ELECTRONICS GP 1451710 - Caterpillar

Table 1
Diagnostic Codes for Cooling Fan Control
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
- 485-5 Engine Fan Reversing Solenoid : Current Below Normal The current for the fan reversing solenoid control signal is below an acceptable value.
The code is logged.
A warning will appear on the display on the control panel.
The Electronic Control Module (ECM) loses the ability to reverse the engine cooling fan.
- 485-6 Engine Fan Reversing Solenoid : Current Above Normal The current for the fan reversing solenoid control signal is below an acceptable value.
The code is logged.
A warning will appear on the display on the control panel.
The ECM loses the ability to reverse the engine cooling fan.
- 486-3 Engine Fan Reverse Switch voltage above normal The voltage for the fan reversing switch is above an acceptable value.
The code is logged.
A warning will appear on the display on the control panel.
- 486-4 Engine Fan Reverse Switch voltage below normal The voltage for the fan reversing switch is below an acceptable value.
The code is logged.
A warning will appear on the display on the control panel. The purpose of a reversing fan is to clean debris from the radiator. This is done by temporarily reversing the direction of the air flow through the radiator fins in order to purge the radiator fins. For some applications, the reversing fan is used to heat the engine compartment during cold-weather operation.In the automatic mode, the fan reversing solenoid is controlled by the engine Electronic Control Module (ECM). The ECM will automatically reverse the direction of the fan rotation. The ECM will use a preset time interval to cycle the fan reversing solenoid.Note: On some applications the fan reversing solenoid may be controlled by a relay. Refer to the appropriate Electrical Schematic.The operator can manually reverse the fan rotation by pressing the engine fan reverse switch. While the momentary switch is depressed, the direction of the fan rotation will reverse. Once the switch is allowed to reset, the fan returns to normal operation and control of the fan will return to the automatic operation.Use this procedure to troubleshoot any suspect problems with the engine fan reverse switch or the fan reversing solenoid.Refer to the Electrical Schematic for the application while performing the following procedure.
Table 2
Troubleshooting Test Steps Values Results
1. Determine the Diagnostic Code
A. Establish communication between the electronic service tool and the engine Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Download the "Warranty Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.
C. Look for one of the diagnostic codes listed in Table 1.
Active Codes
Result: An active or logged 485-5 code is present.
Proceed to Test Step 2.
Result: An active or logged 485-6 code is present.
Proceed to Test Step 3.
Result: An active or logged 486 code is present.
Proceed to Test Step 5.
2. Check for an Open Circuit
A. Turn the keyswitch to the OFF position.
B. Disconnect the engine reversing fan solenoid connector from the wiring harness.
If the solenoid is controlled by a relay, disconnect