GUARD GP-WINDOW 2835425 - Caterpillar

Table 1
Diagnostic Codes Table    
Code and Code Description     Conditions which Generate this Code     System Response    
291-5
Engine Cooling Fan Solenoid : Current Below Normal     The Electronic Control Module (ECM) detects an open circuit in the circuit for the engine fan control solenoid.     The ECM sends minimum current to the fan control solenoid. The code is logged.    
291-6
Engine Cooling Fan Solenoid : Current Above Normal     The ECM detects a short circuit to ground in the circuit for the engine fan control solenoid.    
4212-5
Fan Drive Bypass Command Status : Current Below Normal     The Electronic Control Module (ECM) detects an open circuit in the circuit for the engine fan control solenoid.     The ECM sends minimum current to the fan control solenoid. The code is logged.    
4212-6
Fan Drive Bypass Command Status : Current Above Normal     The ECM detects a short circuit to ground in the circuit for the engine fan control solenoid.    The ECM monitors engine coolant temperature, intake manifold air temperature, and hydraulic oil temperature. The ECM monitors the sensors in order to determine the correct speed for the engine cooling fan.The ECM controls the speed of the fan by controlling the current to the engine fan control solenoid. The engine fan control solenoid controls the amount of oil pressure to the fan clutch by allowing oil to bypass the fan clutch. The fan clutch drives the fan. When the ECM outputs minimum current to the engine fan control solenoid, less oil is bypassed. The fan clutch will now drive the fan at a higher rpm. When the ECM outputs maximum current to the engine fan control solenoid, more oil is bypassed. The fan clutch will now drive the fan at a lower rpm.If the ECM detects a system fault, the ECM provides minimum current to the solenoid. Minimum current ensures a maximum fan speed while the fault condition exists.
An override is available with Cat® Electronic Technician (Cat® ET). An override allows the fan to be manually changed from the minimum to the maximum rpm.
Illustration 1 g03011017
Table 2
Troubleshooting Test Steps    Values    Results    
1. Check for Active Diagnostic Codes
A. Remove the electrical power from the ECM.
B. Verify that the solenoid connector is free of debris and connected securely.
C. Connect Cat ET to the service tool connector.
D. Restore the electrical power to the ECM.
E. Select diagnostic tests from Cat ET.
F.Select the "Override Parameters" screen on Cat ET.
G. Activate the fan override.
H. Monitor the active diagnostic code screen on Cat ET. 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 short