COUPLING AS 2500873 - Caterpillar

Detailed FMI Explanation
FMI 00 - "Data Valid But Above Normal Operating Range." Every electronic control system sets a high limit for the "expected" operating range of the signal. The limit includes "over range" signals such as high converter temperatures. A sensor that is still working but sending a signal above the expected limit will cause an FMI 00 to be stored. Some possible causes of FMI 00 are listed here:
Signal above normal (High "pressure/temperature")
Calibration is needed. "FMI 13 is the preferred code."For example, a certain PWM sensor is expected to generate a valid signal over 80 percent duty cycle. If the sensor generates a signal of 81 percent duty cycle, the sensor is still working but the signal is above the expected signal limits. FMI 01 - "Data Valid But Below Normal Operating Range." Every electronic control system sets a low limit for the "expected" operating range of the signal. The limit includes "under range" signals such as a low "engine oil pressure signal" from a working sensor. A sensor that is still working but sending a signal below the expected limit will cause an FMI 01 to be stored. Some possible causes of FMI 01 are listed here:
The signal is below normal. (The "voltage", "pressure", or "temperature" is low.)
Timing is retarded. For example, a certain PWM sensor is not expected to generate a PWM signal below 5 percent duty cycle even with zero air pressure. If the sensor generates a signal of 4 percent duty cycle with the engine shutdown, the sensor is still working but the signal is below the expected signal limits. FMI 02 - "Data Erratic, Intermittent Or Incorrect." Signal data that is received from a component is valid. The data that is received from the component has become intermittent or erratic. Data can be correct sometimes and the data may be incorrect at other times. The communication that occurs between electronic controls also relates to this condition. For example, when VIDS is looking for the engine speed from the electronic engine control over the Cat data link. The data has been intermittent 10 times in a 10 minute period.Some possible causes of FMI 02 are listed here:
Loose connections in switches, harness, etc.
Intermittent/erratic signal
Programmed data has changed.
Noisy signal
The signal is out of range. "FMI 00 or FMI 01 is the preferred code."
A failed power or ground connection to the ECM
Failed ECMFMI 03 - "Voltage Above Normal Or Shorted High." The voltage that is received from a component is higher than the expected value that is identified by the "CID". FMI 03 most often relates to a signal circuit. Some possible components that can cause an FMI 03 are listed here:
The sensor (switch)
The harness
The related electronic control Some possible causes of an FMI 03 are listed here:
A "non-duty cycle related sensor output" is stuck at the maximum output of the sensor.
A harness that has the sensor signal wire shorted to any voltage that is greater than the voltage of the sensor power supply.
A sensor signal