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Home >> Jeep >> 2010 >> Grand Cherokee SRT-8 >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> (Front Control Module (FCM) - Electrical Diagnostics) >> DTC Troubleshooting >> B1668-Reverse Lamp Control Circuit High >> Diagnostic Test
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Diagnostic Test

  1. TEST FOR INTERMITTENT CONDITION 
    1. Turn the ignition on.
    2. With the scan tool, clear all FCM DTCs.
    3. Shift the transmission into reverse.
    4. With the scan tool, read DTCs.

      Does the scan tool display: B1668-REVERSE LAMP CONTROL CIRCUIT HIGH?

      Yes 

      • Go to step  2

      No 

  2. (L1) BACK-UP LAMP FEED CIRCUIT SHORT TO VOLTAGE 
    Fig 1: Checking Back-Up Lamp Feed Circuit Short To Voltage
    GC0120115Courtesy 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 

      No 

      • Go to step  3
  3. CHECK (L1) BACK-UP LAMP FEED CIRCUIT IN IPM FOR A SHORT TO BATTERY VOLTAGE 
    Fig 2: Checking Back-Up Lamp Feed Circuit For A Short To Battery Voltage
    GC0138735Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Disconnect the Front Control Module (FCM) from the IPM 49-way connector.
    3. Reconnect the IPM C2 harness connector.
    4. Measure the voltage between ground and the (L1) Back-up Lamp circuit.

      Is there any voltage present?

      Yes 

      No