Circuit DescriptionNormally, switches, accelerators, and other components are connected to the engine control module (ECM) directly through individual wires. Multiplexing allows those same components to be hard wired to an original equipment manufacturer (OEM) vehicle electronic control unit or transmission electronic control unit in the cab. Then component values and states from components such as sensors, accelerators, and switches can be transmitted from the OEM vehicle engine control unit to the Cummins® ECM over the SAE J1939 data link. Component LocationThe SAE J1939 data link wiring and SAE J1939 devices vary by OEM options. Conditions for Running the DiagnosticsThis diagnostic...

Circuit DescriptionThe aftertreatment diesel exhaust fluid controller is the central control for the selective catalytic reduction (SCR) diesel exhaust fluid dosing system, and handles the dosing activity, tank level sensing, tank temperature sensing, line heating, and tank heating. The diesel exhaust fluid controller communicates to the electronic control module (ECM) via the J1939 data link connection. Component LocationThe location of the aftertreatment diesel exhaust fluid controller varies by application and original equipment manufacturer (OEM). The controller will typically be mounted to the vehicle frame or suitable rigid bracket using 3 or 4 capscrews. Refer to the OEM service manual for...

Circuit DescriptionThe diesel exhaust fluid dosing unit performs many functions, one of which is to generate adequate diesel exhaust fluid pressure in the lines using a pump to allow for dosing. The diesel exhaust fluid controller provides a battery voltage supply and a ground to the diesel exhaust fluid dosing unit. The controller also supplies a signal to the dosing unit to control the diesel exhaust fluid output. This signal changes based on the diesel exhaust fluid pressure being commanded.. Component LocationThe aftertreatment diesel exhaust fluid dosing unit location is original equipment manufacturer (OEM) dependent. Refer to the OEM service...

Circuit DescriptionThe diesel exhaust fluid dosing unit performs many functions, one of which is to generate adequate diesel exhaust fluid pressure in the lines using a pump to allow for dosing. The diesel exhaust fluid controller provides a battery voltage supply and a ground to the diesel exhaust fluid dosing unit. The controller also supplies a signal to the dosing unit to control the diesel exhaust fluid output. This signal changes based on the diesel exhaust fluid pressure being commanded. Component LocationThe aftertreatment diesel exhaust fluid dosing unit location is original equipment manufacturer (OEM) dependent. Refer to the OEM service...

Circuit DescriptionThe mass air flow sensor is a frequency based device. A constant voltage is applied to a heated wire. This wire is positioned in the air stream and is heated by the electrical current that the voltage produces. As air flows across it, it cools down. The heated wire or film is a positive temperature coefficient (ptc) resistor. This means that the resistance drops when the temperature drops. The drop in resistance allows more current to flow through the wire in order to maintain the programmed temperature. This current is changed to a frequency which is sent to the...