The Engine Control Module (ECM) can supply 5 volts or 12 volts to the various sensors or switches. This is done through pull-up resistors to the regulated power supplies within the ECM. In some cases, even an ordinary shop voltmeter will not give an accurate reading because the resistance is too low. Therefore, a DMM with at least 10 mega ohms input impedance is required in order to ensure accurate voltage readings.
The ECM controls the output circuits by controlling the ground or the power feed circuit through the transistors or a device called an output driver module.
Removal & Installation
Turn the ignition OFF when installing or removing the Engine Control Module (ECM) connectors and disconnecting or reconnecting the power to the control module (battery cable, Powertrain Control Module (PCM)/engine control module (ECM)/transaxle control module (TCM) pigtail, control module fuse, jumper cables, etc.) in order to prevent internal control module damage.
Control module damage may result when the metal case contacts battery voltage. DO NOT contact the control module metal case with battery voltage when servicing a control module, using battery booster cables, or when charging the vehicle battery.
In order to prevent any possible electrostatic discharge damage to the control module, do no touch the connector pins or the soldered components on the circuit board.
Remove any debris from around the control module connector surfaces before servicing the control module. Inspect the control module connector gaskets when diagnosing or replacing the control module. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the control module.
The replacement control module must be programmed. It is necessary to record the remaining engine oil life. If the replacement module is not programed with the remaining engine oil life, the engine oil life will default to 100 percent. If the replacement module is not programmed with the remaining engine oil life, the engine oil will need to be changed at 5 000 km (3,000 mi) from the last engine oil change.
- Using a scan tool, retrieve the percentage of remaining engine oil. Record the remaining engine oil life.
- Record the preset radio stations.
- Turn the ignition OFF.
- Disconnect the negative battery cable.
- Disconnect the engine control module (ECM) harness connectors.
- Release the retaining tab located in the battery box lower half using a small screwdriver or other suitable tool.
- Remove the ECM by lifting upward after releasing the tab.
- Slide the ECM into the bracket on the front of the battery box.
- Push down on the ECM until the retaining tab snaps into place.
- Connect the ECM harness connectors.
- Connect the negative battery cable tighten to 13 ft. lbs. (17 Nm).
- Reset the clock and preset radio stations.
- If a NEW ECM was installed, the ECM must be programmed.
Test the voltage and ground circuits to the control module for the following:
If all circuits test normal, suspect the ECM.
NOTEThe replacement control module must be programmed.