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 TROUBLESHOOTINGB2122-IGNITION RUN CONTROL 1 CIRCUIT LOWDIAGNOSTIC TEST
2010 Jeep Grand Cherokee Limited, 5.7 T, 4WD
Diagnostic Test
2010 Jeep Grand Cherokee Limited, 5.7 T, 4WDSECTION Diagnostic Test
- CHECK FOR ACTIVE DTC
- With the scan tool, read the active DTCs.
- Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 90 seconds.
- 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.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- LEFT TRAILER TOW RELAY
- Turn the ignition off.
- Install a substitute relay in place of the original Left Trailer Tow Relay.
- Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 90 seconds.
- With the scan tool, read the active FCM DTCs.
Does the scan tool display this DTC as active?
Yes
- Replace the FCM in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
No
- Replace the original Left Trailer Tow Relay.
- Perform the BODY VERIFICATION TEST. See 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.