P0108

P0108-MANIFOLD ABSOLUTE PRESSURE SENSOR CIRCUIT HIGH





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

Theory of Operation

The Charge 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 Powertrain Control Module (PCM) provides a 5-Volt supply and sensor ground for the Boost Pressure Sensor. The Boost Pressure Sensor provides a signal back to the PCM on the Boost Pressure Sensor Signal circuit. The PCM will detect a low signal voltage at operating conditions such as during an idle or a deceleration. The PCM will detect a high signal voltage during high engine load operating conditions. The PCM 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 PCM estimates the Boost Pressure Sensor value using other fuel system related inputs. The PCM 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 PCM uses an estimated boost pressure reading. The PCM turns off the MIL when the diagnostic runs and passes in four 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 75 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. CHECK THE (K37) BOOST PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE




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 (K37) Boost Pressure Sensor Signal circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 3

3. CHECK FOR THE (K37) BOOST PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO THE (F857) 5-VOLT SUPPLY CIRCUIT




1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between the (K37) Boost Pressure Sensor Signal circuit and (F857) 5-Volt Supply circuit at the Boost Pressure Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K37) Boost Pressure Sensor Signal circuit and (F857) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. CHECK THE (K916) BOOST PRESSURE SENSOR RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE




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

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the (K916) Boost Pressure Sensor Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. CHECK THE BOOST PRESSURE SENSOR
1. Reconnect the Boost Pressure Sensor harness connector.
2. Reconnect the PCM C1 harness connector.
3. Turn the ignition on.
4. With the scan tool, erase DTCs.
5. Turn the ignition off and disconnect the Boost Pressure Sensor harness connector.
6. Turn the ignition on.
7. 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 Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.