Mustang Headlight to Firewall Wiring Harness (1966) Installation Instructions
This Headlight to Firewall Wiring Harness will fit 1966 Mustangs.
After nearly 50 years, the original headlight to firewall wiring in your 1966 Mustang can be frayed, cut or just completely destroyed by this point, especially if it was exposed to the elements at any point. Therefore, CJ's offers this handy headlight to firewall wiring kit for 1966 Mustangs so you can completely replace it with brand new, high quality wiring that will work every time!
Tools Required:
- Phillips Head Screw Driver
- Flat Head Screw Driver
- String
Install Difficulty:
- Moderate Project
1. To start the installation of your new Mustang headlight to firewall wiring harness, disconnect the battery. Connect the harness to the firewall plug in. When disconnecting the previous harness, make sure to pull from both the firewall plug and the old harness so you don't damage the firewall plug
2. Run the wiring harness along the driver's side firewall and attach it to the firewall using wire clips. To attach using the old ones, use a flathead screwdriver to separate the round grommet end from the male end. To reattach the clip, press the female grommet end over the male end and press down using a flat head screw driver.
3. Attach the plug to the regulator by pressing in also attach the ground wire to the screw holding the regulator in place.
4. Feed the driver's side headlight plug through the opening in the firewall; you will need to take off the cover and retaining ring for the Mustang headlights. There are four screws (Phillips) holding the headlight cover and three Phillips screws holding the headlight retaining ring. Plug in the driver's side headlight and reassemble the headlight retaining ring and cover.
5. Feed the driver's side horn plug through and plug in the Mustang horn.
6. Run the passenger side Mustang headlight wiring along frame above radiator. There are two more wire retaining clips along the way. Plug in passenger side horn wire and attach the ground wire to front firewall. Feed the passenger side headlamp plug through grommet hole just to the right side of battery and plug in head lamp following steps from step 4
7. The starting solenoid wire runs through the opening near the lower driver’s side base of the Mustang radiator and comes out on the passenger side. It is easier if you pull the new wire through by attaching it to the old section of the wiring harness, or if you have a somewhat stiff wire, like a coat hanger or picture frame hanging wire that you can feed through to help pull the wiring harness through.
8. Secure the wiring harness to the passenger side firewall with the retaining clips and connect end of wiring harness to the solenoid and the wire attaching to the Mustang alternator.
9. Make sure all of the wire retaining clips along the way are secure, then reattach the battery to finish up the installation of your new Mustang headlight to firewall wiring harness.
