Powertrain Control Module (PCM) Outputs
POWERTRAIN CONTROL MODULE (PCM) OUTPUTSAir Conditioning (A/C) Clutch Relay
The A/C clutch relay (may be referred to as the wide open throttle A/C cutoff relay) is wired normally open. There is no direct electrical connection between the A/C switch or electronic automatic temperature control (EATC) module and the A/C clutch. The PCM receives a signal indicating that A/C is requested. When A/C is requested, the PCM checks other A/C related inputs that are available. If these inputs indicate A/C operation is OK, and the engine conditions are OK (coolant temperature, engine RPM, throttle position), the PCM grounds the WAC output, closing the relay contacts and sending voltage to the A/C clutch.
Air Conditioning (A/C) Refrigerant Distribution Valve (ACRDV)
Air Conditioning (A/C) Refrigerant Distribution Valve (ACRDV):
The ACRDV is a PCM controlled solenoid which provides a regulated control of refrigerant flow to the passenger compartment loop. The PCM opens or closes the ACRDV based on the passenger compartment A/C request. The ACRDV is a normally closed valve, preventing the refrigerant flow. When the passenger compartment A/C is requested ON, the PCM provides a ground path to the solenoid which opens the ACRDV.
Canister Vent Solenoid
For information on the canister vent solenoid, refer to the description of the Evaporative Emission (EVAP) System.
Clean Tachometer Output (CTO)
The PCM uses a crankshaft position (CKP) sensor input to calculate the engine speed. The engine speed information is then output to the transaxle control module (TCM) through the CTO circuit, as a frequency signal. The PCM also broadcasts a redundant engine speed message to the TCM over the CAN communication link. When the broadcasted engine speed disagrees with the hardwired CTO signal, or when the CTO circuit fault condition is detected, the TCM stores an appropriate diagnostic trouble code (DTC).
Coil On Plug (COP)
For information on the COP refer to the description of the Ignition System.
DC/DC Enable (DCE)
The DCE is an output from the PCM to the DC/DC converter. The PCM enables the DC/DC converter after the PCM receives a contactors closed message and no error messages. The DCE circuit is high (the low side driver is off) when the DC/DC is commanded on. When the DCE low side driver is activated, the DC/DC converter is commanded off. For additional information on DCE, refer to the DC/DC converter description in Hybrid Electric Control Hardware. Description and Operation
Exhaust Gas Recirculation (EGR) System
For information on the electric EGR system, refer to Exhaust Gas Recirculation (EGR) System. Description and Operation
Fan Control
PCM Output State For Cooling Fan Speeds:
The hybrid vehicle uses a relay controlled fan system. The PCM monitors certain parameters (engine coolant temperature, vehicle speed, A/C ON/OFF status, and A/C pressure) to determine engine cooling fan needs. The PCM controls the fan operation through the low fan control (LFC), medium fan control (MFC), and high fan control (HFC) outputs.
For 3-speed fans, although the PCM output circuits are called low, medium, and high fan control (FC), cooling fan speed is controlled by a combination of these outputs. Refer to the table.
Fuel Injectors
For information on the fuel injectors, refer to the description of the Fuel System.
Fuel Pump (FP)
Fuel Pump Duty Cycle Output From PCM:
The fuel pump (FP) signal is a duty cycle command sent from the PCM to the fuel pump driver module (FPDM). The FPDM uses the FP command to operate the fuel pump at the speed requested by the PCM or to turn the pump off.
Fuel Tank Isolation Valve (FTIV)
For information on the FTIV, refer to the description of the Evaporative Emission (EVAP) System.
Generator Shut Down (GSDN)
The PCM keeps the generator motor inverter enabled by continuously toggling the GSDN output. Typical output frequency varies between 49 and 75 Hz at 50% duty cycle. The PCM also broadcasts a redundant not shutdown message to the transaxle control module (TCM) over the communication link. When a fault condition is detected, the PCM stops generating this frequency signal and broadcasts a shutdown message to the TCM over the communication link. The TCM then disables the generator motor inverter and sets an appropriate DTC. In the event of GSDN circuit failure, the PCM still broadcasts a not shutdown message but the hard wire signal frequency is out of expected range. The TCM then disables the generator motor inverter and sets the appropriate DTC.
Heater Pump
Heater Pump:
The heater pump is required to maintain engine coolant flow to the heater core for passenger compartment heating, when the engine is not running. The PCM commands the heater pump ON by energizing the heater pump control relay (HPCR).
The pump is commanded on when the following conditions are met:
- The key is in ON/START position.
- The engine coolant temperature is above a minimum threshold 0°C (32°F) nominal.
- The inferred ambient temperature is below a calibrated value 32°C (90°F) nominal.
- The engine speed is below a calibrated threshold (nominal 4,000 RPM) including engine OFF.
- The climate control mode switch is in any position other than OFF.
The pump is off when the climate control mode switch is set to OFF.
Motor Electronics Cooling Pump (MECP)
Motor Electronics Cooling Pump:
Motor Electronics Coolant Flow:
The motor electronics cooling system is required to maintain an acceptable temperature for the transaxle and the DC/DC converter. The system temperature is monitored by the motor electronics coolant temperature (MECT) sensor, which is an input to the PCM. The PCM commands the MECP using the MECP relay. The MECP is commanded on whenever the traction battery contactors are closed. The coolant in the system flows in a loop from the MECP, to the DC/DC converter, to the top hose port of the motor electronics radiator, out of the motor electronics radiator bottom hose port, into the transaxle, and back into the MECP. The cooling system has a degassing system built into the loop that bleeds air/gases into the coolant reservoir.
Motor Shut Down (MSDN)
The PCM keeps the traction motor inverter enabled by continuously toggling the MSDN output. Typical output frequency varies between 49 and 75 Hz at 50% duty cycle. The PCM also broadcasts a redundant not shutdown message to the transaxle control module (TCM) over the communication link. When a fault condition is detected, the PCM stops generating this frequency signal and broadcasts a shutdown message to the TCM over the CAN communication link. The TCM then disables the traction motor inverter and sets an appropriate DTC. In the event of MSDN circuit failure, the PCM still broadcasts a not shutdown message but the hard wire signal frequency is out of expected range. The TCM then disables traction motor inverter and sets the appropriate DTC.
Power Sustain Relay (PSR)
The PSR is wired in parallel with the electronic engine control (EEC) power relay. The PCM and transaxle control module (TCM) use the power sustain relay to keep the modules powered. The PCM and TOM must be powered to complete the normal power down sequence, after key is turned to OFF or ACCS position. For more information on normal power down sequence, refer to Hybrid Electric Control Software. When the ignition key is cycled from the OFF to ON or the ON/START position, the PCM smart driver grounds the PSR circuit. The PSR coil is energized and it closes the contacts of the PSR supplying the modules with the B+ power. The PSR coil stays energized after the key is turned to the OFF or the ACCS position until normal power down sequence is successfully completed. The PCM monitors the PSR output for an open and short circuit fault condition. The PSR circuit shorted to ground fault condition keeps the modules powered at all times and it may cause an excessive key off load on the low voltage system. Description and Operation
NOTE: The injectors and ignition coils are powered through a dedicated coil/injector relay so that the engine stops running when the ignition key is turned to the OFF position.
Throttle Actuator Control (TAC) Motor
For information on the TAC motor, refer to the Torque Based Electronic Throttle Control (ETC). Description and Operation
Vapor Management Valve (VMV)
For information on the VMV (EVAP canister purge valve), refer to the description of the Evaporative Emission (EVAP) System.