The Engine Control Module (ECM) interacts with many emission related components and systems, and monitors the emission related components and systems for deterioration. OBD II diagnostics monitor the system performance and a Diagnostic Trouble Code (DTC) sets if the system performance degrades.
The ECM is the control center of the engine controls system. The ECM controls the following components:
The ECM constantly monitors the information from various sensors and other inputs, and controls the systems that affect the vehicle performance and the emissions. The ECM also performs diagnostic tests on various parts of the system. The ECM can recognize operational problems and alert the driver via the MIL. When the ECM detects a malfunction, the ECM stores a DTC. The condition area is identified by the particular DTC that is set. This aids the technician in making repairs.
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 megaohms input impedance is required in order to ensure accurate voltage readings.
Removal & Installation
- 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 wiring harness electrical connector from the ECM.
- Disconnect the body wiring harness electrical connector from the ECM.
- Release the retaining tab located on the battery tray 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 battery tray.
- Push down on the ECM until the retaining tab snaps into place.
- Connect the body wiring harness electrical connector to the ECM.
- Connect the engine wiring harness electrical connector to the ECM.
- Connect the negative battery cable.
- Reset the clock and preset radio stations.
- If a new ECM was installed, the ECM must be programmed.
- Observe the DTCs with the scan tool.
- If DTC P0602 is set, attempt to program the Engine Control Module (ECM) before replacing the ECM.
- If DTC P0602 resets, replace the ECM.
Test the voltage and ground circuits to the control module for the following: