Dome Light Wiring

[Scott2]

There are a few threads that touch on this in general. I have the 1979 Tech Manual and wiring diagrams but my ‘79 J10 has a few differences. It never had door jamb switches or courtesy lights, but it did have a dome light. I have no idea how it worked since the original dome light wires rotted out with the floor. There is a pair of brown/black wires cut and hanging down by the high beam switch, plus a single blue wire. Both are grungy on top but the colors show on the back.

I have a new dome light and the orange/white wires for that, plus I believe I have located a pair of jamb switches, but I have no idea how to wire this up w/o the courtesy lights. Anyone have the ability to sketch out a wiring diagram?

Thanks!

[letank]

my 74 does not have the door jamb switch. The dome light is turned on by the headlight switch on the dash, turn clockwise of CCW, can't remember which rotation, you pass the click of the dimmer and it closes the circuit to turn on the dome light.

Yes the wires run on the floor and are channel inside the B pillar where the seat belt anchor is.

[tgreese]

Same with my '77 J10 and '84 J20. The dome light is turned on by twisting the headlight knob - memory says CW to a click past full instrument lights brightness. No door jamb switches. I think this is typical of pickups; the door jamb switches are an upscale feature that is missing on base-level vehicles. On another truck I had, I added a toggle switch on the dash for the dome light, which is much more convenient.

Note that the wiring harnesses typically have extra connectors that may be left unused by the factory; this is a build-economy feature that reduces the number of different parts needed to add or delete options when the cars are built. Also means fewer service parts to stock after the cars are sold.

Suggest you print out the circuit diagrams oversize on paper and trace the circuits you need. Colored pencils work well for this. Unlikely anyone will have this circuit fully in memory and can draw it so you can skip the effort of tracing the diagram. In addition to the diagram proper, there is an alphabetic index that tells you what sector of the diagram each circuit is located. If you look at your truck, you may find the connectors where the door switches and courtesy lights would plug in on say a Wagoneer.

[Scott2]

Interesting - from previous searching I thought I needed the jamb switch. I should have power on through my system very soon. I may just connect the dome light to the black and brown wires by the dimmer switch and see if it works thru the light switch. I'll post how that goes.

Thanks!

[Mopar_guy]

On most all older dome light systems, the bulbs are fed constant 12v (orange wire) and the ground side (gray or white) wire is grounded thru the switches, either door jamb or headlight, to complete the circuit.