ROD ASSEM. 3G8761 - Caterpillar

Table 1
Diagnostic Codes Table for Cooling Fan Speed    
J1939 Code     CDL Code     Code Description     Comments    
1639-17     E1363 (1)     Low Engine Cooling Fan Speed     The code is logged.    The engine cooling fan speed sensor provides a signal to the Electronic Control Module (ECM). The ECM controls fan speed by varying the current to the fan control solenoid.The engine cooling fan speed sensor receives a supply voltage from the ECM. The sensor outputs a frequency that is directly proportional to fan speed. The sensor generates a signal pulse for each revolution of the fan. The output frequency varies between 5 Hz to 180 Hz over the speed range between 50 rpm and 1800 rpm.During the following procedure, refer to the electrical schematic for the application.
Table 2
Required Tools    
Tool     Part Number     Part Description     Qty    
A     351-8635     Tachometer Kit     1    Complete the procedure in the order in which the steps are listed.
Table 3
Troubleshooting Test Steps     Values     Results    
1. Check the Status of the Engine Fan Speed
A. Turn the keyswitch to the OFF position.
B. Connect the electronic service tool to the diagnostic connector.
C. Turn the keyswitch to the ON position.
D. Access the "Fan Override Test" under the "Diagnostics" menu.
E. Start the "Fan Override Test" on Cat ET. Set the fan speed to 500 rpm.
F. Use Tooling (A) to determine the actual speed of the fan.
G. Compare the engine fan speed that is reported by the electronic service tool to the actual engine fan speed that is reported by Tooling (A) .
H. Deactivate the "Fan Override Test".
I. Turn the keyswitch to the OFF position.
   
Fan Speed    
Result: The engine fan speed is within 50 rpm.
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 Troubleshooting, "Electrical Connectors - Inspect".
Result: The engine fan speed is not within 50 rpm.
Proceed to Test Step 2.    
2. Check the Sensor Supply Voltage at the Sensor Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the sensor connector from the wiring harness.
C. Turn the keyswitch to the ON position.
D. Measure the sensor supply voltage between terminal 2 and terminal 3.
   
Supply Voltage    
Result: The supply voltage is not reaching the sensor.
Repair: Refer to Troubleshooting, "Sensor Supply - Test".
Result: The supply voltage is reaching the sensor.
Proceed to Test Step 3.
   
3. Check the Signal Frequency at the Sensor Connector
A. Turn the keyswitch to the OFF position.
B. Remove the wire from terminal 1 on the sensor side of the connector. Connect the sensor connector.
C. Turn the keyswitch to the ON position.
D. Access the "Fan Override Test" under the "Diagnostics" menu on the electronic service tool.
E. Start the "Fan Override Test" on the electronic service tool. Set the fan speed to 800 rpm.
F. Use a multimeter to measure the frequency