How to Install LED Fog Lights on a Classic Mustang

How to Install LED Fog Lights on a Classic Mustang

Last Updated January 17, 2024 | Bill Tumas

Your classic Mustang's headlights are vital for safety, but even with replacement LEDs, driving down foggy roads can still be problematic. Performing a fog light installation on your 1965-1973 Mustang will help improve visibility even in the haziest weather conditions. Fog lights also give a custom, stylized look to your Mustang's front end, making it a popular upgrade among enthusiasts.

This Mustang fog light installation will require some modification and rewiring, but don't panic. Our step-by-step instructions will walk you through everything you need to know to add new fog lights to your classic Mustang. With the right tools and knowledge from this guide, you should be back on the road in three hours or less.

Classic Mustang Fog Light Wiring and Install Instructions

For our classic, we chose the 1965 Mustang GT Fog Light Grille Kit.

Your fog lights might be different from the ones we chose, but the installation and how to wire your fog light kit should be similar for all 1964.5-1973 Mustangs.

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Parts and Tools Needed:

  • ⅜” Ratchet
  • ½” Shallow Socket
  • 14 mm Shallow Socket
  • ½” Deep Socket
  • 14 mm Deep Socket
  • ¼” Ratchet
  • 8 mm Socket
  • ⅜” Deep Socket
  • 6” Extension
  • 14 mm Wrench
  • Phillips Head Screwdriver
  • Pick
  • Bezel Tool
  • Small Flat Blade Screwdriver
  • Wire Crimpers
  • Wire Cutters
  • Wire Strippers
  • Razor Blade
  • Angle Drill
  • Standard Drill
  • ½” Drill Bit
  • 5/16” Drill Bit
  • ⅛” Drill Bit
  • Tape Measure
  • Marker
  • Flashlight
  • Safety Glasses

Step 1: Remove Front Bar with Horse and Corral

On either side of the bar, remove the two screws holding the bar in place. Next remove the two screws at the top of the Corral with a Phillips-head screwdriver.

Mechanic removing the corral bar on a classic Mustang

Step 2: Remove Grille

Remove the top and bottom screws from the grille. Next, remove the two bolts on either side. Once the bolts are removed, lift up on the grille to pull it out.

Mechanic removing the grille on a classic Mustang

Step 3: Detach Non-GT Grille Bars

Remove the two bolts holding the grille bars to the corral. Set these parts aside for later use.

Mechanic removing the grille bars on a classic Mustang

Step 4: Install Bulbs Into the Fog Light Housing

Unscrew the two screws that hold the front of the housing in place. Next, pull the wires through to connect them to the bulb. Connect the wire at the attachment point and tighten down the screws to secure the connection.

Slide the grooves in the side of the light into the indentations in the housing. Reinstall the front cover and tighten the screws down to secure it.

Repeat this process with the other bulb.

Mechanic installing fog light bulbs a classic Mustang

Step 5: Attach New Fog Light Bars

Grab your old horse and corral and slide the fog light bars into the sides of the assembly. Tighten down the bolts with a socket wrench to secure the new bars.

Mechanic attaching new fog light bars a classic Mustang

Step 6: Disconnect the Battery

As with any electrical install, make sure you disconnect the battery before continuing.

Mechanic disconnecting the battery on a classic Mustang

Step 7: Drill Wiring Support Holes

From the side of the fender, measure 7 ¼” towards the radiator and 1 ¼” down to find a frame location to drill your wiring support hole.

Start by drilling a small pilot hole, then open it up with a larger drill bit. Repeat this process on the other side.

Mechanic drilling wiring support holes on a classic Mustang

Pro Tip: If your horn wiring is in the location where your fog light wiring should be on the passenger's side, you may have to drill in a nearby location.

Step 8: Install New Grille

Slide the new grille into the same location the old one was removed from. Tighten down the two side screws as well as the top and bottom ones to secure it. Reinsert the factory U-nuts.

Mechanic installing a new grille on a classic Mustang

Step 9: Install Grille Horse Support

Place the grille horse support on top of your new grille. Tighten down the two bolts on either side. Next, side in the central screws with washers and tighten them down. You may need to readjust the grille so the screws fit.

Mechanic installing the grille horse support on a classic Mustang

Step 10: Install New Horse and Corral with Bars

Install the connecting bolt at the bottom of the corral bar. Turn it a few times so it sticks out slightly.

Line the bars up with the lower and upper connection points on the grille. Insert the two screws at the top connection point, then tighten the bottom bolt.

Finish installing the fog light bars by mounting the sides to the grille with the provided bolts. You may need to readjust the positioning to line up the holes with the grille.

Mechanic installing new horse and corral bars on a classic Mustang

Step 11: Attach Fog Lights to Fog Light Bar

Fish the wires for the fog light through a hole in the grille. Next, install the washer and nut to the base of the light housing. Tighten down the nut with a ratchet. Fish the wires through the hole you drilled in the firewall in Step 7.

Mechanic attaching fog lights to the fog light bar on a classic Mustang

Step 12: Ground the Wiring

Locate the black ground harness wire, and find a place to ground the wire. In this case, we'll be using the bolt holding the radiator to the radiator support.

Unscrew the bolt enough to attach the grounding ring. Once the ring is attached, connect the ground harness wire to the fog light wiring assembly.

Mechanic grounding the fog light wiring on a classic Mustang

Pro Tip: You may need to cut off the edge of the grounding ring to create a spade connector if the bolt you are grounding the wire to is too large.

Step 13: Attach Passenger's Side Power Wire

Locate the passenger's side power wire lead. The passenger's side lead will have a single wire connected to a female end, while the driver's side wire will have two wire leads.

Take the passenger's side wire and follow the headlight wiring across the firewall. Attach it to the gray, male wire connector on the passenger's side fog light wiring harness.

Next attach the driver's side power wire and follow the headlight wiring on the driver's side until you reach the firewall at the front of the car.

Mechanic attaching passenger side fog light wiring on a classic Mustang

Step 14: Dill Wiring Hole In Firewall

In the interior of your Mustang, locate the hole for the headlight wiring below the dash. You'll need to drill a hole right below the headlight wiring harness for the fog lights.

Trim away some of the firewall insulation and drill a hole from the inside out.

Mechanic drilling a wiring hole in the firewall of a classic Mustang

Step 15: Plug in Male Feed From Fog Lights

Once the driver's side wire is fed to the back of the firewall, connect to the male feed from the lights and fish the entire assembly through the previously drilled hole.

Mechanic installing the male fog light feed on a classic Mustang

Step 16: Remove Instrument Cluster

Use a screwdriver to remove the two screws at the base of the instrument cluster. Pull the cluster towards you to remove it from the dash.

Mechanic removing the dash instrument cluster on a classic Mustang

Step 17: Locate Fog Light Wiring Connector

Once the instrument cluster is removed, follow the wires coming off the headlight switch down towards the fuse box. Look for a black wire with the same connector type as the fog light wires. Pull this wire down below the dash.

Mechanic locating the fog light wiring connector on a classic Mustang

Step 18: Connect Fog Light Wiring

Disconnect the wiring connector from the previous step and install the wiring harness in between the two connector ends.

Mechanic installing the fog light wiring connector on a classic Mustang

Pro Tip: To make sure you have the right wire, disconnect the two ends from each other, reconnect the battery, and turn your headlights on. If you have the right wire, your taillights will be off.

Step 19: Get Power for Circuit Breaker

Under the dash, locate the thick black and orange wire. Strip a section of the wire and use the wire tap supplied with your headlight kit to attach the headlight switch wire. Clamp the supplied connector with a pair of pliers to secure the connection.

Mechanic establishing the fog light wiring power connection on a classic Mustang

Step 20: Attach Circuit Breaker Wiring

Locate the circuit breaker from your fog light kit. Attach the thinner blue and black lead that you just connected to the under dash harness at the connection point on the breaker that says “battery.” The thicker wire will attach to the auxiliary connector.

Slide the leads onto the studs and secure them with the supplied nuts. Tighten the nuts down with a ratchet.

Mechanic attaching fog light circuit breaker wiring on a classic Mustang

Step 21: Mount Circuit Breaker

The best location to mount your circuit breaker is the screw attached to the wiper motor bracket. Loosen the screw with a screwdriver, attach the circuit breaker, and tighten down the screw.

Mechanic mounting the fog light circuit breaker on a classic Mustang

Pro Tip: Once the circuit breaker is installed, it's a good idea to plug in the fog light switch and reconnect the battery to test and make sure the lights come on. Remember to disconnect the battery again before you continue.

Step 22: Mount Fog Light Switch

The best place to mount the fog light switch is to the left of the instrument cluster, right on the curve of the dash. Start by drilling a small pilot hole at the location you would like to mount the switch, then open it up with a larger drill bit.

Insert the switch into the drilled hole from the inside of the dash. Make sure the “on” position is facing up. Install the bezel on the switch threads and tighten it down.

Lastly, install the edge of the switch by sliding it onto the rod and tightening it with a small screwdriver.

Mechanic mounting the fog light switch on a classic Mustang

Pro Tip: Don't forget to reinstall your instrument cluster, reconnect the battery, and hide your wiring before you complete the installation.

Tackle the Rest of Your Classic Mustang's Lighting Upgrades

A new 1965-1973 Mustang fog light installation will give you better visibility and safety, while adding some more style to the grille.

Check out more installs to finish upgrading your classic Mustang's lighting:

This article was researched, written, edited, and reviewed following the steps outlined in our editorial process. Learn more about CJ's editorial standards and guidelines.