GUIDE-VALVE 3766566 - Caterpillar

Engine Cooling Fan Speed Sensor - Erratic, Intermittent, or IncorrectNote: CID 544 is no longer used in current software for this machine. Two event codes, E662, "High Engine Cooling Fan Speed" and E1363, "Low Engine Cooling Fan Speed" have replaced CID 544.
Illustration 1 g02256713
Schematic of the "Engine Cooling Fan" Speed Sensor
Diagnostic code CID 544 FMI 2 is recorded when the Brake ECM compares certain conditions of the machine to the data received from the sensor. The Brake ECM will issue this diagnostic code if the sensor data is not within expected parameters.Possible conditions of the sensor that can cause this diagnostic code are listed below:
The speed sensor is not installed correctly or has failed.
The signal circuit is shorted to ground.
The hydraulic fan system is out of adjustment or has failed.
The Brake ECM may have failed. (A failure of the ECM is unlikely.)System Response:When the CID 544 FMI 2 diagnostic code is active, the Brake ECM will not control the "engine cooling fan".Note: Before performing the following Test Steps, check to see that the speed sensor is securely mounted and adjusted correctly. Refer to Testing and Adjusting, KENR8395, "Speed Sensor - Adjust" If the speed sensor mount is secure and the 544-2 code is active, proceed to Test Step 1.Test Step 1. CHECK THE RESISTANCE OF THE CASE OF THE SENSOR
Turn the key start switch and the disconnect switch (if equipped) to the OFF position.
Disconnect the sensor from the machine harness.
At the sensor connector, measure the resistance between contact 1 and the case of the sensor. Measure also the resistance between contact 2 and the case of the sensor.Expected Result:The resistance for each measurement is greater than 10,000 ohms.Results:
OK - The resistance is greater than 10,000 ohms. Proceed to Test Step 2.
NOT OK - The resistance is NOT greater than 10,000 ohms. The fan speed sensor has failed.Repair: Replace the sensor.STOPTest Step 2. CHECK FOR AN OPEN WIRE IN THE HARNESS
The key start switch and the disconnect switch (if equipped) remain in the OFF position.
Disconnect the J2 harness connector from the Brake ECM.
At the disconnected machine wiring harness connector for the sensor, connect a jumper between contact A and contact B.
At the harness connector of the Brake ECM, measure the resistance from contact J1-6 (wire J803-BR(Brown)) to J1-7 (wire J804-WH(White)).Expected Result:The resistance is less than 5 ohms.Results:
OK - The resistance measurement is less than 5 ohms. The circuit is correct. Proceed to Test Step 3.
NOT OK - The resistance measurement is more than 5 ohms. The circuit is open in the machine harness or there is a faulty connection in the machine harness.Repair: Consult the complete electrical system schematic for this machine. Check all harness connectors that are in the speed sensor circuit. Ensure that the contacts of the connectors are clean, connected, and secure. Refer to Testing and Adjusting, KENR8395, "Electrical Connector - Inspect". After checking the connectors, repeat this Test Step. If the problem remains, check the wiring of the circuit for a broken wire. Repair the machine