Overview
The center of the electric motor control system is a microprocessor called the PCM . The PCM receives inputs from sensors and other electronic components. Based on information received and programmed into its memory, the PCM generates output signals to control various relays, solenoids, and actuators. This vehicle uses two PCM connectors.
The PCM stores information in keep alive RAM (a memory integrated circuit chip) about vehicle operating conditions, and then uses this information to compensate for component variability. Keep Alive Memory (KAM) remains powered when the ignition is off so this information is not lost.
The Vehicle Battery Power (VBPWR) is a PCM -supplied power source that supplies regulated voltage (5 to 12 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. VPWR is the primary source of PCM power. VPWR is switched through the PCM power relay and is controlled by the PCM . The VREF is a positive voltage (about 5 volts) that is output by the PCM. This is a consistent voltage that is used by the three-wire sensors. The Signal Return (SIG RTN) is a dedicated ground circuit used by the sensors and some of the other PCM inputs.
Normal Operation and Fault Conditions
The Ambient Air Temperature (AAT) sensor is a negative temperature coefficient thermistor which senses the outside air temperature. The PCM sends a 5-volt signal to the Ambient Air Temperature (AAT) sensor. Based on the voltage level, the PCM determines the outside temperature. The PCM sends this information to the BECM to the climate control system. When the PCM senses a signal voltage high or voltage signal low, the PCM sets a DTC .
The BPP switch is a dual position switch and receives battery voltage from the BJB fuse 21 (5A). When the brake pedal is applied, a voltage signal is sent to the PCM BPP input. The PCM applies a voltage signal to the BPP switch to determine the brake pedal status. The PCM sets a DTC if one or both of these inputs do not match.
The PCM provides a 5-volt reference voltage to the A/C high and low pressure sensors. The A/C pressure sensors sends a voltage signal to the PCM which indicate the high and low side pressure. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The battery pack coolant control valve is a 12-volt operated valve which regulates coolant to the battery pack. The PCM provides a PWM signal to the pump and monitors this signal by monitoring a diagnostic circuit input. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The PCM controls the low side of the PCM power relay. When the PCM power relay is energized, battery voltage is applied to the various components including the PCM sense input. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The TR sensor has a 6-pin connector. The TR sensor is located on the transmission at the manual lever. The TR sensor sends a signal to the PCM to start the vehicle in PARK and NEUTRAL. The TR sensor uses 2 hall-effect switches that are monitored by the PCM to determine the position of the manual lever. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The motor electronics coolant temperature sensor is a temperature-sensitive device called a thermistor. The resistance value of the motor electronics coolant temperature sensor varies with temperature change. The PCM provides a signal voltage to the motor electronics coolant temperature sensor. The PCM monitors the voltage across the motor electronics coolant temperature sensor to determine the temperature of the electric motor coolant. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The PCM monitors the DC to DC Converter Control Module (DC/DC), PTC heater, the A/C compressor module and the TCM high voltage circuits. The high voltage interlock system verifies these connectors are properly connected. The PCM sends a 5-volt reference signal to each connector, in series and monitors the voltage return. The PCM high voltage interlock sense input checks for continuity of the high-voltage system interlock circuit. The interlock circuit must have continuity before high-voltage is supplied to the vehicle. The interlock circuit voltage travels through each of the high-voltage components and high-voltage cables and back to the PCM. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The PCM monitors the vacuum pump relay input. When the ABS module or the PCM commands the vacuum pump relay on and the PCM did not detect a voltage input, a DTC sets.
There are 2 APP signals in the sensor. Both signals, APP 1 and APP 2, have a positive slope (increasing angle, increasing voltage), but are offset and increase at different rates. The 2 APP signals make sure the PCM receives a correct input even if 1 signal has a concern. The PCM determines if a signal is incorrect by calculating where it should be, inferred from the other signals. If a concern is present with one of the circuits the other input is used. There are 2 reference voltage circuits, 2 signal return circuits, and two signal circuits (a total of 6 circuits and terminals) between the PCM and the APP sensor assembly. The APP signal is converted to pedal travel degrees (rotary angle) by the PCM . The software then converts these degrees to counts, which is the input to the torque based strategy. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The PCM checks the fan control variable output circuit. If the PCM detects the voltage on the fan control variable circuit is not within the expected range then the PCM sets a DTC .
The battery pack coolant temperature sensor is a temperature-sensitive device called a thermistor. The resistance value of the battery pack coolant temperature sensor varies with temperature change. The PCM provides a signal voltage to the battery pack coolant temperature sensor. The PCM monitors the voltage across the battery pack coolant temperature sensor to determine the temperature of the electric motor coolant. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The battery pack coolant pump is a 12-volt pump which can operate at variable speeds. The PCM provides a PWM signal to the pump and monitors this signal by monitoring a diagnostic circuit input. The battery pack coolant pump provides coolant to the battery pack to keep the battery warm by providing warm coolant and to keep the battery cool as it begins to generate heat.
When the PCM is powered up the PCM sends a 12-volt signal to the secondary on-board diagnostic module A as a wake up input. The secondary on-board diagnostic module A begins communicating on the high speed CAN . The PCM sets a DTC if voltage on this input is above or below a calibrated threshold.
The drive motor coolant pump is a 12-volt pump which operates at variable speeds. The PCM provides a PWM signal to the pump and monitors this signal by monitoring a feedback circuit. The drive motor coolant pump provides coolant to the drive motor to keep the motor warm by providing warm coolant and to keep the motor cool as it begins to generate heat.
The battery pack coolant heater elements are used to warm the coolant when temperatures drop below a calibrated limit. When the vehicle is started, the PCM commands one or all of the battery pack coolant heater elements to come on. The PCM sets a DTC if voltage on these battery pack coolant heater element inputs are above or below a calibrated threshold.
The PCM provides a 5-volt reference voltage to the BARO sensor. The BARO sensor sends a voltage signal to the PCM which indicate atmospheric pressure. The barometric sensor is used in conjunction with the TPMS. The PCM sets a DTC if voltage on this input is above or below a calibrated threshold.
The PCM sends a signal to the BCM which commands the ignition relay on. The PCM monitors the ignition relay and crank detect inputs for voltage. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The PCM receives a voltage signal from the BCM which alerts the PCM to wake up or shut down. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The engine coolant bypass valve is a 12-volt operated valve which regulates coolant to the electric motor. The PCM provides a PWM signal to the pump and monitors this signal by monitoring a diagnostic circuit input. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The PCM receives a wake-up signal from the BECM. The PCM sets a DTC if voltage on this input is above a calibrated threshold.
The PCM controls the low side of the PCM contactor relay. When the PCM contactor relay is energized, battery voltage is applied to the various components including the PCM contactor sense input. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The cabin heater coolant pump is a 12-volt pump which can operate at variable speeds. The PCM provides a PWM signal to the pump and monitors this signal by monitoring a diagnostic circuit input. The cabin heater coolant pump provides coolant to the battery pack to keep the battery warm by providing warm coolant and to keep the battery cool as it begins to generate heat.
The PCM sends a 12-volts to the PTC engine coolant heater. The PCM monitors the heater enable and heater PWM input voltage. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The PTC cabin coolant heater temperature sensor is a temperature-sensitive device called a thermistor. The resistance value of the PTC cabin coolant heater temperature sensor will vary with temperature change. The PCM provides a signal voltage to the PTC cabin coolant heater temperature sensor. The PCM monitors the voltage across the PTC cabin coolant heater temperature sensor to determine the temperature of the cabin coolant. The PCM sets a DTC if voltage on this input is above or below a calibrated threshold.
The PCM continuously monitors the CAN for messages from the TCM . This DTC sets when the PCM does not receive the TCM message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the BECM. This DTC sets when the PCM does not receive the BECM message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the ABS. This DTC sets when the PCM does not receive the ABS message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the BCM . This DTC sets when the PCM does not receive the BCM message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the RCM . This DTC sets when the PCM does not receive the RCM message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the IPC module. This DTC sets when the PCM does not receive the IPC module message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the HVAC module. This DTC sets when the PCM does not receive the HVAC module message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the GPS module. This DTC sets when the PCM does not receive the GPS module message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the ACCM . This DTC sets when the PCM does not receive the electronic ACCM message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the TCU . This DTC sets when the PCM does not receive the TCU message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the Secondary OBD Module A. This DTC sets when the PCM does not receive the Secondary OBD Module A message within the defined amount of time.
The PCM continuously monitors the CAN for messages from the DC to DC Converter Control Module (DC/DC). This DTC sets when the PCM does not receive the DC to DC Converter Control Module (DC/DC) message within the defined amount of time.
The PCM provides a ground input which energizes the cabin air conditioning isolator solenoid valve which diverts refrigerant to the cabin coolant heater. The PCM sets a DTC if voltage on this input is above or below a calibrated threshold.
The engine coolant bypass valve is a 12-volt operated valve which regulates coolant to the elecric motor. The PCM provides a PWM signal to the pump and monitors this signal by monitoring a diagnostic circuit input. The PCM sets a DTC if voltage on these inputs are above or below a calibrated threshold.
The PCM sends a signal to the vehicle audio signal pedestrian module when the PCM receives a CAN signal from the Parking Aid Module (PAM) indicating an object is behind the vehicle. The PCM sets a DTC if voltage on this input is above or below a calibrated threshold.
The PCM receives a wake up voltage signal from the BCM . The PCM provides a ground to energize the PCM power relay. Battery and ignition voltage is then applied to the PCM . The PCM provides 12 volt and 5 volt reference voltage to various solenoids and components.
The PCM and TCM share torque calculations between each module. If a short to ground, short to power or an open circuit is detected on this circuit, then the DTC sets.