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 it, in order to maintain the programmed temperature. This current is changed to a frequency which is sent to the engine...

Circuit DescriptionThe diesel exhaust fluid controller provides a 5 volt supply and a ground to the diesel exhaust fluid pressure sensor. The pressure sensor provides a signal to the diesel exhaust fluid controller on the sensor signal circuit. This sensor signal voltage changes based on the diesel exhaust fluid pressure supplied by the dosing unit. The diesel exhaust fluid controller will detect a low signal voltage at low diesel exhaust fluid pressures, and a high signal voltage at high diesel exhaust fluid pressures. The aftertreatment diesel exhaust fluid pressure sensor reading is communicated to the ECM via the engine data...

Circuit DescriptionThe aftertreatment diesel exhaust fluid controller communicates to the primary engine Electronic Control Module (ECM) through the J1939 public data link network. The aftertreatment diesel exhaust fluid controller also receives battery supply, keyswitch input, and ground from the OEM vehicle. Component LocationThe aftertreatment diesel exhaust fluid controller location is OEM dependent. Refer to the OEM service manual for more information. Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position. Conditions for Setting the Fault CodesData link communications between the ECM and the aftertreatment diesel exhaust fluid controller have been lost. Action Taken...

Circuit DescriptionThe aftertreatment diesel exhaust fluid controller is the central control for the aftertreatment diesel exhaust fluid dosing system, and handles the dosing activity, tank level sensing, tank temperature sensing, line heating, and tank heating. It communicates to the engine ECM via a J1939 data link connection. Component LocationThe location of the aftertreatment diesel exhaust fluid controller varies by application and 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 a more detailed component location description. Conditions for Running the DiagnosticsThis diagnostic...

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 OEM dependent. Refer to the OEM service manual for more...