PUMP AS-FUEL INJECTION 6N7527 - Caterpillar

System Operation Description:Use this procedure to troubleshoot suspect problems with the circuit for the fuel metering valve.This procedure covers the following diagnostic codes:
1446-5 Fuel Metering Module : Current Below Normal
1446-9 Fuel Metering Module : Abnormal Update Rate
1446-12 Fuel Metering Module : Failure
1446-13 Fuel Metering Module : Calibration Required
1447-12 Fuel Metering Sensor Module : FailureThe fuel metering valve is an electronic gas valve that controls the flow of fuel to the engine. The valve works with the Electronic Control Module (ECM) in order to ensure the correct flow of fuel in all conditions of engine operation.The ECM sends a command signal for the flow of fuel and information about the specific gravity of the gas to the fuel metering valve. 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: absolute fuel pressure, differential pressure of the valve and fuel temperature.The following procedure tests whether the command signal for the flow of fuel and the information about the specific gravity of the gas is properly sent to the fuel metering valve by the ECM. The command signal is a 180 hertz pulse width modulated signal (PWM). Information about the specific gravity of the gas is sent to the fuel metering valve via the CAN data link.The fuel metering valve sends information to the ECM via the CAN data link. This procedure also tests whether the following information is properly sent to the ECM by the fuel metering valve: position of the fuel valve, absolute fuel pressure, differential pressure of the valve and fuel temperature.During normal operation, the valve receives two command signals from the ECM. One of the signals is a digital signal that is received via the CAN data link. The other signal is a PWM signal that is received via a pair of wires. The valve will use the digital signal when both signals are available.If the PWM signal is not available, the valve will continue to use the digital signal. The ECM will activate a 1446-5 diagnostic code. Engine performance will be affected.If the digital signal is not available, the valve will use the PWM signal. The ECM will activate a 1446-9 diagnostic code. Engine performance will be affected.Status Indicator for the Fuel Metering Valve
Illustration 1 g00996218
Status indicator for the fuel metering valve
The fuel metering valve contains a status indicator. The indicator flashes in different colors during operation in order to indicate the status of the valve:Green - Normal operationOrange - The valve has detected a problem and the valve continues to operate.Red - The valve has detected a serious problem. The valve has shut down.The flash code indicates the particular error that has been detected by the valve. Before performing maintenance on the valve, observe the status indicator. Refer to Installation and Operation Manual, SEBU7630, "Woodward Raptor Gas Regulation and Metering Valve/Actuator System" for additional information.Note: If an