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Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

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post #1 of (permalink) Old 09-19-2005, 11:37 AM Thread Starter
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Fiat lux (et facta est lux)

Did you know that there were 2 light switches for CJ's? To bad quad and 4WD only sells one.

Because of this I've been doing a little more investigation into this Lighting stuff.

THe basic problem is the way that the light switches connect to the fuse box.
There are actually 3 fuses involved with this switch.

Early CJ light switches hook up this way: 76-77 for example.

Notice the orange wire. This connects to a plug....Someplace, probably the harnes for the courtesy lights. In this case power for this connection has to come from the main headlight source. That is why there is a jumper on these switches.

Here an 82 CJ light plug:

On the 82 CJ, This wire is now White wire comes from the fuse box were there is a fuse supplying power for the parking lights. (and panel lights)

Here is a closeup of an 82 fuse box schematic

You can see what fuses are involved.

But before you go blind tracing out the runs. I put together a collage of prints and show how the wires run in an 82 and later light circuit. Not all lights are covered.

White wires do not come out wery well so I made the white wires blue.
As you can see there are 3 fuses involved.
1 20 Amp fuse for the tail lights and parking lights
1 15 amp fuse for the Dome-Courtesy lights
1 3 amp fuse for the dash lights.

Make sure you inspect all 3 fuses when troubleshooting lighting problems.

Basically power from a fusable link connected to the battery connects the the 15 and 20 amp fuses and then to the light switch. This is the main source of power to the head lights.

Power for the parking lights travel thru the 20 amp fuse to the switch. Inside the switch is a jumper that connects this circuit to the wiper for dimming the panel lights. This jumper is indicated with the dotted yellow line in the picture.
When the switch is in the Park or headlight position the power then goes thru the switch out to the tail lights and parking lamps. obviously if this fuse is blown then you would not have BOTH parking lights or Panel lights. If you did out in an old style switch with the extra jumper it would then start working even though the fuse if blown.

The power also travels thru the wiper on the dimmer back to the fuse box thru the 3 amp fuse. and then to the panel lights . Pretty convoluted huh.

It even more interesting that the dome or coutesy lights get it power, in this case, directly from the 15 amp fuse in the fuse box. THe power then travels thru the dome light back to the light switch were it is GROUNDED by the light switch. This leads us to make sure the light switch is properly grounded also or your dome light won't turn on with the light switch.

Ever wonder what is inside?

Picture tells the story. Notice the circuit breaker for the headlights and the grounding tab for the dome lights.

Here is what the knob plugs into:

Notice the "V" shapped opening? This is what moves when you press the little button to release the shaft. Notice also the two sets of contacts.

Here is how they work:

One last thing, here is the back of the fuse box if you ever have to pull it out to check your lights.

It could be worse, It could be Lucas....
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post #2 of (permalink) Old 09-19-2005, 12:31 PM
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Re: Fiat lux (et facta est lux)

Thanks for the great 'class'... complete w/ color pics and understandable explanation.

Appreciate your taking the time and interest to do the 'investigation'..., then writing it up and sharing w/ the rest of us.
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post #3 of (permalink) Old 09-19-2005, 01:52 PM
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Re: Fiat lux (et facta est lux)

Great writeup John...

FYI...I have the harness for my jeep (84) out right now and nothing is in the way....let me know if you need any pics of hard to reach areas or something traced out.

I'm chasing down unused wires for my SBC TBI hookup. So far, I have been removing more than I'm putting back.
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post #4 of (permalink) Old 09-19-2005, 01:55 PM
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Re: Fiat lux (et facta est lux)

As usual...

[img]/ubbthreads/images/graemlins/goodpost.gif[/img] [img]/ubbthreads/images/graemlins/thumbsup.gif[/img] [img]/ubbthreads/images/graemlins/thumbsup.gif[/img]
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post #5 of (permalink) Old 09-19-2005, 03:59 PM
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Re: Fiat lux (et facta est lux)

What LEVE said! Good job!
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