Cummins ISX15 CM2250 (2010-12) Fault Code: 154 PID: 105 SPN: 105 FMI: 4 Intake Manifold 1 Temperature Sensor Circuit- Voltage Below Normal or Shorted to Low Source

Circuit Description
The 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 ECM for the engine protection system and engine emission control.

The electronic control module (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 Location
The intake manifold air temperature sensor is located in the air intake manifold.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes
The ECM detects that the intake manifold temperature signal voltage is less than 0.41 VDC for more than 10 seconds.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE light and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
A default value is used for the intake manifold temperature reading.
Diesel exhaust fluid injection into the aftertreatment system is disabled.
Active and stationary regeneration of the diesel particulate filter will be disabled.
The EGR valve will be closed.
Conditions for Clearing the Fault Code
To validate the repair, start the engine and let it idle for 1 minute.
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 amber CHECK ENGINE lamp after the diagnostic runs and passes.
For OBD engines, the ECM will turn off the MIL after 3 consecutive trips where the diagnostic runs and passes.
The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive faults, as well as extinguishthe MIL for OBD engines.

Shop Talk
The intake manifold temperature sensor shares return wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active. Check fault codes with multiple counts first.

Possible causes of this fault code include:

Signal circuit shorted to ground in the harness
Signal circuit shorted to return or ground in the sensor.

Possible Cause:
1) ECM failure
2) Engine Harness