Powertrain Control Module (Pcm)

The PCM is a pre-programmed, 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, 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. Accelerator pedal position sensor (if equipped)
2. A/C request (if equipped with factory A/C)
3. A/C select (if equipped with factory A/C)
4. Auto shutdown (ASD) sense
5. Battery temperature
6. Battery voltage
7. Brake switch
8. CAN bus (+) circuits
9. CAN bus (-) circuits
10. Camshaft position sensor signal
11. Clutch Interlock Switch (if equipped)
12. Crankshaft position sensor
13. Data link connection for diagnostic scan tool
14. EGR position sensor (if equipped)
15. Engine coolant temperature sensor
16. Fuel level
17. Generator (battery voltage) output
18. Ignition circuit sense (ignition switch in on/off/crank/run position)
19. Intake manifold air temperature sensor
20. Knock sensor(s) (if equipped)
21. Leak detection pump (switch) sense (if equipped)
22. Manifold absolute pressure (MAP) sensor
23. Oil pressure sensor
24. Output shaft speed sensor
25. Overdrive/override switch
26. Oxygen sensors
27. Park/neutral switch (auto. trans. only)
28. Power ground
29. Power steering pressure switch (if equipped)
30. Sensor return
31. Signal ground
32. Speed control multiplexed single wire input
33. Throttle position sensor
34. Transmission governor pressure sensor
35. Transmission output speed sensor
36. Transmission temperature sensor
37. Vehicle speed inputs from ABS or RWAL system

1. A/C clutch relay
2. Auto shutdown (ASD) relay
3. CAN bus (+/-) circuits for: speedometer, voltmeter, fuel gauge, oil pressure gauge/lamp, engine temp. gauge and speed control warn. lamp
4. Data link connection for diagnostic scan tool
5. Double start override (if equipped)
6. EGR valve control solenoid (if equipped)
7. Electronic throttle control
8. EVAP canister purge solenoid
9. Five volt sensor supply (primary)
10. Five volt sensor supply (secondary)
11. Fuel injectors
12. Fuel pump relay
13. Generator field driver (-)
14. Generator field driver (+)
15. Generator lamp (if equipped)
16. Idle air control (IAC) motor
17. Ignition coil(s)
18. CAN bus circuits
19. Leak detection pump (if equipped)
20. Malfunction indicator lamp (Check engine lamp). Driven through CAN bus circuits.
21. Overdrive indicator lamp (if equipped)
22. Radiator cooling fan (if equipped)
23. Speed control vacuum solenoid
24. Speed control vent solenoid
25. Starter relay
26. Tachometer (if equipped). Driven through CAN bus circuits.
27. Transmission convertor clutch circuit
28. Transmission 3-4 shift solenoid
29. Transmission relay
30. Transmission temperature lamp (if equipped)
31. Transmission variable force solenoid