LINES GP- 2391212 - Caterpillar

Illustration 1 g01208251
Engine cooling fan speed sensor connections
This diagnostic code is recorded when the ECM compares certain machine conditions and the data received from the sensor. The ECM will issue this diagnostic code if the sensor data is not within certain parameters. Possible sensor conditions that can cause this diagnostic code are listed:
The signal circuit is shorted to ground.
The speed sensor is not installed correctly.
The speed sensor has failed.
The ECM has failed. This is unlikely.System Response:When the CID 0544 FMI 02 diagnostic code is active. Machine response will be:
The ECM will not control the engine cooling fan correctly.Note: Before performing the following Test Steps, check to see that the speed sensor is mounted securely. If the speed sensor mount is secure and the CID 0544 FMI 02 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 A and the case of the sensor and between contactB 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 speed sensor has failed.Repair: Replace the sensor.STOPTest Step 2. CHECK FOR AN OPEN WIRE IN THE MACHINE HARNESS.
The key start switch and the disconnect switch (if equipped) remain in the OFF position.
Disconnect the machine harness ECM connector J2 from the ECM.
At the disconnected machine wiring harness connector for the sensor, connect a jumper between contact A and contact B.
At the machine harness ECM connector, measure the resistance from contact J2-14 (wire Y785-YL(Yellow)) to J2-20 (wire Y786-PU(Purple)). 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. After checking the connectors, repeat this Test Step. If the problem remains, check the circuit wiring for a broken wire. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK FOR A SHORT IN THE SIGNAL CIRCUIT OF THE MACHINE HARNESS.Note: The machine harness connectors remain disconnected from the sensor and the ECM. Remove the jumper that was installed in the last step.
The key start switch and the disconnect switch (if equipped) remain in the OFF position.
At the machine harness connector for the ECM, measure the resistance between contacts J2-14 to frame ground or to a ground contact on connectors J1 or J2. The ground contact on