Operation - ECM

The main function of the Engine Control Module (ECM) is to electrically control the fuel system. The ECM also controls certain transmission and other functions previously controlled by the Powertrain Control Module (PCM).

The ECM can adapt its programming to meet changing operating conditions.

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

1. Accelerator Pedal Position Sensor (APPS) Signals #1 and #2
2. AC system pressure
3. Auto shutdown (ASD) sense
4. Battery temperature
5. Battery temperature sensor
6. Battery voltage
7. Brake switch
8. Camshaft Position Sensor (CMP)
9. Crankshaft Position Sensor (CKP)
10. Data link connection for DRB scan tool
11. Engine Coolant Temperature (ECT) sensor
12. EATX module (if equipped)
13. Fuel level
14. Fuel pressure sensor
15. Fan speed (engine cooling fan)
16. Generator (battery voltage) output
17. Governor pressure (Auto. trans.)
18. Ground circuits
19. Inlet air temperature sensor/pressure sensor
20. Intake air temperature sensor/MAP sensor
21. J1850 bus (+) circuits
22. J1850 bus (-) circuits
23. Key switch (ignition)
24. Oil Pressure switch
25. Overdrive switch (automatic transmission only)
26. Park/neutral switch (auto. trans. only)
27. Power ground
28. SCI datalink bus (+) circuits
29. SCI datalink bus (-) circuits
30. Sensor return
31. Signal ground
32. Speed control multiplexed single wire input
33. Transfer case switch (4WD range position)
34. Transmission governor psi (automatic transmission only)
35. Transmission OSS (automatic transmission only)
36. Transmission oil pressure (automatic transmission only)
37. Transmission oil temperature (automatic transmission only)
38. Transmission throttle valve position (automatic transmission only)
39. Vehicle speed signal
40. Water-In-Fuel (WIF) sensor

After inputs are received by the ECM, certain sensors, switches and components are controlled or regulated by the ECM. These are considered ECM Outputs.  These outputs are for:

1. A/C clutch relay
2. Auto shutdown (ASD) relay
3. Data link connection for DRB scan tool
4. Fan clutch PWM
5. Five volt sensor supply (primary)
6. Five volt sensor supply (secondary)
7. Fuel control actuator
8. Fuel injector driver circuits
9. Fuel transfer (lift) pump
10. Generator field driver (-)
11. Generator field driver (+)
12. Governor pressure (VFS solenoid)
13. Intake manifold air heater relays #1 and #2 control circuits
14. J1850 bus (+/-) circuits for: speedometer, voltmeter, fuel gauge, oil pressure gauge/lamp, engine temp. gauge and speed control warn. lamp
15. Malfunction indicator lamp (Check engine lamp). Driven through J1850 circuits.
16. Oil pressure switch/warning lamp (databus)
17. Overdrive/3-4 shift solenoid (automatic transmission only)
18. SC source
19. SCI datalink bus (+) circuits
20. SCI datalink bus (-) circuits
21. Speed control vacuum solenoid
22. Speed control vent solenoid
23. Tachometer (if equipped). Driven through J1850 circuits.
24. TCC solenoid (automatic transmission only)
25. Transmission battery relay (automatic transmission only)
26. Transmission throttle valve actuator (automatic transmission only)
27. Transmission governor psi solenoid (automatic transmission only)
28. Wait-to-start warning lamp (databus)
29. Turbo wastegate solenoid
30. Water-In-Fuel (WIF) warning lamp (databus)