August 23, 2020
8
Connect the Engine and Power
Before connecting the power, DISCONNECT THE BATTERY.
Follow the wiring diagram to make the connections. For those cables not in use, leave them in place and
secure the stripped end with wiring tape.
1. Connect the Throttle Position Sensor
From the harness assembly, attach the cable marked “TPS” to your vehicle’s AccuLink TPS, EFI TPS
adapter, or Cable TPS system.
Optional: CAN Bus Connector
Certain versions of the HGM software can obtain throttle position, engine speed, manifold
pressure, manifold temperature and other information directly from the ECU through the CAN
bus. If applicable, connect the plug marked CAN to your vehicle’s ECM.
2. Connect the Power, Meter, and Optional Switch Leads
From the harness assembly:
Connect the purple/white wire marked “SPEEDO OUT” to the speedometer.
Connect the black wire marked “GRND” to a good ground.
Connect the brown wire marked “TACH IN” to either the tachometer output of an electronic
ignition system (for example, an HEI), or the tachometer output of an MSD ignition system.
Connect the red wire marked “+ 12 SWITCHED” to a circuit that’s powered when your ignition
switch is turned to the “ON” position – NOT accessory “ACC” position (min. 6 amps of current).
Optional: Connect a Mode Switch and Mode LED.
Most harnesses are equipped with wires for a mode switch and mode. These allow you to change
between two preset calibrations, A and B, on the controller by pressing a pushbutton. The
pushbutton should be a momentary switch to ground. See the section below on “Using Optional
Features.”
Optional: Connect an Overdrive Cancel Switch and LED
Depending on the transmission type, some harnesses are equipped with wires for an overdrive
cancel switch and overdrive cancel LED. An LED connected from the OD CANCEL LED wire to ground
will light when the overdrive function is cancelled. The overdrive cancel switch is usually wired as a
momentary switch to ground but can be configured as a toggle switch instead. See the section
below on “Using Optional Features.”
Optional: Connect a Manual TCC Switch and TCC LED
