1965–1966 Mustang Wiring Harness
The mid-’60s Mustang set the standard for American performance—and with a Painless Performance Direct-Fit Chassis Harness, it can finally have the reliability to match its legend. Designed for factory-style installation, this 22-circuit harness includes most of the original Ford connectors pre-installed and every wire color-coded to Ford standards with printed circuit IDs for easy identification.
Engineered to support both carbureted and EFI conversions, the Painless 20120 harness uses modern fuses, relays, and labeled circuits to simplify every part of your Mustang’s electrical system. From a weekend cruiser to a concours restoration or full restomod build, this harness delivers OEM fitment with upgraded protection, organization, and expandability.
Why Choose Painless for Your Mustang Build
Designed specifically for 1965–1966 Ford Mustangs
Factory Ford color-coded and printed wires for easy troubleshooting
Includes horn and accessory relays, mini blade fuses, and maxi fuse protection
Pre-terminated factory-style connectors for plug-and-play installation
Compatible with carbureted or standalone EFI engines
Divided into logical sections for clean routing and serviceability
Built-in fan relay activation power and extra accessory circuits
Lifetime warranty and U.S.-based tech support from Painless Performance
The Painless 22-Circuit Direct-Fit Harness gives your classic Mustang a modern electrical foundation while maintaining factory-style fit and finish. With 12 fuses, horn and accessory relays, and every wire printed and color-coded, this harness eliminates guesswork and ensures professional-grade results. Each kit includes factory-style connectors for ignition, headlight, wiper, dimmer, and brake switches, along with labeled circuits for quick setup.
Key Features
22 total circuits / 12 fuses with horn and accessory relays
Factory-fit design for 1965–1966 Ford Mustangs
Pre-installed connectors for plug-and-play simplicity
Ford color-coded and printed wiring every 12 inches
Modern mini blade and maxi fuse protection
Includes A/C power wiring, fan relay activation, and radio circuits
Works with carbureted or EFI powertrains
Clean, OEM-style routing through factory grommet firewall passthrough
Includes Circuits For
A/C & Heat, Accessory / Cigarette Lighter, Accessory Relay, Backup Lights, Brake Lights, Charging, Courtesy & Dome Lights, Electric Choke, Emergency Flashers, Fan Relay Activation Power, Fused Power Source, Glove Box Light, Headlights, Horn (Relay), Ignition Coil, Instrument Panel Lighting & Gauges* (Ammeter, Fuel, Oil, Tachometer, Temperature, Voltmeter), Park Lights, Radio/Clock (Constant & Switched), Starting, Tail & License Plate Lights, Turn Signals, Wipers, and Washer Pump.
Perfect For
Owners wiring a 1965 or 1966 Ford Mustang who want a factory-correct installation with modern protection and expandability. Ideal for restorations, street cars, and Pro Touring builds—this Painless harness blends OEM appearance with upgraded safety, simplified service, and unmatched reliability.