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Home >> Chrysler >> 2011 >> 300 C, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 952 (5.7L CNG - DTCS P0606 To P2123 - 2500 Hd) >> Diagnosis And Testing >> P1655-Alternative Fuel Rail/System Temperature - Too Low >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2015 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. LOW COOLANT LEVEL 
    1. Check the coolant level and operation.

      Is the cooling system operating properly and at the proper level?

      Yes 

      • Go To  2

      No 

  2. HIGH RESISTANCE IN THE CNG RAIL TEMPERATURE SENSOR CIRCUITS 
    NOTE:

    Extremely high ambient temperatures could cause this DTC to set.

    1. Turn the ignition off.
    2. Disconnect the Fuel Rail Sensor harness connector.
    3. Disconnect the PCM C2 harness connector.
      CAUTION:

      Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.

    4. Connect the (special tool #10436, Adapter, GPEC Diagnostic).
    5. Measure the resistance of the:
      • (K163) CNG Rail Temperature Sensor circuit between the Fuel Rail Sensor harness connector and the GPEC Adaptor.
      • (K900) Sensor Return circuit between the Fuel Rail Sensor harness connector and the GPEC Adaptor.

      Is the resistance below 5.0 Ohms for both circuits?

      Yes 

      • Go To  3

      No 

  3. CNG RAIL SENSOR 
    1. Replace the CNG Rail Sensor in accordance with the service information.
    2. Reconnect the PCM C2 harness connector.
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs.
    5. Start the engine and test drive the vehicle in CNG fuel mode.
    6. With the scan tool, view DTCs

      Did the DTC return?

      Yes 

      • Go To  4

      No 

  4. POWERTRAIN CONTROL MODULE (PCM) 
    1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the CNG Rail Sensor and the Powertrain Control Module (PCM).
    2. Look for any chafed, pierced, pinched, or partially broken wires.
    3. Look for broken, bent, pushed out or corroded terminals.
    4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
    5. Look for the data to change or for the DTC to reset during the wiggle test.
    6. Perform any Technical Service Bulletins that may apply.

      Were any problems found?

      Yes 

      No