• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-

1966 Mustang Coupe Wiring

  • Thread starter Thread starter ReturnToHanger
  • Start date Start date Apr 3, 2020
  • Tags Tags
    1966 gt style fog lights wiring
R

ReturnToHanger

New Member
Feb 13, 2020
8
0
1
Alabama
Apr 3, 2020
#1
  • Apr 3, 2020
  • #1
So I’m wiring up factory style fog lights on my 1966 Mustang, and I’m at the part where I have to splice the blue/black wire of the fog light wiring harness into a power source. I’ve read that instead of splicing into the main harness, I could instead use the post at the back of the ignition switch.

I have an aftermarket radio that is also hooked up to the ignition post for the switched power for when the vehicle is running, and I’m also going to install a rally pac. I have read that I will also need to use this post for power for the rally pac.


So essentially, is the post a proper replacement power source for the lights, AND is it safe to run 3 wires off of the ignition post without blowing something?
 

wicked93gs

15 Year Member
Sep 30, 2006
1,198
228
93
Nashville TN
Apr 3, 2020
#2
  • Apr 3, 2020
  • #2
Factory vintage mustang wiring for lighting is...less than adequate, especially if said lighting is upgraded. First off, how do you want the fog lights to operate? On at all times ignition is on? When headlights are on only? To me, its never acceptable to run any wiring directly off the ignition switch...I will sometimes take a feed from the ignition switch to activate a relay through the 86 terminal, but the actual load will be drawn through the 87 terminal...its far better to burn out a fuse or a relay than it is to start a dash fire by overloading the poor factory wiring. Even stock the headlights work poorly because they are not run through a relay...just adding relays for headlights will vastly improve lighting.



This is how you should wire ANY high amperage accesory.
 
R

ReturnToHanger

New Member
Feb 13, 2020
8
0
1
Alabama
Apr 3, 2020
#3
  • Apr 3, 2020
  • #3
As they functioned from the factory is what I prefer. I never considered relays. Are they difficult to install? A lot of splicing?
 
You must log in or register to reply here.

Similar threads

C
Electrical HELP! 1989 5.0 Stick, Voltage Bleed onto Ignition Trigger wire
  • ChickenDeluxe
  • May 14, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
231
Fox 5.0 Mustang Tech May 24, 2026
ChickenDeluxe
C
A
1966 Mustang coupe / Brake lights and left rear turn signal not working.
  • ArizonaRob1966
  • Nov 3, 2025
  • Classic Mustang Specific Tech
Replies
2
Views
365
Classic Mustang Specific Tech Dec 24, 2025
Mcmahst
Electrical Ron Francis Headlight / Alternator Harness
  • dan50
  • Apr 30, 2026
  • Fox 5.0 Mustang Tech
Replies
0
Views
221
Fox 5.0 Mustang Tech Apr 30, 2026
dan50
1
Electrical Headlight harness trouble
  • 1985fox
  • Apr 14, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
254
Fox 5.0 Mustang Tech Apr 17, 2026
AeroCoupe
Electrical Alternator not charging after terminator 2 install.
  • Sfab79
  • Aug 24, 2025
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
40
Views
877
Fox 5.0 Mustang Tech Friday at 11:44 PM
Noobz347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?