P0112 - Intake Air Temperature Sensor 1 Circuit
Theory of Operation
The Intake Manifold Temperature (IMT) Sensor is located on the intake manifold on the Regular Cab. For the Cab and Chassis, it is a part of the Temperature/Pressure MAP Sensor. The IMT Sensor is used to measure the temperature of the air in the intake manifold. The Powertrain Control Module (PCM) supplies 5-Volts to the intake manifold temperature signal circuit. The PCM monitors the change in voltage caused by changes in the
resistance of the sensor to determine the intake manifold temperature. The MIL lamp is illuminated immediately when the diagnostic runs and fails. During this time the customer may notice periods of white smoke as well as the fan running more often. The MIL lamp is turned off once the diagnostic runs and passes in four consecutive drive cycles.
When Monitored and Set Conditions
When Monitored: This diagnostic runs continuously when the following conditions are met:
• With the ignition on.
Set Conditions:
• The Powertrain Control Module (PCM) has detected the Intake Manifold Temperature Sensor circuit is
below a calibrated threshold.
Default Actions:
• The MIL is illuminated.
Possible Causes
INTAKE MANIFOLD TEMPERATURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
INTAKE MANIFOLD TEMPERATURE SENSOR SIGNAL CIRCUIT SHORTED TO THE SENSOR
GROUND CIRCUIT
TEMPERATURE/PRESSURE MAP SENSOR
POWERTRAIN CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTCBased Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.
Did the DTC reset?
Yes
• Go To 2
No
• Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
2. CHECK THE INTAKE MANIFOLD TEMPERATURE CIRCUIT
1. Turn the ignition off.
2. Disconnect the T/P MAP sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Measure the resistance from the Sensor ground (K916) to the Intake Manifold Temperature circuit (K21) across the terminals at the T/P MAP sensor harness connector.
Is the resistance between 300 and 90k Ohms?
Yes
• Go To 3
No
• Replace the T/P MAP Sensor in accordance with the service information.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
3. CHECK THE (K21) INTAKE MANIFOLD TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
1.
2. Disconnect the PCM C1 harness connector.
NOTE: Check connectors - Clean/repair as necessary.
3. Measure the resistance between ground and the (K21) Intake Manifold Temperature Signal circuit at the T/P MAP sensor harness connector. Is the resistance below 10k Ohms?
Yes
• Repair the (K21) Intake Manifold Temperature Signal circuit for a short to ground.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Go To 4
4. CHECK FOR THE (K21) INTAKE MANIFOLD TEMPERATURE SIGNAL CIRCUIT SHORTED TO THE (K916) SENSOR GROUND CIRCUIT
1.
2. Measure the resistance between the (K21) Intake Manifold Temperature Signal circuit and the (K916)
Sensor Ground circuit at the T/P MAP sensor harness connector. Is the resistance below 10k Ohms?
Yes
• Repair the short between the (K21) Intake Manifold Temperature Signal circuit and the (K916) Sensor Ground circuit.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Replace the Powertrain Control Module in accordance with the service information.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).