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 MANUALSJEEP2009GRAND CHEROKEE LIMITED, 4.7 P, 4WDREPAIR AND DIAGNOSISTRANSMISSIONAUTOMATIC TRANSTRANSMISSION CONTROL MODULE (TCM) - ELECTRICAL DIAGNOSTICSDTC TROUBLESHOOTINGU0424-IMPLAUSIBLE DATA RECEIVED FROM HVAC CONTROL MODULEDIAGNOSTIC TEST
2009 Jeep Grand Cherokee Limited, 4.7 P, 4WD
Diagnostic Test
2009 Jeep Grand Cherokee Limited, 4.7 P, 4WDSECTION Diagnostic Test
- CHECK FOR FCM CAN BUS DTCS
- With the scan tool, read FCM DTCs.
Are there any FCM CAN BUS DTCs present?
Yes
- Refer to DTC Based Diagnostics and perform the appropriate diagnostic procedure.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure
No
- Go to step 2
- With the scan tool, read FCM DTCs.
- CHECK IF HVAC DTCS ARE PRESENT
- With the scan tool, read HVAC DTCs.
Are there any HVAC DTCs present?
Yes
- Refer to DTC Based Diagnostics and perform the appropriate diagnostic procedure.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure
No
- Using the schematics as a guide, check the Transmission Control Module (TCM) 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 and program the TCM in accordance with the Service Information.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - Standard Procedure
- With the scan tool, read HVAC 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.