Engine Control Module (ECM

Engine Control Module (ECM) ECM functions

Note:

See the Service Text for the ECM installation position.

The ECM constantly monitors information sent from the various sensors and controls each system of the powertrain.The ECM implements system function diagnosis, detects problems in system operation, and stores the diagnostic trouble code in memory along with issuing a warning to the operator through the diagnostic lamp.The diagnostic trouble code identifies the area in which the problem occurred and supports repair work by the service engineer. The ECM puts out 5 V and other voltages to supply power to the various sensors and switches.The ECM controls output circuits by controlling ground or power supply circuits via one device or another.

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ECM and component parts

The ECM is designed to provide superior performance and fuel efficiency at the same time it keeps exhaust gas at the regulated level.The ECM monitors various engine functions via sensors such as the crankshaft position (CKP) sensor.

ECM voltage

The ECM applies standard voltage to various switches and sensors.The reason the ECM is able to apply voltage in this way is because of its especially high resistance. The voltage actually applied to the circuit is low and a test light may not illuminate even if connected to the circuit.Due to the voltmeter input impedance normally used at maintenance factories being too low, an accurate reading value may not be displayed.Use a 10 MΩ input impedance digital tester in order to get an accurate voltage reading value.

Electrically erasable, programmable, read-only memory (EEPROM)

The EEPROM contains necessary program and calibration information for the ECM to control powertrain operation. Replace the ECM if a problem is recognized in the EEPROM. ECM powertrain control program and calibration information consists of the following items. • Engine model • Engine number • ECM parts number • Diagnostic trouble code • Learning value for interval correction of cylinders • QR • Q resistance • EGR correction learning value

ECM maintenance precautions

Note:

• Use an ECM with a part number that corresponds to the main unit. • When performing welding on the main unit, be sure to disconnect the negative terminal of the battery before performing welding.

The ECM is designed to withstand the normal current consumption associated with main unit operation.Do not overload the circuit.When performing a test for disconnections and shorts, unless otherwise specified, do not connect the ECM circuit to a ground and do not apply any voltage.When performing these circuit tests, make sure to use a digital tester.

ECM removal

1. Turn the key switch OFF. 2. Disconnect the negative terminal of the battery. 3. To make removal easier, remove parts around the ECM (relay or the like). 4. Remove the ECM connectors from the ECM.(81 pin, 40 pin connectors) 5. Loosen the installation bolts (nuts) and remove the

ECM.

Note:

See the Service Text due to the fact that the installation method and position varies depending on the main unit.

ECM installation

ECM installation is the reverse of the removal procedure. When the ECM has been replaced, make sure to perform EGR valve position learning. 1. Turn the key switch "ON". 2. Turn the key switch OFF. 3. Wait about 10 sec. with the machine in this state. If EGR valve position learning is not performed, an EGR diagnostic trouble code may be detected.

Turning the ECM power OFF

For about 10 sec. after turning the key switch OFF, power within the ECM is not yet turned OFF.When it is necessary to turn the ECM power OFF to perform tasks such as clearing the memory, it is necessary to wait for at least 10 sec. after the key switch is turned OFF.

Key switch ON

Key switch OFF

10 sec

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