Vehicle applicability: This diagnostic supplement covers multiple Ford vehicles and engines. Follow the application named in the source below. Some references apply to vehicles other than Mustang.
1-50 Description and Operation
Powertrain Control Hardware
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.
Mass Airflow Return (MAFRTN)
The MAFRTN is a signal return circuit from the mass airflow (MAF) sensor.
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.
Starter Motor Request (SMR) Circuit
The SMR circuit provides the PCM with a signal from the ignition switch to the PCM. The input is pulled high when the ignition is in the START position and the transmission range (TR) sensor ignition lockout circuit allows the starter to engage.
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. 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)
The VREF is a consistent positive voltage (5 volts plus or minus 0.5 volt) provided by the PCM. VREF is typically used by 3-wire sensors and some digital input signals.
2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.