P0108 INLET AIR PRESSURE SENSOR VOLTAGE TOO HIGH

When Monitored and Set Condition:

When Monitored: With the ignition on and battery voltage greater than 10.4 volts.
Set Condition: The circuit voltage to the ECM is above a calibrated threshold for a certain period of time.

POSSIBLE CAUSES

• OTHER DTC'S PRESENT
• INLET AIR PRESSURE SENSOR
• INLET AIR PRESSURE SENSOR (K69) SIGNAL CIRCUIT SHORTED TO VOLTAGE
• INLET AIR SENSOR (Y501) 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
• (K69) SIGNAL CIRCUIT SORTED TO (Y501) 5-VOLT SUPPLY
• (Y502) RETURN CIRCUIT OPEN
• ECM
• INTERMITTENT CONDITION

DIAGNOSTIC PROCEDURE

NOTE: Refer to VERIFICATION TESTS for appropriate verification test procedures.

1. Ignition on, engine not running. With the DRBIII®, read DTCs. Do you have multiple DTCs?
   Yes --> Repair other DTCs first. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 2
2. Disconnect the Inlet Air Pressure sensor harness connector. Measure the voltage between the (Y501) 5-volt supply circuit and (Y502) return circuit of the Inlet Air Pressure sensor harness connector. Is the voltage between 4.5 and 5.5 volts?
   Yes --> Go To 3
   No --> Go To 4
3. While monitoring DRBIII®, use a jumper wire to connect the (Y502) Return circuit to the (K69) signal circuit at the Inlet Air Pressure sensor harness connector. Does the DRBIII® show a P0107 Inlet Air Pressure Sensor Low DTC.
   Yes --> Replace the Inlet Air Temperature/Pressure sensor. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 4
4. Disconnect the ECM harness connectors. NOTE: Check connectors - Clean/repair as necessary. Measure the voltage between the (K69) signal circuit of the Inlet Air Pressure sensor connector and battery negative. Is the voltage less than 1 volt?
   Yes --> Go To 5
   No --> Repair or replace short to voltage. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
5. Measure the voltage between the (Y501) 5-volt supply circuit of the sensor connector and battery negative. Is the voltage less than 1 volt?
   Yes --> Go To 6
   No --> Repair the short to voltage or replace the harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
6. Turn the ignition off. Measure the resistance between the (K69) signal circuit and the (Y501) 5-volt supply circuit of the Inlet Air Pressure sensor harness connector. Is the resistance less than 10 Ohms?
   Yes --> Go To 7
   No --> Repair or replace the shorted wiring harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
7. Disconnect the ECM harness connector. Check connectors - Clean/repair as necessary. Measure the resistance between the (Y502) return circuit in the Inlet Air Pressure sensor harness connector with the (Y502) return circuit in the ECM harness connector. Is the resistance less than 10 Ohms?
   Yes --> Go To 8
   No --> Repair or replace the Engine harness. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
8. Install the ECM harness connector. Turn the ignition on. While monitoring DRBIII®, use a jumper wire to connect the (Y501) 5-volt supply circuit with the (K69) signal circuit at the Inlet Air Pressure sensor harness connector. Did DTC P0107 set?
   Yes --> Refer to the SYMPTOM: INTERMITTENT CONDITION Symptom (Diagnostic Procedure). Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Replace the ECM. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).