Cumminz

Circuit DescriptionThe sensor supply 3 circuit provides a 5 volt supply to the primary engine speed/position sensor. Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running. Conditions for Setting the Fault CodesThe electronic control module (ECM) detects the sensor supply 3 signal voltage is more than a calibratible value for more than 1 second. 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.-The backup engine speed sensor will...

Circuit DescriptionThe ambient air temperature sensor is a variable resistor sensor and is used to measure the temperature of the ambient air. The engine control module (ECM) uses this temperature reading to optimize engine performance, and determine if heating of the SCR system is required. The electronic control module (ECM) supplies 5 volts to the ambient air temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the ambient air temperature. Component LocationThe mounting location for the ambient air temperature sensor is OEM dependent. Refer to the appropriate OEM...

Circuit DescriptionThe vehicle speed sensor senses the speed of the tailshaft gear on the vehicle’s transmission. This speed signal is then transmitted to the engine electronic control module (ECM) and converted into a vehicle speed. Component LocationThe vehicle speed sensor is located in the rear of the vehicle transmission. Refer to the OEM service manual for location. Conditions for Running the DiagnosticsThis diagnostic runs continuously when the vehicle is in motion. Conditions for Setting the Fault CodesThe ECM detects a loss of vehicle speed when other engine operating conditions indicate that the vehicle could possibly be in motion. Action Taken...

Circuit DescriptionThe fan speed sensor is a variable resistance speed sensor. It consists of a coil of wire and an iron core. The target on the fan hub shaft is a ground flat in the center of the shaft. The engine control module (ECM) interprets this signal and converts it to a fan speed reading. Component LocationThe fan speed sensor is located in the fan hub assembly. Refer to the original equipment manufacturer (OEM) troubleshooting and repair manual. Conditions for Running the DiagnosticsThis diagnostic runs continuously when the engine is running. Conditions for Setting the Fault CodesThe ECM detects that...

Circuit DescriptionThe vehicle speed sensor senses the speed of the tailshaft gear on the vehicle transmission. This speed signal is then transmitted to the engine electronic control module (ECM) and converted into a vehicle speed. Component LocationThe vehicle speed sensor is located in the rear of the vehicle transmission. Conditions for Running the Diagnostics-The adjustable parameter “VSS Anti-Tampering” must be enabled.-This diagnostic runs continuously when the vehicle is in motion, if the feature is enabled. Conditions for Setting the Fault CodesThe ECM detects a tampering event of the vehicle speed signal. Action Taken When the Fault Code is Active-The ECM...