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 MANUALSJEEP2009COMMANDER SPORT, 3.7 K, RWDREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTCOMMUNICATION DEVICESPASSENGER DOOR MODULE (PDM) - ELECTRICAL DIAGNOSTICSDTC TROUBLESHOOTINGU1000-CAN B BUS (+) CIRCUITDIAGNOSTIC TEST
2009 Jeep Commander Sport, 3.7 K, RWD
Diagnostic Test
2009 Jeep Commander Sport, 3.7 K, RWDSECTION Diagnostic Test
- CHECK FOR ACTIVE DTCS
- With the scan tool, read the active DTCs.
- Cycle the ignition switch from off to on at least 5 times, leaving the ignition on for a minimum of 90 seconds per cycle.
- With the scan tool, read the active DTCs.
Does the scan tool display this DTC as active?
Yes
- Go to step 2
No
- If the DTC is stored, check for an intermittent condition. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.
- CHECK FRONT CONTROL MODULE DTCs
- With the scan tool, read Front Control Module active DTCs
Does the scan tool display any CAN B BUS DTCs - ACTIVE?
Yes
- Perform the appropriate test.
- Refer to DTC-Based Diagnostics/MODULE, Front Control (FCM) - Diagnosis and Testing
No
- Go to step 3
- With the scan tool, read Front Control Module active DTCs
- (D55) CAN B BUS (+) CIRCUIT OPEN
- Turn the ignition off.
- Disconnect the negative battery cable.
- Disconnect the Passenger Door Module C2 connector.
- Disconnect the Front Control Module C1 connector.
- Measure the resistance of the (D55) CAN B Bus (+) circuit between the Front Control Module C1 connector and the Door Module C2 connector.
Is the resistance below 2.0 ohms?
Yes
- Replace the Passenger Door Module in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Repair the (D55) CAN B Bus (+) circuit for an open.
- Perform the BODY VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
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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.