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Since 1952

Painless Wiring 20120 1964-1966 Mustang 22 Circuit Wiring Harness

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Includes wiring harnesses, all connectors, brackets, flashers, and zip ties.
Painless Wiring 20120 1964-1966 Mustang 22 Circuit Wiring Harness
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Painless Wiring 20120 1964-1966 Mustang 22 Circuit Wiring Harness

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Watch the videos below for step by step instructions on how to correctly and safely install your Painless Performance harness.



Q & A

What's in the Box

Painless Wiring is saving you big money with their $100 mail-in rebate! For a limited time only receive a $100 mail-in rebate when you purchase any Painless Wiring Performance Chassis Harness or Fuel Injection Harness. Don't wait, offer ends September 30th!

One thing to never forget - the wiring in your muscle car is forty years old and updating to modern and safe components is easy. Owners and restorers of 1964 to 1966 first generation Mustangs can take comfort in the fact that there is now an electrical system upgrade from Painless to completely rewire this classic car. These Painless wiring harnesses feature many pre-wired connections and are color coded to make installation a snap.

This 22 circuit direct fit 1965-1966 Mustang harness has many of the factory connectors already installed on the harness out of the box.  This harness uses our unique covered micro-fuse block.  Also featured is an auxiliary circuit with 20 amp relay for accessories such as fog lights, or an electric fuel pump. Each wire is custom printed with the circuit identification as well as using Ford color codes for easy installation.  NOTE: THIS WILL NOT FIT 1964 1/2 MUSTANGS

1964-1966 Mustang Wiring Instructions (PDF)

Note: Some firewall modifications required.


  1. This harness comes with a fully assembled 14-circuit micro fuse block complete with 12 modern blade-type ATO fuses and 2 relays.
  2. Each kit also has provisions for factory instrumentation options, including either an alternator light or amperage meter, engine monitoring lights or gauges, a single turn signal indicator or separate left and right indicators, and an ammeter induction connection or direct connection.
  3. Some firewall modifications required.
  4. Kit comes preterminated for the following switches and accessories: blower motor, wipers, ignition, headlight switches, voltage regulator, turn signals and flashers, lighter, brake switch, dimmer switch, brake warning light and headlight bulbs. Additional circuits include electric choke, cooling fan, digital radio memory, tach power, signal indicators, dash lights, and ignition ballast resistor.
  5. This three section wiring harness features pre-printed, color-coded, high-temperature TXL wire to make installation easy and super reliable:
    1. MAIN SECTION - Includes wiring for the car's instrumentation, radio, courtesy lights, tail lights, turn signals, brake lights, license plate light, backup lights and fuel gauge sending unit.
    2. FORWARD SECTION - Includes wiring for the headlights, turn signals, parking lights, generator/alternator, regulator and horns.
    3. ENGINE SECTION - Includes wiring for the starter, ignition, electric fan, heater fan, oil pressure sending unit and engine temperature sending unit.

Includes Circuits for:

  • A/C & Heat
  • Accessory / Cigarette lighter
  • Accessory Relay
  • Backup lights
  • Brake lights
  • Charging
  • Courtesy and Dome lights
  • Electric choke
  • Emergency flashers
  • Fan relay activation power
  • Fused power source
  • Glove box light
  • Headlights
  • Horn (Relay)
  • Ignition Coil
  • Instrument Panel lighting and gauges *
  • Park lights
  • Radio / Clock (Constant and Switched)
  • Starting
  • Tail Lights and license plate light
  • Turn signals
  • Wipers and Washer Pump

* Including wires for:

  • Ammeter
  • Fuel gauge
  • Oil gauge
  • Tachometer
  • Temperature gauge
  • Voltmeter


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Product Q&A

1 questions : 1 answers

1 answers

I want to install halogen headlights which uses a lot of voltage/amperage. will this painless kit be compatible for this hook up?

Craig J.
Missouri City,Texas
July 12, 2015

I want to install halogen headlights which uses a lot of voltage/amperage. will this painless kit be compatible for this hook up?


July 13, 2015
I would install auxillary relays and run a seperate power source for the headlight in that situation
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