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Home >> Jeep >> 2009 >> Commander Overland, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 25 (Electronic Control Modules (Service Information)) >> Electronic Control Modules >> Module-Engine Control >> Operation >> Engine Control Module (ECM) >> ECM Diagnostic Trouble Codes

ECM Diagnostic Trouble Codes

WARNING: This page is about a different car, the 2008 Jeep Commander. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT NOTE: Before replacing the ECM for a failed driver, control circuit or ground circuit, be sure to check the related component/circuit integrity for failures not detected due to a double fault in the circuit. Most ECM driver/control circuit failures are caused by internal failures to components (i.e. relays and solenoids) and shorted circuits (i.e. sensor pull-ups, drivers and ground circuits). These faults are difficult to detect when a double fault has occurred and only one DTC has set. If the scan tool displays faults for multiple components (i.e.VSS, ECT, Batt Temp, etc.) identify and check the shared circuits for possible problems before continuing (i.e. sensor grounds or 5-volt supply circuits). Refer to the SYSTEM WIRING DIAGRAMS article to identify shared circuits. Refer to appropriate diagnostic information.