t one time, classic trucks like the 1955 Ford F-100 owned by Paul Willis were basic utilitarian vehicles. This particular example came from the factory with a 239 Y-block V-8 and a three-speed manual transmission. The windshield wipers were vacuum operated and the only option was a heater. But like most of us during the rebuilding process, Paul elected to make some updates to the pickup. He decided to add A/C, power windows, electric wipers, new instrumentation, and a stereo. Of course, all these updates would require updating the electrical system, which is simple enough to do with a new wiring harness like those available from American Autowire.

Along with the added convenience items inside the cab, Paul decided to make some changes underhood as well. His powerplant of choice is a Chevrolet Gen V direct-injected L83 V-8 backed by a 6L80 automatic transmission from a 2015 Tahoe. To control the engine and transmission’s functions a wiring harness from Howell Performance was used. This stand-alone system uses modified factory engine and transmission ECMs (electronic control modules) to control their functions and includes a check-engine light, diagnostic connector, and electric fan control.

To replace the truck’s dilapidated wiring harness, Paul turned to American Autowire for their Classic Update Kit. These wiring systems are designed for specific vehicles (as opposed to a universal-style kit) and provide more circuits than would have been available in an original chassis or factory-style replacement harness. The Classic Update engine harness provides for updated engine and transmission combinations, while the front light and rear body harness have extra-long leads for custom routing. A 175-amp mega fuse kit with six-gauge charge cable to support a high-output charging system and internally regulated alternator is also supplied. Original-replacement connectors, terminals, and lamp sockets, a headlight switch with 26-amp internal circuit breaker, and new floor dimmer switch are also included, along with a replacement ignition switch compatible with HEI and EFI swaps.

One of the modifications made to the cab of Paul’s hauler was the installation of a 1957 Ford passenger car dashboard that has been updated with a Dakota Digital instrument panel. The VHX System fits directly into the 1957 dashboard without modification. The state-of-the-art panel has analog gauges that include an electronic speedometer, tachometer, oil pressure, water temperature, and fuel level gauges. A digital message center displays the voltmeter, odometer, dual trip meters, clock, and much more (including digital gauge readouts). A unique feature of the VHX instrument panel is the ability to configure the gauges with warning points that appear in the message center. The voltmeter can be configured to flash whenever the voltage drops below the warning value, which can be set from 10 to 13.1 V. The temperature gauge can be set to indicate a high-temperature warning point that will cause a warning message to display; likewise, low oil pressure will cause the message center to flash whenever the value is lower than the warning set point.

While installing the American Autowire harness, the engine management system and the Dakota Digital instrument panel are all normally straightforward; in this case, the three systems had to be integrated. The wires in the American Autowire harness that normally connect to the starter and ignition switch were connected to the engine’s ECU, which in turn controlled those engine functions. As the ECU also has outputs for engine rpm, temperature, and oil pressure at the OBD II (on-board diagnostics) port from factory sensors, those outputs can be used to operate the Dakota Digital instruments, thereby eliminating the need for additional sender. However, the “signals” the ECU provides cannot be connected directly to the instruments so Dakota Digital offers an “interface” module that converts the ECU’s signals to something the instrument panel can read.

While combining American Autowire with the engine management seems complicated at first, it’s really a simple matter of changing a few connections. In simple terms the ECM controls the engine’s functions—starter, ignition, and fuel injection system—and the American Autowire system will control the ECM. In addition, as the ECM has outputs to supply “information” the Dakota Digital instrument panel requires, no senders are necessary (other than the fuel level sender). The remainder of the electrical items, such as lights and accessories, are connected by the American Autowire harness as they normally would be.

Like any other wiring installation American Autowire suggests that the terminals that may have to be installed are properly crimped (American Autowire has the proper crimping tools available). Note that all crimped terminations already installed are done on a GM-approved 5-ton presses, and soldering these terminations is not necessary. The key to success is to follow the relevant instructions, make sure all ground connections are clean and tight and the wires are protected with grommets where they pass through holes in the sheetmetal and your classic truck will be well connected.