Power and Ground Signals

Power and Ground Signals

Vehicle Power

VPWR is the primary source of PCM power. VPWR is switched through the electronic engine control (EEC) power relay and is controlled by the ignition switch.

Vehicle REFERENCE Voltage

VREF is a consistent positive voltage (5.0 volts ± 0.5) provided by the PCM. VREF is typically used by 3-wire sensors and some digital input signals.

Mass Air Flow Return

The mass air flow return (MAP RTN) is a dedicated analog signal return from the mass air flow (MAF) sensor. If serves as a ground offset for the analog voltage differential input by the MAF sensor to the PCM.

Signal Return

The signal return (SIG RTN) is a dedicated ground circuit used by most electronic EC sensors and some other inputs.

Power Ground

The PWR GND circuit(s) is directly connected to the battery negative terminal. PWR GND provides a return path for the PCM VPWR circuits.

Gold Plated Pins

NOTE: Gold plated terminals should only be replaced with new gold plated terminals.

Some engine control hardware has gold plated pins on the connectors and mating harness connectors to improve electrical stability for low current draw circuits and to enhance corrosion resistance. The electronic EC components equipped with gold terminals will vary by vehicle application.