Operation - ECM

WARNING: This page is about a different car, the 2004 Dodge Pickup and 2004 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The main function of the Engine Control Module (ECM) is to electrically control the fuel system. The Powertrain Control Module (PCM) does not control the fuel system.

The ECM can adapt its programming to meet changing operating conditions. If the ECM has been replaced, flashed or re-calibrated, the ECM must learn the Accelerator Pedal Position Sensor (APPS) idle voltage. Failure to learn this voltage may result in unnecessary diagnostic trouble codes. Refer to ECM REMOVAL / INSTALLATION for learning procedures.

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) Volts
APPS1 Signal - For off engine APPS
APPS2 Signal - For off engine APPS
APPS idle validation switches #1 and #2
Battery Temperature
Battery voltage
Camshaft Position Sensor (CMP)
CCD bus (+) circuits
CCD bus (-) circuits
Crankshaft Position Sensor (CKP)
Data link connection for DRB scan tool
Engine Coolant Temperature (ECT) sensor
Fuel pressure sensor
Fan speed (engine cooling fan)
Ground circuits
Inlet air temperature sensor/pressure sensor
Intake air temperature sensor/MAP sensor
Oil Pressure switch
Power ground
Sensor return
Signal ground
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:

CCD bus (+) circuits
CCD bus (-) circuits
CKP and APPS outputs to the PCM
Data link connection for DRB scan tool
Fan Clutch PWM
Five volt sensor supply
Fuel Control Actuator
Fuel transfer (lift) pump
Intake manifold air heater relays #1 and #2 control circuits
Malfunction indicator lamp (Check engine lamp) (databus)
Oil Pressure Swith/warning lamp (databus)
Wait-to-start warning lamp (databus)
Water-In-Fuel (WIF) warning lamp (databus)