Topic: 66 wiring throwing me a curve.

[jamz66]

I have a 66, Dearborn, fastback with a warranty plate build date of 03A (January 3rd).  I am trying to re-wire my fog lights correctly but have run into a problem.  I have purchased all new fog wiring from NPD and know how/where to hook everything up except for the "splice" between the under dash harness and the tail lights.  The 66 NPD under dash fog harness uses the 3 wire/prong harness but my under dash harness and tail light harness only has a two wire/prong plug in.  How do I hook up my fog lights?  See photos below:

[midlife]

One of the mid-year changes in 1966 was the tail-light connectors: early had 2 pin plugs plus a separate bullet for the backup lamps.  Late had a 3 pin plug. 

As for your system, if you can plug the 2 pin tail into the 3 pin socket by keeping the wire colors good on either side, go for it.  The unused pin will go to the backup lamps on the tail.  If you can't plug it in, you'll have to cobble a pigtail from 3 pins to 2pins plus 1 using trailer connectors and wires.  Or contact me and I'll cobble you up something. 

[jamz66]

OK I was hoping I may be able to do that.  My one issue is if I remember (I'm not looking at car now) the black with red stripe back up light wire from the tail light harness is plugged into the yellow, triangular shaped plug behind the cluster.  Not sure what this is for.  Also, does anything get plugged into the third spot on the other end of the NPD harness where the two pin socket from the under dash harness is?

[midlife]

Backup lights on all 66's start by plugging into the 3 prong ACC fused female plug.  They then all go to the NSS/BU switch, and back to near the fuse box.  The early 66's then plug directly into the tail-light; the late then plug into a bullet near the fusebox on the underdash harness, which merely relays it to the 3 prong plug that now goes to the tail.
So...the remaining pin on the NPD pigtail mates with that black/red wire that is the output of the BU harness.

[jamz66]

Ok so my back up lights were removed in the past but all wiring appears to still be in place.  Looking at my wiring diagram I made of my under dash/tail light wiring I think my fog lights should plug in OK to the NPD harness as you mentioned and work.  Does the black with red stripe wiring for the back up lights look as if it is wired correctly (at least under the dash) so if I put back up lights back in they should work?

Thanks

Joey

[midlife]

I've no idea what the green wire with a female bullet is that's plugged into the 3 prong yellow plug, but that's neither here nor there.
Your wiring is essentially correct but I do not recommend wire nuts at all (they drive me nuts!! and they are not recommended for environments with vibration).  Why not take the line from (what your call the underdash harness but is actually the backup harness) and plug it into the NPD plug on one side?  You can plug the tail-light side into the other NPD plug. 

[jamz66]

Not sure why someone cut the wiring and put a wire nut there.  Are you saying to take the wire nut off and put the back up light harness end on the male plug of the NPD harness (right side in picture) and the tail light end in the female plug of the NPD harness (left side in picture)?

Thanks again!

[midlife]

Not sure why someone cut the wiring and put a wire nut there.  Are you saying to take the wire nut off and put the back up light harness end on the male plug of the NPD harness (right side in picture) and the tail light end in the female plug of the NPD harness (left side in picture)?

Thanks again!

OMG!  I thought the diagram was your proposed wiring, not what it actually was. 
Yes to your answer.  If the genders are wrong, then simply exchange positions on the NPD jumper/pigtail.  All that device does is to transfer the signal from one plug to the other.

[jamz66]

Got it!  Thanks for all your help!

Joey