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P0108






P0108-MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT HIGH





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

Theory of Operation

The Air Cooler Temperature Sensor (CAC) and the Boost Pressure Sensor are combined in one sensor and are located near the EGR Airflow Throttle Control Valve. The boost pressure sensor is used to measure pressure in the intake manifold. The Engine Control Module (ECM) provides a 5-volt supply and sensor ground for the Boost Pressure Sensor. The Boost Pressure Sensor provides a signal back to the ECM on the Boost Pressure Sensor Signal circuit. The ECM will detect a low signal voltage at operating conditions such as during an idle or a deceleration. The ECM will detect a high signal voltage during high engine load operating conditions. The ECM performs a key on check and a rationality check. At key ON, the readings for the boost pressure, exhaust gas pressure, and barometric pressure are compared. This fault code occurs if the boost pressure reading is different from the other two. This diagnostic is run five seconds after key on. During normal engine operation, the ECM estimates the Boost Pressure Sensor value using other fuel system related inputs. The ECM compares the actual Boost Pressure Sensor reading to this estimated value.If the two values are out of range for a calibrated period of time, an error is recorded. The key-on portion of the rationality will light the MIL immediately after the diagnostic runs and fails.The rationality portion will light the MIL immediately and the ETC lamp will also be illuminated. During this time the ECM uses an estimated boost pressure reading. The ECM turns off the MIL when the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.

- Set Condition:
The (K37) Boost Pressure Sensor Signal circuit is above 4.75 volts for five seconds.





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

1. ACTIVE DTC

NOTE: If there are any 5-volt supply DTCs present, repair those DTCs before proceeding.

1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition Test.

2. (K37) BOOST PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY




1. Turn the ignition off.
2. Disconnect the Boost Pressure Sensor harness connector.
3. Turn the ignition on.
4. With a voltmeter, measure the voltage of the (K37) Boost Pressure Sensor Signal circuit at the Boost Pressure Sensor harness connector.

Is the voltage reading near battery voltage?

Yes

- Repair the short to battery in the (K37) Boost Pressure Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 3

3. (K37) BOOST PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO (F855) 5-VOLT SUPPLY CIRCUIT




1. Turn the ignition off.
2. Disconnect the ECM C1 harness connector.
3. Measure the resistance between the (K37) Boost Pressure Sensor Signal circuit and (F855) 5-Volt Supply circuit at the Boost Pressure Sensor harness connector.

Is the resistance below 10k ohms?

Yes

- Go To 4

No

- Repair the short between the (K37) Boost Pressure Sensor Signal circuit and (F855) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. (K916) BOOST PRESSURE SENSOR RETURN CIRCUIT OPEN




1. Measure the resistance of the (K916) Boost Pressure Sensor Return circuit between the Boost Pressure Sensor and the ECM C1 harness connectors.

Is the resistance below 10.0 ohms?

Yes

- Go To 4

No

- Repair the open in the (K916) Boost Pressure Sensor Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. BOOST PRESSURE SENSOR
1. Reconnect the Boost Pressure Sensor harness connector.
2. Reconnect the ECM C1 harness connector.
3. Turn the ignition on.
4. Turn the ignition off and disconnect the Boost Pressure Sensor harness connector.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC P0107 set?

Yes

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

No

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

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