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8E - 4
ELECTRONIC CONTROL MODULES
ENGINE CONTROL MODULE
DESCRIPTION - ECM
The Engine Control Module (ECM) is bolted to the
left side of the engine below the intake manifold (Fig.
2).
Fig. 2 DIESEL ECM
1 - ENGINE CONTROL MODULE (ECM)
2 - ECM MOUNTING BOLT
3 - 50-WAY CONNECTOR
4 - SUPPORT PLATE
5 - 60-WAY CONNECTOR
OPERATION - ECM
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 diagnos-
tic trouble codes. Refer to ECM Removal/Instal-
lation 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 compo-
nents 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 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
• Ground circuits
• Fuel Pressure Sensor
• Battery Temperature
• Fan speed
• 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 sen-
sors, switches and components are controlled or reg-
ulated 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
• Five volt sensor supply
• Fuel transfer (lift) pump
• Intake manifold air heater relays #1 and #2 con-
trol circuits
• Malfunction indicator lamp (Check engine lamp)
(databus)
• Oil Pressure Swith/warning lamp (databus)
• Fuel Control Actuator
• Wait-to-start warning lamp (databus)
• Fan Clutch PWM
• Water-In-Fuel (WIF) warning lamp (databus)
REMOVAL
The Engine Control Module (ECM) is bolted to a
support bracket near the fuel filter. The support
bracket mounts to the block with four capscrews and
vibration isolators. A ground wire is fastened to the
bracket. The other end of the wire is fastened to the
engine block.
(1) Record any Diagnostic Trouble Codes (DTC's)
found in the ECM.
DR
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