SPACER 3J4278 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the fuel metering valve. Also use this procedure if one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table    
Description    Conditions which Generate this Code    System Response    
1446-8 Fuel Metering Module : Abnormal Frequency, Pulse Width, or Period     The fuel metering valve has detected an error in the PWM signal that is from the Electronic Control Module (ECM).     The code is logged.
The alarm output is activated.    
1446-9 Fuel Metering Module : Abnormal Update Rate     The ECM has not received the last ten messages that were expected from the fuel metering valve over the CAN data link.    
1446-12 Fuel Metering Module : Failure     After the ECM has been powered for 5 seconds, the fuel metering valve has reported that an internal fault has occurred.     The code is logged.
The alarm output is activated.
The shutdown output is activated.
The engine is shut down.    
1446-13 Fuel Metering Module : Calibration Required     After the ECM has been powered for 5 seconds, the fuel metering valve has reported that a calibration is necessary for the valve.     The code is logged.
The alarm output is activated.    
1447-12 Fuel Metering Sensor Module : Failure     The fuel metering valve has detected an internal failure of the sensor module. The problem was reported to the ECM over the CAN data link.     The code is logged.
The alarm output is activated.
The shutdown output is activated.
The engine is shut down.    The fuel metering valve is an electronic gas valve that controls the flow of fuel to the engine. The valve works with the engine ECM in order to ensure the correct flow of gas in all conditions of engine operation. The valve converts the command signal and the information into a valve position that directly corresponds to the desired gas flow. The position of the valve is compensated by these additional factors that are internal to the valve:
A signal for absolute fuel pressure
Differential pressure across the valve
Fuel temperature sensorsCommunicationsThe ECM sends the following information to the fuel metering valve via the CAN data link:
Specific gravity of the fuel
Specific Heat Ratio of the fuel
Desired fuel flow rateThe fuel metering valve sends the following information to the ECM via the CAN data link:
Position of the fuel valve
Absolute fuel pressure
Differential pressure across the valve
Fuel temperatureIf the ECM and the fuel metering valve cannot communicate via the CAN data link, a 1446-9 diagnostic code is activated. If the engine is running, the fuel metering valve will use the command signal from the PWM signal. The engine will continue to run. However, if the engine is not running and a 1446-9 diagnostic code becomes active, the ECM will not allow the engine to start.PWM SignalThe ECM sends a command signal for the fuel flow via a PWM signal. If the PWM signal for the flow of fuel