Mitsubishi Pick-ups and Montero 1983-1995 Repair Guide

Engine Control Module (ECM) Power Ground



If there is incorrect or incomplete contact of the engine control module's ground line, the engine will not function correctly. Therefore, checking before further diagnosis can save a lot of aggravating time.

To prevent the possibility of permanent ECM damage, the ignition switch must always be OFF when disconnecting power from or reconnecting power to the module. This includes unplugging the ECM connector, disconnecting the negative battery cable, removing the unit fuse or even attempting to jump your dead battery using jumper cables.


See Figures 1 and 2

With the ECM connector unplugged, check for continuity of the ground circuit. Connect terminals 101 and 106 (for 2.4L and 3.0L 12 valve engines) or terminals 13 and 26 (for 3.0L 24 valve or 3.5L engines) to a grounded ohmmeter. There should be continuity between these terminals and the ground, if there is not, the circuit (harness) needs to be repaired or replaced from terminals 101 and 106 to ground or 13 and 26 to ground, depending which applies.

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Fig. Fig. 1: The engine control module connector terminals-2.4L and 3.0L (12 valve) engines

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Fig. Fig. 2: The engine control module connector terminals-3.0L (24 valve) and 3.5L engines


See Figure 3

The ECM is extremely sensitive to electrical and mechanical damage. NEVER touch the connector pins or soldered components on the circuit board in order to prevent possible electrostatic discharge damage to the components. Always wear a wrist grounding strap when handling the ECM.

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Fig. Fig. 3: The Electronic Control Module (ECM) is located under the right-hand side dashboard

Although this particular circuit cannot be removed on its own, the ECM can be removed from the vehicle for easier testing. If any repairs need to be done for this procedure, however, the repairs will be in the harness and not the ECM. The ECM is located under the dashboard on the far right-hand side of the vehicle. It is attached with either 2 or 4 screws, so make sure all screws have been removed before trying to do so, and a harness connector.