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 MANUALSJEEP2009PATRIOT LIMITED, EDG, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 4 ((ALL WHEEL DRIVE (AWD) MODULE - ELECTRICAL DIAGNOSTICS))DTC TROUBLESHOOTINGU0100-LOST COMMUNICATION WITH ECM/PCMDIAGNOSTIC TEST
2009 Jeep Patriot Limited, EDG, Standard
Diagnostic Test
2009 Jeep Patriot Limited, EDG, StandardSECTION Diagnostic Test
WARNING: This page is about a different variant/trim than selected.
- VERIFY DTC IS ACTIVE NOTE: For vehicle communication problems, use the scan tool to refer to the Network Review Screen. The screen depicts a high level view of the vehicle network. Fault and problem areas appear in red. Selecting any of the network components allows access to the source of the problem.
- Ignition on, engine off.
- With the scan tool, read the DTCs.
Is this DTC active?
Yes
- Go to step 2
No
- Refer to Non-DTC Diagnostics/Communication - Diagnosis and Testing and perform the Stored Lost Communication DTC diagnostic procedure.
- CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
- With the scan tool, read all active DTCs from all modules.NOTE: Check for TIPM 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
- Refer to DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Diagnosis and Testing 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 Diagnostics.
- 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 Non-DTC Diagnostics/Communication - Diagnosis and Testing and perform the No Response from ECM/PCM diagnostic procedure.
- CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS
- With the scan tool, select Network Diagnostics.
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 appropriate VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure for gas engine applications or. Refer to DTC-Based Diagnostics/MODULE, Engine Control (ECM) - Standard Procedure for diesel engine applications.
No
- Replace/update the module that set this DTC in accordance with the Service Information.
- Perform the AWD VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, All Wheel Drive (AWD) - Standard Procedure .
- With the scan tool, select Network Diagnostics.
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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.