RING 6H5474 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the cooling fan speed sensor. Also use this procedure if the diagnostic code in Table 1 is active or easily repeated.
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