P051D

P051D-CRANKCASE PRESSURE SENSOR CIRCUIT HIGH





For a complete wiring diagram refer to the Wiring Information Electrical Diagrams. Electrical Diagrams

Theory of Operation

The crankcase pressure sensor is used to monitor the pressure inside the crankcase. The ECM supplies the crankcase pressure sensor a 5-volt reference voltage. When the crankcase pressure is low, the sensor signal voltage is low. When the crankcase pressure is high, the sensor signal voltage is near the 5-volt reference voltage. The ECM monitors the crankcase pressure signal circuit voltage to calculate the pressure of the air within the crankcase. The ECM does not illuminate the MIL or ETC lamp for any of the crankcase pressure faults.

- When Monitored:
Ignition on, engine not running.

- Set Condition:
The circuit voltage to the ECM is above a calibrated threshold for a certain period of time





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure

1. OTHER DTCS
1. Ignition on, engine not running.
2. With the scan tool, read DTCs.

Are there any 5-volt supply DTCs ?

Yes

- Repair other DTCs first.

No

- Go To 2

2. P051D ACTIVE

Is DTC P051D active?

Yes

- Go To 3

No

- Refer to the INTERMITTENT CONDITION - DIESEL diagnostic procedure.Intermittent Condition Test

3. (F855) 5-VOLT SUPPLY
1. Turn the ignition off.
2. Disconnect the Crankcase pressure sensor harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the voltage between the (F855) 5-volt supply circuit and (K916) Sensor ground circuit of the Crankcase Pressure Sensor harness connector.

Is the voltage between 4.5 and 5.5 volts?

Yes

- Go To 4

No

- Go To 5

4. CRANKCASE PRESSURE SENSOR
1. While monitoring the scan tool, use a jumper wire to connect the (K916) Sensor ground circuit to the (K926) Crankcase Pressure Signal circuit at the Crankcase Pressure Sensor harness connector.

Does the scan tool show a P-051C Crankcase Pressure sensor low DTC?

Yes

- Replace the Crankcase Pressure Sensor.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 5

5. (K926) CRANKCASE PRESSURE SIGNAL CIRCUIT SHORTED VOLTAGE
1. Turn the ignition off.
2. Disconnect the ECM harness connectors.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the voltage between the (K926) Crankcase Pressure Signal circuit of the Crankcase Pressure sensor connector and battery negative.

Is the voltage less than 1 volt?

Yes

- Go To 6

No

- Repair or replace the shorted wiring harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

6. (F855) 5-VOLT SUPPLY SHORTED TO HIGH VOLTAGE
1. Measure the voltage between the (F855) 5-volt supply circuit of the sensor connector and battery negative.

Is the voltage less than 1 volt?

Yes

- Go To 7

No

- Repair or replace the shorted wiring harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L.Powertrain Verification Test

7. (K926) CRANKCASE PRESSURE SIGNAL CIRCUIT SHORTED TO (F855) 5-VOLT SUPPLY
1. Measure the resistance between the (K926) Crankcase Pressure Signal circuit and the (F855) 5-volt supply circuit of the Crankcase Pressure sensor harness connector.

Is the resistance less than 10 ohms?

Yes

- Go To 8

No

- Repair or replace the shorted wiring harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L.Powertrain Verification Test

8. (K916) SENSOR GROUND CIRCUIT OPEN
1. Measure the resistance between the (K916) Sensor ground circuit in the Crankcase Pressure sensor harness connector with the (K916) Sensor ground circuit in the ECM harness connector.
2. Is the resistance less than 10 ohms?

Is the resistance less than 10 ohms?

Yes

- Go To 9

No

- Repair or replace the open wiring harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L.Powertrain Verification Test

9. ECM
1. Reconnect the ECM harness connectors.
2. Ignition on, engine not running.
3. While monitoring scan tool, use a jumper wire to connect the (K916) Sensor ground circuit with the (K926) Crankcase Pressure Signal circuit at the Crankcase Pressure sensor harness connector.

Does the scan tool show a P051C Crankcase Pressure sensor low DTC?

Yes

- Refer to the INTERMITTENT CONDITION - DIESEL diagnostic procedure.Intermittent Condition Test

No

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