Powertrain Control Module (Pcm)

The PCM operates the fuel system. The PCM is a pre-programmed, dual microprocessor digital computer. It regulates ignition timing, air-fuel ratio, emission control devices, charging system, certain transmission features, speed control, air conditioning compressor clutch engagement and idle speed. The PCM can adapt its programming to meet changing operating conditions.

The PCM receives input signals from various switches and sensors. Based on these inputs, the PCM regulates various engine and vehicle operations through different system components. These components are referred to as Powertrain Control Module (PCM) Outputs. The sensors and switches that provide inputs to the PCM are considered Powertrain Control Module (PCM) Inputs.

The PCM adjusts ignition timing based upon inputs it receives from sensors that react to: engine RPM, manifold absolute pressure, engine coolant temperature, throttle position, pedal value, transmission gear selection (automatic transmission), vehicle speed and the brake switch.

The PCM adjusts idle speed based on inputs it receives from sensors that react to: throttle position, vehicle speed, transmission gear selection, engine coolant temperature and from inputs it receives from the air conditioning clutch switch and brake switch.

Based on inputs that it receives, the PCM adjusts ignition coil dwell. The PCM also adjusts the generator charge rate through control of the generator field and provides speed control operation.

1. A/C select & request via CAN communication bus
2. Auto shutdown (ASD) sense
3. Brake switches 1 & 2
4. Direct Battery voltage
5. EGR Position sensor
6. EVAP purge solenoid current sense
7. Camshaft position sensor signal
8. Crankshaft position sensor
9. CAN C bus communication for internal module communication and data link connection for scan tools
10. Engine coolant temperature sensor
11. 5 volts (primary)
12. 5 volts (secondary)
13. Fuel level via CAN communication bus from IPM
14. Generator (battery voltage sense) output
15. Ignition circuit sense (ACC & Run/Start via hardwire from Integrated Power Module (IPM) while the Crank indication is via CAN communication bus)
16. Intake manifold air temperature sensor
17. Evaporative system ESIM vacuum switch (if equipped)
18. Manifold absolute pressure (MAP) sensor
19. Oil pressure
20. Oxygen sensors signals
21. Park/neutral switch
22. Power ground
23. Sensor return
24. Signal ground
25. Speed control switch states are determined by SCM and transmitted over the bus via CAN bus
26. SRV position sensor signal
27. Throttle position sensors and Pedal value sensors
28. Transmission pressure switch inputs (42RLE)
29. Transmission variable line pressure sensor (42RLE)
30. Transmission temperature sensor (42RLE)
31. Vehicle speed (ABS equipped) via CAN C bus from ABS module
32. Vehicle Speed (Non-ABS) from IPM via CAN C and Trans Turbine sensors (with pinion factor)

1. A/C clutch relay
2. Auto shutdown (ASD) relay coil
3. CAN C bus messages for speedometer (non-ABS packages), voltmeter or generator lamp (if equipped), fuel gauge, oil pressure gauge/lamp, engine coolant temperature gauge and speed control indication warning lamp
4. CAN bus communication for inter module communication and data link connection for scan tools
5. EGR valve control solenoid (if equipped)
6. Electronic Throttle Control (ETC) motor
7. EVAP Purge solenoid
8. Fuel injectors
9. Fuel pump relay
10. Generator field driver
11. Ignition coils
12. Malfunction indicator lamp (also known as MIL). Driven through Bus Messages.
13. Oxygen sensor heater elements
14. Radiator cooling fan relay via CAN bus message to IPM
15. Short Runner Valve (SRV) actuator (if equipped)
16. Tachometer (if equipped). Driven through Bus Messages.
17. Transmission solenoids (42RLE only)
18. Transmission power relay