port or cargo lamp in the rear?
Even though the dome circuit is on a 20 amp fuse I am not how wise adding more load at that spot would be.
Need to figure out what it is for before I would consider reconnecting red wire #3.

 

[ladybugblazer]

It seems to be running under the headliner but I don't see it coming out from under the dash or on the sides from either passenger or driver side. I feel like it might run as i drew in magenta below to the overhead console:

I don't think overhead consoles were an option for these that has to be custom right?

Its got 3 lights in it as well but I don't see the red wire in this unit. Maybe PO spliced under the headliner so it can split for the 3 lights?

Also, while I was under the dash on the passenger side where my A/C is I found this little thing with a knob on it that has wires and tubing connected to it:

What might that be?

 

[Wes Harden]

Ok I believe the red wire would indeed power the add on front console. The lights in that unit wouldn't tax the circuit enough to be a problem.
So splicing the red wire to the orange wire is ok .
That is an ac temperature adjustment. The capillary tube senses the out let/ or suction side of the evaporator. This along with other controls determines how long the compressor is on or off.
Does your k5 have aftermarket ac?

 

[ladybugblazer]

I believe it is aftermarket

 

[Holey76 - Square Nut]

Thank you guys this is all good information. Wes, should the battery be disconnected before testing the wires for voltage/ohm? Also what values should I be getting for this two procedures?

Thanks

If you have a V.O.M. check the wries "hot". (I would suggest a schematic to better understand each wires function) but one wire should be 12 volts all the time. Another switched and the 3rd should read zero voltage.
One the zero voltage wire, switch your vom to ohms, and check continuity to ground, when the doors opens and closes. Ohms should go from nearly zero to infinite as door opens and closes.

 

[ladybugblazer]

The wires up at the top are running short to the harness to where I can't crimp. I'll solder them later this week and heat shrink em

 

[ladybugblazer]

All lights operational and bright thank you all!