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Home >> Chrysler >> 2011 >> 300 C, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 603 (3.0L Diesel - DTCS P2455-00 To U1489-00 - 1500) >> Diagnosis And Testing >> U0120-00-Lost Communication With Starter/Generator Control Module >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2014 RAM 1500. However, it is still accessible from the selected car via links, so may be relevant.
  1. DTC IS ACTIVE 
    1. Ignition on, engine not running.
    2. With the scan tool, erase DTCs in the PCM.
    3. Start the engine.
    4. Allow the engine to reach normal operating temperature.
    5. With the scan tool, select View DTCs.

      Is the status Active for this DTC?

      Yes 

      • Go To  2

      No 

  2. GLOW PLUG MODULE 
    1. Turn the ignition off.
    2. Unplug the Glow Plug Module.
    3. Turn the ignition on.
    4. With the scan tool, select View DTCs.

      Did the DTC remain active?

      Yes 

      • Go To  3

      No 

      • Replace the Glow Plug Module in accordance with the service information.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .
  3. CHECK THE (D509) LIN BUS CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Turn the ignition off.
    2. Disconnect the Generator C2 harness connector.
    3. Disconnect the PCM C1 harness connector.
    4. Remove the ASD Relay.
    5. Connect a jumper between terminal 30 and terminal 87.
    6. Turn the ignition on.
    7. Measure the voltage of the (D509) LIN BUS circuit at the Generator C2 harness connector.

      Is there any voltage present?

      Yes 

      • Repair the (D509) LIN BUS circuit for a short to voltage.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .

      No 

      • Go To  4
  4. CHECK THE (D509) LIN BUS CIRCUIT FOR A SHORT TO GROUND 
    1. Turn the ignition off.
    2. Remove the jumper.
    3. Reinstall the ASD Relay.
    4. Measure the resistance between ground and the (D509) LIN BUS circuit at the Generator C2 harness connector.

      Is the resistance above 10k Ohms?

      Yes 

      • Go To  5

      No 

      • Repair the (D509) LIN BUS circuit for a short to ground.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .
  5. CHECK THE (D509) LIN BUS CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Measure the resistance of the (D509) LIN BUS circuit between the Generator C2 harness connector and the PCM C1 harness connector.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Go To  6

      No 

      • Repair the (D509) LIN BUS circuit for an open or high resistance.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .
  6. GENERATOR 
    1. Replace the Generator in accordance with the service information.
    2. Reconnect the PCM C1 harness connector.
    3. Reconnect the Generator C2 harness connector.
    4. Start the engine.
    5. Allow the engine to reach normal operating temperature.
    6. With the scan tool, select View DTCs.

      Did the DTC return?

      Yes 

      • Go To  7

      No 

  7. POWERTRAIN CONTROL MODULE 
    1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Generator and the Powertrain Control Module.
    2. Look for any chafed, pierced, pinched, or partially broken wires.
    3. Look for broken, bent, pushed out or corroded terminals.
    4. Perform any Technical Service Bulletins that may apply.

      Were any problems found?

      Yes 

      No 

      • Replace the Powertrain Control Module in accordance with the service information. Refer to REMOVAL .
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .
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