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Home >> Chrysler >> 2009 >> 300 Signature Series >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> (HVAC Systems (MTC) - Electrical Diagnostics) >> DTC Troubleshooting >> DTC 77: EBL Output Shorted High >> Diagnostic Test

Diagnostic Test

  1. CHECK FOR A SHORTED EBL RELAY 
    Fig 1: Checking For A Shorted EBL Relay
    GC0096339Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Install a known good relay in place of the EBL relay.
    3. Turn the ignition on.
    4. Actuate the Clear DTC function by performing the following:
      • Turn the blower control on.
      • Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.
      • When the A/C status indicator begins displaying DTCs, set the Mode switch to the floor position, simultaneously press the A/C mode switch and the EBL mode switch down until both LEDs start flashing (approximately 5 seconds) and then release the mode switches. Stored DTCs will clear from memory in approximately two seconds.
    5. Press the EBL mode switch on.
    6. Actuate the Display DTC function by performing the following:
      • Turn the blower control on.
      • Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.
      NOTE: The A/C status indicator displays active DTCs when the EBL status indictor is not illuminated and stored DTCs when the EBL status indicator is illuminated.
    7. Read DTCs from the A/C status indictor.

      Does the A/C status indicator display DTC 77?

      Yes 

      • Go to step  2

      No 

  2. CHECK THE (C115) DEFOGGER RELAY CONTROL CIRCUIT FOR A SHORT TO BATTERY 
    Fig 2: Checking Defogger Relay Control Circuit For A Short To Battery
    GC0096416Courtesy of CHRYSLER LLC
    1. Turn the ignition off.
    2. Remove the replacement EBL relay.
    3. Disconnect the A/C Heater Control C1 harness connector.
    4. Turn the ignition on.
    5. Measure the voltage of the (C115) Defogger Relay Control circuit.

      Is the voltage above 0.2 volts?

      Yes 

      No