P0111
P0111-INTAKE AIR TEMPERATURE SENSOR RATIONALITYP0111 - Intake Air Temperature Sensor Rationality:
Theory of Operation
Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compare them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant, and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational.
WHEN MONITORED
The engine off time is greater than 480 minutes. Ambient Temperature if greater than 4 deg C (38 deg F).
SET CONDITION
After a calibrated amount of cool down time the PCM compares the ECT Sensor, IAT Sensor, and the Ambient Air Temp Sensor values. If the IAT Sensor value is not within 10 deg Cof the other two temperature sensors. Two Trip Fault. Three good trips to turn off the MIL.
POSSIBLE CAUSES
- (K21) IAT signal circuit shorted to battery voltage
- (K21) IAT signal circuit open
- (K900) Sensor ground circuit open
- (K21) IAT signal circuit shorted to ground
- (K21) IAT signal circuit shorted to the (K900) sensor ground circuit
- Intake air temperature sensor
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Q: Is the DTC active at this time?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. (K21) IAT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C2 PCM harness connector.
Disconnect the IAT Sensor harness connector.
NOTE: Visually inspect both the component and the PCM connectors.
Look for damaged, partially broken wires, and backed out or corroded terminals.
Ignition on, engine not running.
Measure the voltage on the (K21) IAT Signal circuit in the IAT Sensor harness connector.
Q: Is the voltage above 0 volts?
YES: Repair the short to battery voltage in the (K21) IAT Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 3
3. IAT SENSOR VOLTAGE ABOVE 4.6 VOLTS
Turn the ignition off.
Connect the C2 PCM harness connector.
Ignition on, engine not running.
With a scan tool, read the IAT voltage.
Q: Is the voltage above 4.6 volts?
YES: Go To 4
NO: Go To 7
4. IAT SENSOR
Connect a jumper wire between the (K21) IAT Signal circuit and the (K900) Sensor ground circuit in the IAT Sensor harness connector.
With a scan tool, read the IAT voltage.
Q: Is the voltage below 1.0 volt with the jumper wire installed?
YES: Replace the IAT Sensor. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 5
NOTE: Remove the jumper wire before continuing.
5. (K21) IAT SIGNAL CIRCUIT OPEN
Turn the ignition off.
Disconnect the C2 PCM harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (K21) IAT Signal circuit from the IAT Sensor harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms?
YES: Go To 6
NO: Repair the open in the (K21) IAT Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
6. (K900) SENSOR GROUND CIRCUIT OPEN
Measure the resistance of the (K900) Sensor ground circuit from the IAT Sensor harness connector to the appropriate terminal of special tool #8815.
Q: Is the resistance below 5.0 ohms?
YES: Go To 9
NO: Repair the open in the (K900) Sensor ground circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
7. (K21) IAT SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the C2 PCM harness connector.
Measure the resistance between ground and the (K21) IAT Signal circuit in the IAT Sensor harness connector.
Q: Is the resistance below 100 ohms?
YES: Repair the short to ground in the (K21) IAT Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 8
8. (K21) IAT SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT
Measure the resistance between the (K21) IAT Signal circuit and the (K900) Sensor ground circuit in the IAT Sensor harness connector.
Q: Is the resistance below 5.0 ohms?
YES: Repair the short between the (K900) Sensor ground circuit and the (K21) IAT Signal circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 9
9. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Q: Were there any problems found?
YES: Repair as necessary. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Replace and program the Powertrain Control Module per Service Information. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test