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  • P0049 Turbocharger Turbine Overspeed

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    P0049 Turbocharger Turbine Overspeed

    Theory of Operation

    The Turbocharger Speed Sensor is a variable reluctance speed sensor. It consists of a coil of wire and an iron core. The target on the turbocharger shaft is a ground flat surface in the center of the shaft. As the flat surface on the turbocharger shaft spins past the speed sensor, a signal is generated. The Powertrain Control Module (PCM) interprets this signal and converts it to a turbocharger speed reading. The PCM will illuminate the MIL lamp after the diagnostic runs and fails in two consecutive drive cycles. During this time the PCM uses an estimated turbocharger speed. An engine power derate may be experienced. The PCM turns off the MIL when the diagnostic runs and passes in four consecutive drive cycles.

    When Monitored and Set Conditions

    When Monitored: This diagnostic runs continuously when the following conditions are met:

    • With the engine running.

    PCM detects a valid turbocharger speed.

     

    Set Conditions:

    • The PCM detects that the Turbocharger Speed Sensor is out of range.

     

    Default Actions:

    • The MIL will illuminate.

     

    Possible Causes

    • TURBO SPEED SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
    • TURBO SPEED SENSOR SIGNAL CIRCUIT OPEN/HIGH RESISTANCE
    • TURBO SPEED SENSOR RETURN CIRCUIT OPEN/HIGH RESISTANCE
    • TURBOCHARGER SPEED SENSOR

    Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTCBased Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    1. OTHER DTCS

    1. With the scan tool, read DTCs.

     

    Are any DTCs present for Inlet Air Pressure Sensor or Boost Pressure Sensor?

     

    Yes
    • Troubleshoot other DTCs first.
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based
    Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    No
    • Go To 2

     

    2. INTERMITTENT CONDITION
    1. Start the engine.
    2. Using the accelerator pedal, accelerate the engine speed to high idle and hold the engine speed at high
    idle for at least 20 seconds.
    Does DTC P0049 become active?

     

    Yes
    • Go To 3

     

    No
    • Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based
    Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    3. TURBOCHARGER SPEED SENSOR
    1. Turn Ignition off.
    2. Disconnect the Turbocharger Speed Sensor connector. NOTE: Check connectors - Clean/repair as necessary.
    3. Measure the resistance across the (K540) Turbocharger Speed Sensor Signal circuit and the (K541) Turbocharger Speed Sensor Return circuit at the Turbocharger Speed Sensor. Is the resistance between 600 and 1600 Ohms?

     

    Yes

    • Go To 4

     

    No
    • Replace the Turbocharger Speed Sensor in accordance with the Service Information.(Refer to 09 - Engine, 6.7L Diesel/Turbocharger System/SENSOR, Turbocharger Speed/Removal)
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    4. CHECK THE (K540) TURBO SPEED SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
    1. Measure the resistance between ground and the
    (K540) Turbocharger Speed Sensor Signal circuit at the Turbocharger Speed Sensor connector. Is the resistance greater than 10k Ohms?

     

    Yes
    • Go To 5

     

    No
    • Repair the (K540) Turbocharger Speed Sensor Signal circuit for a short to ground.
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    5. CHECK THE (K540) TURBO SPEED SENSOR SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
    1. Disconnect the PCM C1 harness connector.
    NOTE: Check connectors - Clean/repair as necessary.
    2. Measure the resistance of the (K540) Turbocharger Speed Sensor Signal circuit between the Turbocharger Speed Sensor harness connector and the PCM C1 harness connector. Is the resistance below 5.0 Ohms?

     

    Yes
    • Go To 6

     

    No
    • Repair the (K540) Turbocharger Speed Sensor Signal circuit for an open or high resistance.

    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    6. CHECK THE (K541) TURBO SPEED SENSOR RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
    1. Measure the resistance of the (K541) Turbocharger Speed Sensor Return circuit between the Turbocharger Speed Sensor harness connector and the PCM C1 harness connector. Is the resistance below 5.0 Ohms?

     

    Yes
    • Go To 7

     

    No
    • Repair the (K541) Turbocharger Speed Sensor Return circuit for an open or high resistance.
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    7. POWERTRAIN CONTROL MODULE
    1. Disconnect all PCM harness connectors.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
    • Proper connector installation.
    • Damaged connector locks.
    • Corrosion.
    • Other signs of water intrusion.
    • Weather seal damage (if equipped).
    • Bent terminals.
    • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
    • Terminals that have been pushed back into the connector cavity.
    • Perform a terminal drag test on each connector terminal to verify proper terminal tension. Repair any conditions that are found.

     

    5. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. With the scan tool, erase DTCs. 

    9. Using the recorded Freeze Frame and Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    10. With the scan tool, read PCM DTCs. Did the DTC return?

     

    Yes
    • Replace the Powertrain Control Module (PCM) in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control/Removal) .
    • Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    No
    • Test complete.
    • Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


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