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Early Bronco Painless Wiring Harness and Classic Instruments Gauge Cluster

Our Early Bronco gets wired

Verne SimonsAuthorTrenton McGeePhotography

Wiring harnesses, gauge clusters, switches, lights, relays, fuses, coil, alternator and more are all parts that make up any old 4x4s electrical system. And any old 4x4 that has undergone a full rebuild will need lots of attention paid to all of those parts and maybe more. Our Early Bronco Project is getting really close to being done. Most of the major components are in place and thus were down to setting up the finishing touches. One thing that our 1969 Early Bronco was lacking was wiring, gauges, switches, lights, and so on. Since this rig isn't a straight up restoration, but rather more of a resto-mod with an eye towards on- and off-road performance. That means that our Bronco will be running fuel injection, a modern ignition system, and a modern multi-speed automatic transmission with an electronic controller. That means multiple computers all of which need to be wired and mounted properly. We also opted to upgrade the rotten old analog gauges to a top-of-the-line LED illuminated Direct Fit Gauge Set for Early Bronco from Classic Instruments. This unit tells you speed, has a built in tachometer, voltmeter, temp gauge, fuel gauge, oil pressure gauge, turn indicators, high-beam indicator, and odometer. Wiring all this takes a special hand, and for that we leaned on our buddy Trent McGee, Freelance Writer, and head automotive wirier at Wicked Wiring in Glendale, Arizona.

Painless Performance Products 28 Circuit Direct Fit 1966-77 Bronco Harness

We started out by laying the new 28 Circuit Direct Fit 1966-77 Bronco Harness (PN 10114) in our bronco, and running the various groups of wires to their respective areas of the vehicle. Most of the wiring takes place under the dash so it's best to have the Bronco's dash removed. Ours was loose for repair and repainting anyways so we kept it aside until most of the wiring was in place. The Painless harness comes with all the wires you need to keep all the factory switches, lights, and general functionality. The kit came with the spade connectors to wire up each of the factory switches which we mainly sourced from Wild Horses 4x4. It would be nice if the kit came with factory style connectors for the headlight and ignition switch which are available as new parts. This kit is one of the most complete and pre terminated harnesses we've used, much nicer than making a universal harness fit a specific vehicle. We also like the new glove box and glove box mounted fuse block that comes with the kit.

Underhood Wiring

The other very busy area of our Early Bronco's wiring system is the under hood area. The headlight/park/turn signal wiring is pretty straightforward and mimics the factory wiring. Our bronco lacks inner fenderwells which is fine with us but means we had to make an aluminum mount for the ignition coil, starter solenoid, Painless Performance supplied Maxi-fuse, and an under hood bus bar for "key on" accessories. The computer for the fuel injection as well as relays for the fuel pump, wiring harness, fuel injection, and so on. We also added a simple yet effective and inexpensive battery box from Summit Racing. This box mounts to the radiator core support and our under hood core support bars.

Classic Instruments Gauge Cluster

One of the nicest parts of our Early Bronco's dash is without doubt this fancy and beautiful Direct Fit Gauge Set from Classic Instruments. The '66-'77 Ford Bronco Package features the speedometer, tachometer, fuel, temperature, volt, and oil gauges all in one direct fit instrument. Installing the all-electronic cluster is easy with the included model specific mounting hardware, Classic Instruments' Zeus Speedometer Technology for push button calibration, and all the included sending units. The unit came with its own little wiring harness that was easy to integrate into the Painless harness and then easily plugs into the back of the cluster. We did have to get fancy with the temp sensor placement for the EFI and gauge cluster as well as the Small Block Ford's oil pressure sending unit.


Multi-Speed Transmission Wiring

Our 6R80 transmission from Performance Automatic is controlled by a US Shift controller and requires some special wiring considerations. For example the shifter and transmission are capable of tap shifting like most modern autos are (check out the article on the shifter here: https://www.fourwheeler.com/how-to/transmission-drivetrain/1912-lokar-automatic-electronic-sport-mode-transmission-shifter-installation/). The transmission controller also needs to know throttle position and provides a vehicle speed sensor to the fuel injection and gauge cluster. The wiring of the transmission as well as the controller isn't simple, but it is easy with the supplied instructions that give you tomes of information on how to make everything do what it should.