Trubleshoot Engine Control Module (ECM)
Electrically erasable, programmable, read-only memory (EEPROM)
ECM functions
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
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Note: See the Service Text for the ECM installation position.
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ECM maintenance precautions
CO US N F E ID O E F N TS TI M AL GL : F O OR BA T L H
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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.
TSWG0008
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.
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.
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)
ECM and component parts
5. Loosen the installation bolts (nuts) and remove the ECM.
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.
Note: See the Service Text due to the fact that the installation method and position varies depending on the main unit.
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.
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RST-10-04-004EN 7
