0310135 JOHNSON BUSHING, Pilot

Table 1
Diagnostic Code Table for Cooling Fan Speed
J1939 Code Code Description Comments
1639-17 Fan Speed : Low - least severe (1) 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.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 the electronic service tool. 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 between the signal wire from the sensor and engine ground.
G. Deactivate the "Fan Override Test".
H. Turn the keyswitch to the OFF position.
I. Restore all connectors and wiring to the original configuration.
Sensor Frequency
Result: The frequency is approximately 80 Hz.
The engine cooling fan speed sensor is generating the correct signal.
Repair: Repair the harness or replace the harness.
Verify that the fault is resolved.
Result: The frequency is not approximately 80 Hz.
Repair: Replace the fan speed sensor.
Verify that the fault is resolved.
If the fault is still present, contact the Dealer Solutions Network (DSN).