GEAR-DISC 4826794 - Caterpillar

Illustration 1 g02709231
Schematic of the Engine Cooling Fan Pump Pressure Sensor
This diagnostic code is recorded when the ECM reads the input signal from the Engine Cooling Fan Pump Pressure Sensor and determines that the signal frequency or the signal pulse width is not within the expected range.The sensor is a PWM sensor that operates at a frequency of approximately 500Hz 100Hz. The sensor sends a PWM input signal to the ECM. The duty cycle of the signal will vary from 3% to 97%.If the PWM frequency is outside the 500Hz 100HZ operating range, an FMI 08 diagnostic code will be activated.The possible causes for this diagnostic code are listed:
Intermittent connections or poor connections in the wire harness.
The sensor has failed.
The ECM has failed. ECM failure is unlikely.System Response:
The events related to this sensor signal will not work properly.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected.Ensure that the diagnostic code of CID 0290 FMI 08 is active before performing this procedure.Note: Note: A digital multimeter is required for taking measurements in this procedure.Test Step 1. CHECK THE DUTY CYCLE AND THE SIGNAL FREQUENCY AT THE SENSOR
Turn the key start switch and the disconnect switch to the OFF position.
At the machine harness connector for the sensor, use a 151-6320 Removal Tool to remove the signal wire F725-WH(White)and the socket at contact 3 from the harness connector. The machine harness connector remains connected to the sensor.
At the back of the sensor connector, insert 7X-1710 Multimeter Probes along the ground contact 2 and the signal contact 3.
Turn the disconnect switch and the key start switch to the ON position.
Measure the frequency of the signal from the sensor.
Observe the measurement and wiggle the sensor connector. Gently pull on the wires and wiggle the wires.
Measure the duty cycle of the sensor at the connector pins between the contacts 2 and 3. Check that the sensor is within range according to the description at the beginning of this procedure.Expected Result:The frequency and duty cycle of the signal is correct according to the description at the beginning of this procedure. The frequency and the duty cycle are stable during the manipulation of the harness connector and the wiring.Results:
OK - The signal frequency and the duty cycle of the sensor is correct. The sensor is not the cause of the problem. Proceed to Test Step 2.
NOT OK - The signal frequency or the duty cycle of the sensor is not correct according to the description at the beginning of this procedure. The sensor has failed.Repair: Perform this test step again in order to verify that the sensor signal is not correct.The operation of the sensor is not correct. Replace the sensor. After replacement, verify that the operation is correct before operating the machine.STOPTest Step 2. CHECK FOR AN OPEN IN THE SENSOR CIRCUIT
Turn the key start switch and the disconnect switch to the OFF