P0073
P0073-INLET AIR TEMP SENSOR VOLTAGE TOO HIGHP0073 - Inlet Air Temp Sensor Voltage Too High:
WHEN MONITORED
With 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
- DTC returns
- Inlet air temperature sensor
- (K69) Signal circuit open
- (Y502) Return circuit open
- (K69) Signal circuit shorted
- Intermittent condition
- ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. DTC RETURNS
Turn the ignition on.
With the scan tool, erase DTCs.
With the scan tool, read DTCs.
With the scan tool, record all Freeze frame data.
Q: Did the DTC return?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure).
2. INLET AIR TEMPERATURE SENSOR
Turn the ignition off.
Disconnect the Inlet Air Temp sensor harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance of the Inlet Air temp sensor
Q: Is the resistance between 300 and 90k ohms?
YES: Go To 3
NO: Replace the Inlet air temperature sensor. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1 .
3. RESISTANCE CHECK
Disconnect the ECM harness connector.
Check connectors - Clean/repair as necessary.
Reconnect the Inlet Air Temp sensor harness connector.
Measure the resistance between the (K615) inlet air temperature sensor signal circuit and (K690) return circuit at the ECM connector.
Q: Is the resistance between 300 and 90k ohms?
YES: Go To 6
NO: Go To 4
4. (K615) INLET AIR TEMPERATURE SIGNAL CIRCUIT OPEN
Disconnect the inlet Air Temp sensor harness connector.
Measure the resistance of the (K615) inlet air temperature sensor signal circuit between the sensor harness connector and the ECM harness connector.
Q: Is the resistance less than 10 Ohms?
YES: Go To 5
NO: Repair or replace the harness. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
5. (K690) RETURN CIRCUIT OPEN
Measure the resistance of the sensor (K690) return circuit between the sensor harness connector and the ECM harness connector.
Q: Is the resistance less than 10 Ohms?
YES: Go To 6
NO: Repair or replace the harness. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
6. (K615) SIGNAL CIRCUIT SHORTED
Check for a short circuit from the (K615) signal circuit to all other circuits at the ECM harness connector.
Q: Is the resistance more than 100 k ohms?
YES: Go To 7
NO: Repair or replace the harness for a short to ground in the signal circuit. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
7. ECM
Reconnect the ECM harness connector.
Turn the ignition on.
With the scan tool, erase DTCs.
While monitoring with scan tool, use a jumper wire and connect the sensor (K615) signal circuit to the sensor (K690) return circuit at the sensor connector.
Q: Did the DTC P0072 set?
YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Replace the ECM. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1