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5/08/2017 6:21 PM  #1

Under dash Courtesy Light Wiring

1966 Mustang Coupe, 1988 5.0 Swap, T5z

​I'm trying to identify 13A709 in this image.  I previously had the underdash courtesy light installed and functioning in my car but after ripping out the older harness I realize they were just spliced in some how.  The painless harness (20120) has provisions for the door lights, the rear post courtesy lights for a fast back, and console lights.  I'm trying to figure out how the underdash courtesy lights connect and whether or not there is a dedicated additional connector wire I can purchase.  This old diagram references 13A709 but the few hits on that number point to the fastback pillar connecting wires.   thank you


5/08/2017 8:09 PM  #2

Re: Under dash Courtesy Light Wiring

The stock harness took an "always hot" wire and ran it to both door switches.  The other side of the door switches went to all the courtesy lights.  Any time any door switch closed, all the lights got B+ and came on since they all are grounded at their respective sockets. 

I have no clue what painless did but you say they provide provisions for all the lights...I would guess that these wires go to each bulb and that they are spliced together someplace with a couple of wires that go to each door switch and the courtesy switch on the HL switch.  There should also be an always hot wire that goes to both door switches.  This likely comes from the HL switch since it's always hot. I seem to recall that is how Ford did it...The hot leg came from the HL switch and went to both door switches.  The switched leg went from the HL switch, to both door switches and to all bulbs.

Probably added more confusion than help but I hope not. 

I just whupped up a quickie drawing.  Pm me with your email addy if you want it.


The real question you mind NOT being a Mustor?

5/08/2017 8:18 PM  #3

Re: Under dash Courtesy Light Wiring

Like BB says, all the "Courtesy" lights; underdash, door or 2+2 sail panel lights run off the same circuit so you should be able to splice those underdash lights in with either of the painless courtesy circuits. Check the original skeezmo at the link:


5/09/2017 8:05 AM  #4

Re: Under dash Courtesy Light Wiring

OK, I think I see the confusion after looking at the schematics.  Apparently there are 2 sets of "courtesy" lights.  There are the under dash (which is what I'm trying to install) and the console lights which obviously require you to have a console (I do not).  I believe I can leave the console lights unused at the moment and just splice into the door switch light wire on one side or both sides and it should work as intended.  Door open > switch activated > door, dome, and under dash lights come on.

     Thread Starter

Board footera

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