STEP AS 4547803 - Caterpillar

Illustration 1 g01527008
Schematic of the position sensor for the retarder
This diagnostic trouble code is associated with the position sensor for the retarder. The FMI 8 means that the ECU has determined that the signal frequency or the signal pulse width is not within the expected range.The position sensor is a PWM sensor that has a frequency of 500 Hz. The duty cycle operates from a range of 10% to 90%. As the lever is moved downward the duty cycle increases. The possible causes of this diagnostic code are listed below:
The sensor has failed.
Intermittent connections or poor connections
Mechanical devices are loose.
The ECU has failed. This is unlikely.Note: The following test procedure may create other diagnostic trouble codes. Ignore these created diagnostic trouble codes and clear the diagnostic trouble codes when the original diagnostic trouble code has been corrected. Ensure that the diagnostic trouble code of SPN 1716 FMI 8 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure. Test Step 1. CHECK FOR POWER AT THE SENSOR.
Do not disconnect the harness connector from the sensor.
At the back of the harness connector for the sensor, use