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 OVERLAND, 4WDREPAIR AND DIAGNOSISENGINE PERFORMANCEIGNITION SYSTEMFRONT CONTROL MODULE (FCM) - ELECTRICAL DIAGNOSTICSDTC TROUBLESHOOTINGB1634-LEFT HI BEAM CONTROL CIRCUIT HIGHDIAGNOSTIC TEST

2009 Jeep Commander Overland, 4WD

Diagnostic Test

2009 Jeep Commander Overland, 4WDSECTION Diagnostic Test

INTERMITTENT CONDITION
1. Turn the ignition on.
2. Using the scan tool, clear all FCM DTCs.
3. Turn the Headlamps on.
4. With the scan tool read the DTC information.
  Does the scan tool read: B1634-LEFT HI BEAM CONTROL CIRCUIT HIGH?
  
  Yes
  - Go to step 2
  No
  - The condition that caused the symptom is currently not present. Inspect the related wiring for a possible intermittent condition. Look for any chafed, pierced, pinched, or partially broken wires.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
LEFT HIGH BEAM BULB
1. Turn the ignition off.
2. Inspect the Left High Beam Bulb Assembly.
  Is the inoperative bulb OK?
  
  Yes
  - Go to step 3
  No
  - Replace the Inoperative bulb in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
(L33) HIGH BEAM CONTROL CIRCUIT

Fig 1: Checking High Beam Control Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the FCM C2 harness connector.
3. Measure the resistance of the (L33) High Beam Control circuit.
  Is the resistance above 5.0 Ohms?
  
  Yes
  - Repair the (L33) High Beam Control circuit for an open condition.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
  No
  - Replace the Front Control Module (FCM) in accordance with the Service Information.
  - 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.