GEAR-PUMP DRIVE 7N5250 - Caterpillar

The following background information is related to this procedure:Viscous Clutch Cooling Fan SolenoidThe viscous clutch cooling fan solenoid controls the engagement of the clutch that drives the engine cooling fan. The ECM determines the desired fan speed based on the ATAAC temperature and the coolant temperature. The viscous clutch cooling fan solenoid is controlled by a PWM signal from the ECM.
Illustration 1 g02484302
View of the connector for the cooling fan solenoid
(3) Cooling fan solenoid return
(4) Cooling fan solenoid control
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the P1/J1 ECM connectors and thoroughly inspect the connector for the fan drive assembly. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
B. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the fan drive assembly.
C. Check the screw for the ECM connector for the correct torque of 6 N m (53 lb in).
I. Disable the fan override.
Electrical connectors
Result: All connectors, pins, and sockets are correctly connected and the harness is free of corrosion, abrasion, and pinch points.
Proceed to Test Step 2.
Result: There is a fault in the connectors and/or the harness.
Repair: Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected.
Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
2. Check for Active Diagnostic Codes
A. Remove the electrical power from the ECM.
B. Verify that the solenoid connectors are free of debris and connected securely.
C. Connect the electronic service tool to the diagnostic connector.
D. Restore the electrical power to the ECM.
E. Select diagnostic tests on the electronic service tool.
F. Select the "Override Parameters" screen.
G. Activate the fan override.
H. Monitor the active diagnostic code screen on the electronic service tool. Check and record any active diagnostic codes. Wait at least 30 seconds in order for the diagnostic code to become active.
I. Disable the fan override.
Active Diagnostic Codes
Result: No diagnostic codes are active.
The problem may have been related to a faulty connection in the harness. Carefully inspect the connectors and wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Result: A 4212-5 or 291-5 code is active at this time.
Proceed to Test Step 2.
Result: A 4212-6 or 291-6 code is active at this time.
Proceed to Test Step 3.
3. Create a Short Circuit in the Harness at the Solenoid
A. Turn the keyswitch to the OFF position.
B. Disconnect the connector for the fan drive assembly.
C. Fabricate a jumper wire that is long enough to create a short between the terminals of the connector for the fan drive assembly. Crimp connector pins to each end of the jumper wire.
D. Install the wire between pin 3 and pin 4 on the harness connector for the fan drive assembly in order to create a short circuit.
E. Turn the keyswitch to the ON position. Wait for 10 seconds. Check for active diagnostic codes on the electronic service