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ECM NON–MONITORED SYSTEMS The ECM does not monitor the following circuits, systems or conditions that could have malfunctions Fuel Pressure: Fuel pressure is controlled by the fuel injection pump. The ECM cannot detect fuel Cylinder Compression: The ECM cannot detect uneven, low, or high engine cylinder compression. Exhaust System: The ECM cannot detect a plugged, restricted or leaking exhaust system. Fuel Injector Malfunctions: The ECM cannot determine if the fuel injector is clogged, or the wrong Vacuum Assist: Leaks or restrictions in the vac- uum circuits of vacuum assisted engine control sys- ECM System Ground: The ECM cannot deter- mine a poor system ground. However, a DTC may be ECM/PCM Connector Engagement: The ECM cannot determine spread or damaged connector pins. HIGH AND LOW LIMITS The ECM compares input signals from each input device. It will establish high and low limits that are DIAGNOSTIC TROUBLE CODES DESCRIPTION On the following pages, a list of DTC’s is provided for the 3.1L diesel engine. A DTC indicates that the ACCESSING DIAGNOSTIC TROUBLE CODES A stored DTC can be displayed through the use of the DRB III t scan tool. The DRB IIIt connects to the data link connector. The data link connector is ERASING TROUBLE CODES After the problem has been repaired, use the DRB III t scan tool to erase a DTC. Fig. 1 Data Link Connector Location — LHD Typical 1 – INSTRUMENT PANEL LOWER/LEFT EDGE 25 - 2 EMISSION CONTROL SYSTEM WJ DESCRIPTION AND OPERATION (Continued) 2000 JEEP GRAND CHEROKEE |