P0049

P0049-TURBOCHARGER TURBINE OVERSPEED





For a complete wiring diagram Refer to Diagrams/Electrical.

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 in the center of the shaft. As the flat on the turbocharger shaft spins past the speed sensor, a signal is generated. The ECM interprets this signal and converts it to a turbocharger speed reading. If this fault becomes active the ECM will light the MIL light immediately. The ETC lamp will also be illuminated at this time. During this time the ECM uses an estimated turbocharger speed. An engine power derate may be experienced. The ECM turns off the MIL when the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
When the key is on and the ECM detects a valid turbocharger speed.

- Set Condition:
ECM detects turbocharger speed greater than a calibration limit.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. OTHER DTC'S
With the scan tool, read DTC's
Are any DTC's present for Inlet air pressure or boost pressure?

Yes


- Troubleshoot other DTC's first.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Go to 2



2. INTERMITTENT CONDITION
Start the engine.
Using the accelerator pedal, accelerate the engine speed to high idle (100%) and hold the engine speed at high idle for at least 20 seconds
Does DTC P0049 become active?

Yes


- Go To 3


No


- Refer to the INTERMITTENT CONDITION - DIESEL Symptom. Intermittent Condition



3. TURBOCHARGER SPEED SENSOR




Turn Ignition off.
Disconnect the engine harness from the turbocharger speed sensor.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance from the (K540) turbocharger speed signal circuit to the (K54) turbocharger speed return circuit at the sensor.
Is the resistance between 600 and 1600 ohms?

Yes


- Go To 4


No


- Replace the Turbocharger speed sensor.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



4. TURBOCHARGER SPEED SENSOR




Measure the resistance from the (K540) turbocharger speed signal circuit to ground at the turbocharger speed sensor connector.
Is the resistance greater than 100k ohms?

Yes


- Go To 5


No


- Replace the Turbocharger speed sensor.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



5. ENGINE HARNESS




Disconnect the ECM harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Reconnect the turbocharger speed sensor connector.
Measure the resistance of the (K540) turbocharger speed sensor signal circuit at the ECM harness connector to the (K54) turbocharger speed sensor return circuit at the ECM harness connector.

NOTE: The resistance of the turbocharger speed sensor circuit must not be more than 10 ohms greater than the resistance of the turbocharger speed sensor. The turbocharger speed sensor resistance value was read in Step 3.

Is the resistance within 10 ohms of the sensor resistance?

Yes


- Go To 6


No


- Repair the high resistance in the engine harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



6. SHORT TO GROUND




Measure the resistance of the (K540) turbocharger speed sensor signal circuit at the ECM harness connector to ground.
Is the resistance greater than 100k ohms?

Yes


- Go To 7


No


- Repair the short to ground.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



7. CIRCUITS SHORTED TOGETHER




Measure the resistance of the (K540) turbocharger speed sensor signal circuit in the ECM harness connector to all other circuits in the ECM harness connector except the (K54) turbocharger speed sensor return circuit.
Is the resistance greater than 100k ohms?

Yes


- Go To 8


No


- Repair the short circuit in the ECM harness connector.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



8. ECM
Reconnect ECM harness connectors.
Start the engine.
Allow the engine to idle
Using the accelerator pedal, accelerate the engine speed to high idle (100%) and hold the engine speed at high idle for at least 20 seconds.
Does DTC P0049 become active?

Yes


- Replace the ECM
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Repair complete.