Engine Control Module - Operation

OPERATION

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.

NOTE: ECM Inputs:

- Accelerator Pedal Position Sensor (APPS) Signals #1 and #2
- AC system pressure
- Auto shutdown (ASD) sense
- Battery temperature
- Battery temperature sensor
- Battery voltage
- Brake switch
- Camshaft Position Sensor (CMP)
- Crankshaft Position Sensor (CKP)
- Data link connection for a scan tool
- Engine Coolant Temperature (ECT) sensor
- EATX module (if equipped)
- Fuel level
- Fuel pressure sensor
- Fan speed (engine cooling fan)
- Generator (battery voltage) output
- Governor pressure (Auto. trans.)
- Ground circuits
- Inlet air temperature sensor/pressure sensor
- Intake air temperature sensor/MAP sensor
- CAN C BUS (+) circuits
- CAN C BUS (-) circuits
- Key switch (ignition)
- Oil Pressure switch
- Overdrive switch (automatic transmission only)
- Park/neutral switch (auto. trans. only)
- Power ground
- SCI datalink bus (+) circuits
- SCI datalink bus (-) circuits
- Sensor return
- Signal ground
- Speed control multiplexed single wire input
- Transfer case switch (4WD range position)
- Transmission governor psi (automatic transmission only)
- Transmission OSS (automatic transmission only)
- Transmission oil pressure (automatic transmission only)
- Transmission oil temperature (automatic transmission only)
- Transmission throttle valve position (automatic transmission only)
- Vehicle speed signal
- Water-In-Fuel (WIF) sensor

NOTE: ECM Outputs:

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:

- A/C clutch relay
- Auto shutdown (ASD) relay
- Data link connection for diagnostic scan tool
- Fan clutch PWM
- Five volt sensor supply (primary)
- Five volt sensor supply (secondary)
- Fuel control actuator
- Fuel injector driver circuits
- Fuel transfer (lift) pump
- Generator field driver (-)
- Generator field driver (+)
- Governor pressure (VFS solenoid)
- Intake manifold air heater relays #1 and #2 control circuits
- CAN C BUS (±) circuits for: speedometer, voltmeter, fuel gauge, oil pressure gauge/lamp, engine temp. gauge and speed control warn. lamp
- Malfunction indicator lamp (Check engine lamp). Driven through J1850 circuits.
- Oil pressure switch/warning lamp (databus)
- Overdrive/3-4 shift solenoid (automatic transmission only)
- SC source
- SCI datalink bus (+) circuits
- SCI datalink bus (-) circuits
- Speed control vacuum solenoid
- Speed control vent solenoid
- Tachometer (if equipped). Driven through J1850 circuits.
- TCC solenoid (automatic transmission only)
- Transmission battery relay (automatic transmission only)
- Transmission throttle valve actuator (automatic transmission only)
- Transmission governor solenoid (automatic transmission only)
- Wait-to-start warning lamp (databus)
- Turbo wastegate solenoid
- Water-In-Fuel (WIF) warning lamp (databus)