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 TROUBLESHOOTINGU0401-IMPLAUSIBLE DATA RECEIVED FROM 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.
- CHECK FOR DTC U0401-IMPLAUSIBLE DATA RECEIVED FROM ECM/PCM NOTE: This DTC must be active for the results of this test to be valid.
- Ignition on, engine not running.
- With the scan tool, record and erase DTCs.
- Cycle the ignition switch from off to on.
- With the scan tool, read DTCs.
Does the scan tool display: U0401-IMPLAUSIBLE DATA RECEIVED FROM ECM/PCM?
Yes
- Go to step 2
No
- The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
- Perform the AWD Control Module VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, All Wheel Drive (AWD) - Standard Procedure .
- CHECK IF TIPM CAN BUS DTCs ARE PRESENT
- With the scan tool, read TIPM DTCs.
Are there any TIPM CAN BUS DTCs present?
Yes
- Perform the appropriate symptom. Refer to DTC-Based Diagnostics/MODULE, Totally Integrated Power (TIPM) - Diagnosis and Testing
- Perform AWD Control Module VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, All Wheel Drive (AWD) - Standard Procedure .
No
- Go to step 3
- With the scan tool, read TIPM DTCs.
- CHECK IF ENGINE DTCs ARE PRESENT
- With the scan tool, read Engine DTCs.
Are there any Engine DTCs present?
Yes
- Perform the appropriate symptom. Refer to DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Diagnosis and Testing
- Perform AWD Control Module VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, All Wheel Drive (AWD) - Standard Procedure .
No
- Using the schematics as a guide, check the AWD Control Module pins, terminals, and connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the AWD Control Module in accordance with the Service Information.
- Perform AWD Control Module VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, All Wheel Drive (AWD) - Standard Procedure .
- With the scan tool, read Engine DTCs.
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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.