Circuit DescriptionThe intake manifold 1 temperature sensor is a variable resistor sensor and is used to measure the temperature of the air entering the intake manifold of the engine. The engine intake manifold temperature value is used by the engine control module (ECM) for the engine protection system and engine emission control.
The ECM supplies 5 volts to the intake manifold temperature signal circuit and monitors the change in voltage caused by changes in the resistance of the sensor to determine the intake manifold temperature. When the intake air is cold, the sensor (or thermistor) resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to a ground. Therefore, the ECM senses a high signal voltage or low temperature. When the intake air is warm, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage or high temperature.
Component LocationThe engine intake manifold temperature sensor is located in the air intake manifold.
Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position.
Conditions for Setting the Fault CodesThe ECM detects that the intake manfiold air temperature is greater than 132?C [270?F] for 5 seconds.
Action Taken When the Fault Code is ActiveThe ECM illuminates the red STOP ENGINE light immediately when the diagnostic runs and fails.The torque output of the engine will be reduced.Maximum engine operating speed will be decreased.The engine will be shut OFF if the Engine Protection Shutdown feature is enabled.Conditions for Clearing the Fault CodeTo validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop-and-go city driving and steady state highwaye driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.To validate the repair using a Chassis Dynamometer Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the red STOP ENGINE lamp after the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults.
Shop TalkThe intake manifold air temperature sensor measures the temperature of the charge-air as it passes through the intake manifold.
Possible causes of this fault code include:
Restricted air flow through the charge-air coolerUndersized charge-air coolerHigh turbocharger compressor outlet temperature
Possible Cause:1) Intake manifold air temperature sensor failure2) ECM calibration