Trooper II 2.8L V6

The ECM is located under the center console tray. The ECM constantly looks at information from various sensors and controls the systems that affect vehicle performance. The ECM self-diagnostic capabilities allow for trouble shooting the system through a check engine light. The check engine light will illuminate to alert the driver of a system malfunction. The check engine light will display a problem via a 2-digit code displayed by the check engine light.

To allow one model of ECM to be used for many different car models, a device called a Programmable Read Only Memory (PROM) is used. The PROM is located inside the ECM and has information on the vahicle weight, engine, transmission, axle ratio, etc.. While many ECM part numbers can be used by many vehicle models, the PROM can only be used for that vehicle. Therefore, it is extremely important that when replacing the ECM, the PROM be removed from the old ECM and installed in the new ECM.

A device called a CALPAK is also located inside the ECM. The device is used to allow fuel delivery system to keep working if other parts of the ECM are damaged. If the CALPAK is missing, it will result in a no start and run condition. If the ECM is being replaced, the CALPAK must be transferred to the new ECM.