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Home >> Jeep >> 2018 >> Grand Cherokee Laredo, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 9 (3.0L Diesel - DTCS P1693-00 To P2200-00) >> DTC Troubleshooting >> P20BD-00-REDUCTANT Pressure Line Heater Control Circuit/Open >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR AN ACTIVE DTC 
    1. Ignition on, engine not running.
    2. With the scan tool, erase DTCs in the PCM.
    3. Start the engine and allow the engine to reach normal operating temperature.
    4. Monitor the scan tool for at least two minutes.
    5. With the scan tool, select View DTCs.

      Is the status Active for this DTC?

      Yes 

      • Go To  2

      No 

      • Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT DTC .
  2. CHECK THE (K404) DEF LINE HEATER SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Disconnect the DEF Line Heater harness connector.
    3. Disconnect the HCU harness connector.
    4. Measure the resistance of the (K404) DEF Line Heater Supply circuit between the DEF Line Heater harness connector and the HCU harness connector.

      Is the resistance above 5.0 Ohms?

      Yes 

      • Repair the (K404) DEF Line Heater Supply circuit for an open or high resistance.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECK THE (K404) DEF LINE HEATER SUPPLY CIRCUIT FOR A SHORT TO GROUND 
    1. Measure the resistance between ground and the (K404) DEF Line Heater Supply circuit at the DEF Tank Heater harness connector.

      Is the resistance above 10k Ohms?

      Yes 

      • Go To  4

      No 

      • Repair the (K404) DEF Line Heater Supply circuit for a short to ground.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .
  4. CHECK THE DEF LINE HEATER ASSEMBLY FOR PROPER OPERATION 
    1. Replace the DEF Line Heater Assembly in accordance with the service information.
    2. Reconnect the DEF Line Heater harness connector.
    3. Reconnect the HCU harness connector.
    4. Ignition on, engine not running.
    5. With the scan tool, erase DTCs in the PCM.
    6. Start the engine.
    7. Allow the engine to reach normal operating temperature.
    8. Monitor the scan tool for at least two minutes.
    9. With the scan tool, select View DTCs.

      Is the status Active for this DTC?

      Yes 

      • Replace the Heater Control Unit (HCU) in accordance with the service information.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .

      No 

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