CONTROL GP-TRANSMISSION HYD 4264366 - Caterpillar

The engine cooling fan speed sensor receives a supply voltage of 8.0 0.5 VDC from the ECM. The sensor outputs a frequency that is directly proportional to fan speed. There is a connector for a 4,700 Ohm pull-up resistor spliced into the harness near the sensor. The resistor is mounted near the cooling fan toward the front of the engine.The sensor generates a signal pulse for each revolution of the fan. The output frequency varies between 0.83 Hz to 30 Hz over the speed range between 50 rpm and 1800 rpm.
Illustration 2 g03612318
Schematic for the cooling fan speed sensorTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
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Location of the ECM connectors (3) J1/P1 ECM connectors
Thoroughly inspect the connectors for sensor (1) and resistor (2) . Also, thoroughly inspect ECM connector (3) . Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 4 g02154896
P1 ECM connector (P1-4) 8 V supply (P1-5) Return (P1-32) Cooling fan speed
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the allen head screw for each ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and the wiring for abrasion and for pinch points.Expected Result:All connectors, pins, and sockets are coupled and inserted and the harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are coupled. Verify that the repair eliminates the problem.STOPTest Step 2. Check the Status of the Engine Fan Speed with Caterpillar Electronic Technician (ET)
Remove the electrical power from the ECM.
Connect Cat ET to the service tool connector. Start Cat ET.
Restore the electrical power to the ECM.
Access the "Engine Fan Bypass" under the "Diagnostics" menu.
Start the "Engine Fan Bypass" on Cat ET. Set the fan speed to 800 rpm.
Use a 1U-6602 Photo-Tachometer to determine the actual speed of the fan.
Compare the engine fan speed that is reported by Cat ET to the actual engine fan speed that is reported by the photo-tachometer.
Deactivate the "Engine Fan Bypass".Expected Result:The actual fan speed is within 50 rpm of the engine fan speed that is reported by Cat ET.Results:
OK - The engine fan speed is within the desired rpm range.Repair: The sensor is operating correctly. There may be an intermittent electrical problem in a connector or in the harness. If an intermittent problem is suspected, refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - The engine fan speed is not within the desired rpm range. Proceed to Test Step 3.Test Step 3. Check the Supply Voltage at the Connector for the Speed Sensor
Remove the electrical power from