Power and Ground Signals

Power and Ground Signals

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.

Keep Alive Power (KAPWR)
KAPWR provides a constant voltage input independent of ignition switch state to the PCM. This voltage is used by the PCM to maintain the keep alive memory (KAM).

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

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

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

Vehicle Buffered Power (VBPWR)
The VBPWR is a PCM-supplied power source that supplies regulated voltage (10 to 14 volts) to vehicle sensors that run off 12 volts but cannot withstand VPWR voltage variations. It is regulated to VPWR minus 1.5 volts and is voltage limited to protect the sensors.

Vehicle Power (VPWR)
When the key is turned to the ON or START position, battery positive voltage (B+) is applied to the coils of the EEC power relay and power sustain relay (PSR). Since the other end of the coils are wired to ground, this energizes the coils and closes the contacts of the EEC power relay and PSR. VPWR is now supplied to the PCM and the EEC system as VPWR. When the key is turned to the OFF position, the PCM keeps the PSR energized until the normal power-down sequence is completed. See Engine Control Components, Power Sustain Relay.

Vehicle Reference Voltage (VREF)
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.