Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSJEEP2010GRAND CHEROKEE LIMITED, 5.7 T, 4WDREPAIR AND DIAGNOSISENGINE PERFORMANCEENGINE CONTROL SYSTEMS(FRONT CONTROL MODULE (FCM) - ELECTRICAL DIAGNOSTICS)DTC TROUBLESHOOTINGU0100-LOST COMMUNICATION WITH ECM/PCMDIAGNOSTIC TEST
2010 Jeep Grand Cherokee Limited, 5.7 T, 4WD
Diagnostic Test
2010 Jeep Grand Cherokee Limited, 5.7 T, 4WDSECTION Diagnostic Test
- VERIFY THE DIAGNOSTIC TROUBLE CODE (DTC) IS ACTIVE NOTE: Ensure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.
- With the scan tool, read active DTCs.
Is this DTC active?
Yes
- Go to step 2
No
- Refer to the Stored Lost Communication test procedure. Refer to Non-DTC Diagnostics/Communication - Diagnosis and Testing
- With the scan tool, read active DTCs.
- CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
- With the scan tool, read all active DTCs from all modules.NOTE: Check for FCM configuration, CAN B or C hardware electrical, VIN Missing/Mismatch, battery or ignition related DTCs.
Does the scan tool display any active DTCs to the conditions listed above?
Yes
- Go to DIAGNOSTIC CODE INDEX table and perform the appropriate diagnostic procedure.
No
- Go to step 3
- With the scan tool, read all active DTCs from all modules.
- VERIFY THAT THE ECM/PCM IS ACTIVE ON THE BUS
- Turn the ignition on.
- With the scan tool, select Network View and select Advanced.
- Verify that the ECM/PCM is active on the bus.
Is the ECM/PCM active on the bus?
Yes
- Go to step 4
No
- Refer to the No Response test procedure. Refer to Non-DTC Diagnostics/Communication - Diagnosis and Testing
- CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS
- With the scan tool, select Network View and select Advanced.
Is there more than one module with active DTCs "Logged Against" the ECM/PCM?
Yes
- Replace/update the ECM/PCM in accordance with the Service Information.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure
No
- Replace/update the module that set this DTC in accordance with the Service Information.
- Perform the appropriate VERIFICATION TEST.
- With the scan tool, select Network View and select Advanced.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.