P0112
P0112-INTAKE AIR TEMPERATURE (IAT) SENSOR VOLTAGE TOO LOWP0112 - Intake Air Temperature (IAT) Sensor Voltage Too Low:
WHEN MONITORED
With the ignition on and battery voltage greater than 10.4 volts.
SET CONDITION
The circuit voltage to the ECM falls below a calibrated threshold for a certain period of time.
POSSIBLE CAUSES
- Intake air temp sensor out of spec
- Intermittent condition
- (K21) Sensor signal circuit shorted to ground circuit
- Wiring harness shorted
- (F855) 5-Volt supply circuit open
- ECM
- ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
1. INTAKE AIR TEMP SENSOR OUT OF SPEC
Disconnect the Intake Air Temperature sensor harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance of the Intake Air Temp sensor.
Q: Is the resistance between 300 and 90k ohms?
YES: Go To 2
NO: Replace the Intake Air temperature sensor/MAP sensor. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
2. INTERMITTENT CONDITION
Reconnect the circuit.
Turn the ignition on.
With the scan tool, erase DTCs.
With the scan tool, read DTCs.
Q: Did the DTC reappear?
YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 3
3. (K21) SIGNAL CIRCUIT SHORTED TO GROUND CIRCUIT
Turn the ignition off.
Disconnect the ECM harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance between the engine ground and the temperature sensor (K21) signal circuit at the sensor harness connector.
Q: Is the resistance more than 100 k ohms?
YES: Go To 4
NO: Repair or replace the engine wiring harness. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
4. WIRING HARNESS SHORTED
Measure the resistance between the (K21) signal circuit and all other circuits at the ECM harness connector.
Q: Is the resistance more than 100 k ohms?
YES: Go To 5
NO: Repair or replace the shorted wiring harness. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
5. (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO (k916) RETURN CIRCUIT
Reconnect the ECM harness connector connected.
Turn the ignition on.
Measure the voltage between the (F855) 5-volt supply circuit and the (K916) return circuit the sensor harness connector.
Q: Is the voltage between 4.5 and 5.5 volts?
YES: Go To 7
NO: Go To 6
6. (F855) 5-VOLT SUPPLY CIRCUIT OPEN
Turn the ignition off.
Disconnect the ECM harness connector.
Measure the voltage at the (F855) 5-volt supply circuit of the sensor harness connector.
Q: Is the voltage between 4.5 and 5.5 volts?
YES: Repair the open (F855) 5-volt supply circuit. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 7
7. ECM
Reconnect the ECM harness connector.
Reconnect the intake air temp sensor harness connector.
Turn the ignition on.
While monitoring with scan tool, disconnect the temperature sensor
Q: Did the DTC P0113 set?
YES: Clear DTC's, repair complete. 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