P051D
P051D-CRANKCASE PRESSURE SENSOR CIRCUIT HIGH
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The crankcase pressure sensor is used to monitor the pressure inside the crankcase. The Powertrain Control Module (PCM) 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 PCM monitors the crankcase pressure signal circuit voltage to calculate the pressure of the air within the crankcase. The PCM 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 PCM 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
- Perform the INTERMITTENT CONDITION - 6.7L diagnostic procedure. Intermittent Condition Test
3. CHECK THE (F857) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the Crankcase Pressure Sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Turn the ignition on.
4. Measure the voltage on the (F857) 5-Volt Supply circuit at the Crankcase Pressure Sensor harness connector.
Is the voltage reading above 5.1 Volts?
Yes
- Repair the (F857) 5-Volt Supply circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 4
4. CHECK THE (K926) CRANKCASE PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Turn the ignition on.
4. Measure the voltage on the (K926) Crankcase Pressure Sensor Signal circuit at the Crankcase Pressure Sensor harness connector.
Is there any voltage present?
Yes
- Repair the (K926) Crankcase Pressure Sensor Signal circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 5
5. CHECK FOR THE (K926) CRANKCASE PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO THE (F857) 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Measure the resistance between the (K926) Crankcase Pressure Sensor Signal circuit and the (F857) 5-Volt Supply circuit at the Crankcase Pressure Sensor harness connector.
Is the resistance above 10k Ohms?
Yes
- Go To 6
No
- Repair the short between the (K926) Crankcase Pressure Sensor Signal circuit and the (F855) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
6. CHECK THE (K916) SENSOR RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K916) Sensor Return circuit between the Crankcase Pressure Sensor harness connector and the PCM C1 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 7
No
- Repair the (K916) Sensor Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
7. CHECK THE CRANKCASE PRESSURE SENSOR
1. Reconnect the PCM harness connectors.
2. Turn the ignition on.
3. While monitoring the scan tool, use a jumper wire to connect the (K916) Sensor Return circuit to 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
- Replace the Crankcase Pressure Sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.