Power and Ground Signals

Accelerator Pedal Position Reference Voltage (APPVREF) 

The APPVREF is a consistent positive voltage (5 volts plus or minus 0.5 volt) circuit.

Accelerator Pedal Position Return (APPRTN) 

The APPRTN is a return path for APPVREF circuit.

Electronic Throttle Control Reference Voltage (ETCREF) 

The ETCREF is a consistent positive voltage (5 volts plus or minus 0.5 volt) circuit.

Electronic Throttle Control Return (ETCRTN) 

The ETCRTN is a return path for ETCREF circuit.

Gold Plated Pins 

Some engine control hardware has gold plated pins within the connectors and mating harness connectors to improve electrical stability for low current draw circuits and to enhance corrosion resistance. The engine control (EC) components equipped with gold plated pins vary by vehicle application. Only replace gold plated pins with new gold plated pins.

Keep Alive Power (KAPWR) 

The KAPWR provides a constant voltage input independent of ignition switch state to the PCM. This voltage is used by the PCM to maintain the KAM.

Power Ground (PWRGND) 

The PWRGND circuits provides a return path for the PCM vehicle power (VPWR) circuits.

Signal Return (SIGRTN) 

The SIGRTN is a dedicated return path for VREF applied components.

Variable Reluctance Sensor Return (VRSRTN) 

The VRSRTN circuit is a dedicated return path for variable reluctance (VR) type sensors.

Vehicle Buffered Power (VBPWR) 

The VBPWR is a regulated voltage supplied by the PCM to vehicle sensors. These sensors require a constant 12 volts for operation and cannot withstand VPWR voltage variations. The VBPWR is regulated to VPWR minus 1.5 volts and is also current limited to protect the sensors.

Vehicle Power (VPWR) 

The VPWR is the primary source of PCM power. VPWR is switched through the PCM power relay.

Vehicle Reference Voltage (VREF) 

There are 2 different types of reference voltages supplied by the PCM for use with engine related sensors. One source would be Voltage Reference (VREF) which is a 5-volt source. Another is Vehicle Buffered Power (VBPWR) which is a regulated 12-volt source. These sources are supplied to the sensor to provide more stable and accurate input to the PCM since the voltage is consistent. The PCM can have up to 3 internal sources of VREF and one source of VBPWR (if equipped). Each of these sources can be connected to multiple external circuits, with separate PCM terminals for each circuit. These circuits can then be connected to one or more sensors as needed.

Due to variations that occur over the different vehicle lines and engines used in each line, there are a variety of different sensor layouts used. Reference voltages are supplied to the sensors that require it for proper operation. In some cases, reference voltage faults can be indicated by multiple sensor faults relating to circuit high, circuit low, or sensor performance despite no external shared connections due to these internal BUS connections that are shared between the affected sensors.

Although a steady 5 volts to VREF sensors is desired, this voltage can vary between 4.5 - 5.5 volts. The VREF PID within the PCM does not display the actual output voltage the PCM is supplying to these sensors. This PID only reflects an internal module VREF that is unrelated to the VREF output BUS's.