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 LIMITED, 4.7 P, 4WDREPAIR AND DIAGNOSISENGINE PERFORMANCETUNE-UPFRONT CONTROL MODULE (FCM) - ELECTRICAL DIAGNOSTICSDTC TROUBLESHOOTINGB1668-REVERSE LAMP CONTROL CIRCUIT HIGHDIAGNOSTIC TEST

2009 Jeep Commander Limited, 4.7 P, 4WD

Diagnostic Test

2009 Jeep Commander Limited, 4.7 P, 4WDSECTION Diagnostic Test

TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.
2. Clear all FCM DTC's.
3. Shift the transmission into reverse.
4. With the scan tool, read DTC's.
  Does the scan tool read: B1668-REVERSE LAMP CONTROL CIRCUIT HIGH?
  
  Yes
  - Go to step 2
  No
  - The conditions that caused this code to set are not present at this time. Using the SYSTEM WIRING DIAGRAMS as a guide, inspect the wiring and connectors.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure
(L1) BACK-UP LAMP FEED CIRCUIT SHORT TO VOLTAGE

Fig 1: Checking Back-Up Lamp Feed Circuit Short To Voltage
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the IPM C2 harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (L1) Back-up Lamp Feed circuit.
  Is the voltage greater than 10.0 volts?
  
  Yes
  - Repair the (L1) Back-up Lamp Feed circuit for a short to voltage.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure
  No
  - Replace the IPM in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure

RENDER: 1.0x

NO RELATED

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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.