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OPR Classic Update Wiring Kit (87-89 5.0L)

AmericanMuscle no longer carries the OPR Classic Update Wiring Kit (87-89 5.0L). Please check out 1979-1993 Foxbody Mustang Miscellaneous Restoration Parts for an updated selection.

Features & Details

  • Updated Wiring Kit - Ideal for Modified or Project Mustangs
  • Works with Aftermarket Gauge Packages Only
  • Not Intended as an OEM Replacement
  • Made in the USA
  • Fits 1987-1989 EFI 5.0L V8 Mustangs
Updated Harness Kit. If you have been modifying your classic 1987-1989 Foxbody Mustang with modern amenities you may need to upgrade your old factory wiring harnesses. This Classic Update Wiring Kit is ideal for modified and project Mustangs. It features a compact fuse box with aluminum mounting plate that can be used for both early and late model mounting locations and includes a 175 amp Mega Fuse for main system protection.

Dash Wiring Kit. The Dash harness comes with all factory steering column connectors installed and is ready to plug into your Mustangs factory switches. New headlight and hazard switch connectors come pre-installed on harness. Wiring with new terminals for fog lights or rear defrost switches are included in the dash harness. New door switches and connectors for courtesy lighting are also included.

Instrument Cluster Wiring Kit. The Instrument Cluster wiring is designed with a “cluster harness disconnect” system for easy service and assembly. Supports most aftermarket gauge packages. This Kit is

not designed to connect to the factory gauge cluster.

Front Light Wiring Kit. The Front lighting harness includes extra long leads that can be routed for stock or custom appearances. New headlamp, directional, and marker lamp sockets come installed on the front light kit. Includes new windshield washer pump connector,  electric fan relay trigger and brake fluid level wiring.

Rear Body Wiring Kit. Rear body harness comes complete with tail light, third brake light, turn signal, reverse lights, license plate lights and running light connections. As well as hatch, fuel pump and rear defroster connections.

Engine Wiring Kit. Engine wiring includes feeds for coil, tach, water temperature, oil pressure, electric choke, and electric speedometer (if needed). A heavy gauge alternator feed and fusible link are also included for any typical high output 1 wire or internally regulated alternator.

Application. This Classic Update Wiring Kit is specifically designed to fit modified 1987-1989 GT and LX Mustangs equipped with the 5.0L V8 engine.

Not intended as an OEM replacement.

Technical Notes.
  • This Wiring Kit should be used for modified applications only, it is

    not intended as an OEM replacement.
  • The fuel pump relay and inertia switch are

    not included.
  • This Kit supports the use of aftermarket and stand alone type fuel injection systems. It is

    not intended to interface with the factory ECU or other body control modules.
  • This Kit supports the use of a high current self-exciting 1-wire alternator or other style internally regulated alternators. An adapter may be necessary in some applications.
  • This Kit is

    not designed to connect to the factory gauge cluster. The Kit is configured to work with aftermarket gauge packages only.
This Wiring Kit does

not include the following connectors from your original harness, as they are obsolete and are no longer available. You will need to remove the following, which are illustrated for visual identification on pages 4 and 17, of the instruction packet:

  • From the dash harness:
    • A/C mode selector switch connector (New terminals are on kit harness)
    • A/C illumination lamp connector (New terminals are on kit harness)
    • Blower motor connector (New terminals are on kit harness)
    • Wiper motor connectors (x2) (New terminals are on kit harness)
    • Wiper module connector with 5” section of wires
    • Fog light switch connector (New terminals are on kit harness)
    • Defrost switch connector (New terminals are on kit harness)
    • Defrost module connector (New terminals are supplied loose piece in the kit for this connector)
    • Interior light dimmer rheostat connector (New terminals are on kit harness)
    • Firewall grommets (x2)

  • From the rear body harness:
    • Corner parking lamp socket; uses 194 bulb


Fitment: Details

CA Residents: WARNING: Cancer and Reproductive Harm -

What's in the Box
  • (1) Mega Fuse Kit
  • (1) Practice Terminal Crimping Set
  • (1) Dash Harness Kit
  • (1) Instrument Cluster wiring kit
  • (1) Front Light Wiring kit
  • (1) Rear Body Wiring kit
  • (1) Engine Wiring Kit
  • (1) Fuse, Relay, and Flasher Kit
  • (1) Kit Introduction Instruction Sheet
  • (1) Warning Sheet
Installation Info
Tech Specs
Will it fit my Mustang?

    Customer Photos

      Questions & Answers (1)

      1 Top Rated Question

      I bought this harness I know its not intended for factory oem replacement but is it possible to hook this up to factory ECU and Harness to get it to work. I would hate to half to buy a stand alone system just to get a dash harness to work. I know the factory gauges will not work thats why Im buying a Dakota Digital setup. The Directions are vague as far as ECU hook up and kind of confused. Switched everything else over from old harness that needs to be switched. Let me know if you have any Insite and if anyone has installed this kit using factory ECM at least. A stand alone system is very expensive already have 1700 in cluster and Dash harness. So getting expensive.

      Post Your Question

        Customer Reviews (3) Write a Review

        Overall Rating 4.7

        out of 5 stars

        • 5/5

          June 27, 2017

          5.0 harness

          Great detailed harness, extremely happy ! The kit was amazing.


          Year: 1994 Submodel: Cobra

          Helpful (12)

        • 5/5

          November 06, 2016


          I haven't installed this yet. But am already very pleased with the quality. It appears to be well thought and and the instructions are large, descriptive and in color


          Year: 1990 Submodel: Other

          Helpful (13)

        • 4/5

          March 29, 2016

          Great replacement, kind of pricy but well worth it

          This wiring kit helped me with replacing out burnt wires that got damaged from a shortage that happened with some fuses. Everything seems to work just right so far just like i would hope thanks AM


          Year: 1987 Submodel: Other

          Helpful (14)

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