P0112
P0112-INTAKE AIR TEMPERATURE SENSOR CIRCUIT LOWP0112-Intake Temperature Sensor Circuit Low:
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
With the ignition on and battery voltage greater than 10.4 volts.
SET CONDITION
When the Inlet Air Temp Sensor Signal circuit voltage is less than 0.078 volt for more than 2.8 seconds. One trip failure. Three good trips to clear the MIL.
POSSIBLE CAUSES
- (K21) IAT signal shorted to ground
- (K21) IAT signal shorted to the (K900) sensor ground circuit
- Intake air temperature sensor
- PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. IAT SENSOR VOLTAGE BELOW 0.078 OF A VOLT
Ignition on, engine not running.
With a scan tool, read the IAT voltage.
Q: Is the voltage below 0.078 of a volt?
YES: Go To 2
NO: Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Component Tests and General Diagnostics
Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
2. IAT SENSOR
Turn the ignition off.
Disconnect the IAT Sensor harness connector.
Ignition on, engine not running.
With a scan tool, read IAT voltage.
Q: Is the voltage above 0.05 of a volt?
YES: Replace the Intake Air Temperature Sensor. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 3
3. (K21) IAT SIGNAL 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 4
4. (K21) IAT SIGNAL 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 100 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 5
5. 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. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test