Powertrain Control Hardware
POWERTRAIN CONTROL HARDWAREClean Tachometer Output (CTO)
The powertrain control module (PCM) uses a crankshaft position (CKP) sensor input to calculate the engine speed. The engine speed information is then output to the TCM through the CTO circuit, as a frequency signal. The PCM also broadcasts a redundant engine speed message to the TCM over the controller area network (CAN) communication link. When the broadcasted engine speed disagrees with the hardwired CTO signal, or when the CTO circuit concern condition is detected, the TCM stores an appropriate diagnostic trouble code (DTC).
Fuel Pump Control Module
The fuel pump control module receives a duty cycle signal from the PCM and controls the fuel pump operation in relation to this duty cycle. The PCM requests low or high speed fuel pump operation depending on engine fuel demand. The fuel pump control module controls the fuel pump by switching the fuel pump power circuit on and off at the required duty cycle. The fuel pump control module sends diagnostic information to the PCM on the fuel pump monitor circuit. For additional information on the fuel pump control and the fuel pump monitor, refer to Fuel System.
Integrated Electronic Ignition (EI) System
The EI system consists of a crankshaft position (CKP) sensor, ignition coils, connecting wiring, and PCM. The coil on plug (COP) integrated EI system uses a separate coil for each spark plug and each coil is mounted directly onto the plug. The COP integrated EI system eliminates the need for spark plug wires, but requires input from the camshaft position (CMP) sensor.
Ignition Switch Position Run (ISP-R)
The ISP-R provides the PCM with a VBAT input signal from the ignition switch, indicating the ignition is in either the ON or START position. When the operator turns the ignition to the OFF or ACC position, the internal combustion engine immediately ceases to provide power. The PCM coordinates the power down sequence by controlling the VPWR circuit and issuing the correct commands to shut down the electrical system in an orderly fashion. For additional information, refer to the Normal Power Down Sequence in Hybrid Electric Control Software. The PCM maintains power to the TCM through the VPWR until the power down sequence is complete. The battery energy control module (BECM) is always powered directly from the low voltage battery which permits wake-up when the vehicle is off.
Ignition Switch Position Run/Start (ISP-RS)
The ISP-RS provides the PCM with a VBAT input signal from the ignition switch, indicating the ignition is in the START position.
Powertrain Control Module (PCM)
The center of the electronic engine control (EEC) system is a microprocessor called the PCM. The PCM receives input 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. The hybrid vehicle uses a 190-pin PCM which has three separate electrical harness connectors.
PCM Location
The PCM is located in the engine compartment, driver side, mounted to the cowl between the transmission and the cowl.
Powertrain Control Module (PCM) Keep Alive Memory (KAM)
The PCM stores in KAM (a memory integrated circuit chip) information about vehicle operating conditions, and then uses this information to compensate for component variability. KAM remains powered when the ignition is off so this information is not lost.
Powertrain Control Module (PCM) Power and Ground Signals
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)
VPWR is the primary source of PCM power. VPWR is switched through the PCM power relay and is controlled by the PCM.
Reference Voltage (VREF)
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.
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.
Signal Return (SIG RTN)
The SIG RTN is a dedicated ground circuit used by most EEC sensors and some other inputs.
Power Ground (PWR GND)
The PWR GND is an electric current path return for VPWR voltage circuit. The purpose of the PWR GND is to maintain sufficient voltage at the PCM.
Gold Plated Pins
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. Replace damaged gold terminals with new gold terminals.