FA618397 Force DECAL, ENGINE COVER PORT W/LITERATURE

Table 1
Diagnostic Codes Table
CDL Code Code Description Comments
291-5 Engine Cooling Fan Solenoid : Current Below Normal The Electronic Control Module (ECM) detects an open circuit and/or a short to the +Battery in the circuit for the engine fan control solenoid.
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.
Illustration 1 g02133274
Location of the solenoid for the cooling fan control
The ECM controls the rpm of the engine fan in order to provide the following benefits:
Increased productivity
Noise from the fan is reduced.
Improved fuel economy
Overcooling of the engine is reduced.The fan control solenoid controls the displacement of the hydraulic pump that supplies pressurized oil to the fan motor. The ECM controls the speed of the fan by controlling the current to the fan control solenoid. The current to the engine fan control solenoid varies between 0.0 (maximum fan rpm) to 1.4 amperes (minimum fan rpm). The ECM adjusts the current to the engine fan control solenoid in order to keep the fan rpm within 50 rpm of the desired rpm. The fan pump defaults to maximum pressure and a diagnostic code is generated if the ECM detects an open or a ground in the solenoid circuit.The engine cooling fan pump pressure sensor provides feedback to the ECM about the hydraulic oil pressure that is available at the fan pump. The ECM uses the feedback from the engine cooling fan pump pressure sensor in order to compare the pump pressure to a set of maps that are stored in the software of the ECM. The maps are used by the ECM to calculate the desired fan drive pump pressure. If the fan's actual pump pressure is different from the calculated pressure, the ECM will vary the current to the engine fan control solenoid in order to match the pump pressure to the calculated pressure.The ECM monitors engine coolant temperature and intake manifold air temperature in order to determine the correct fan rpm. The fan speed is increased as the coolant temperature and intake air temperature increase. When a system fault is detected, fan rpm is increased. When the engine is lugging, the fan rpm is reduced in order to reduce the load on the engine. The fan's rpm will also be restricted due to the altitude.An override is available with Caterpillar Electronic Technician (ET). This allows the fan to be manually changed from the minimum to the maximum possible rpm. If the ECM detects a problem with the solenoid circuit, a diagnostic code is generated. If the ECM detects a system fault, the ECM provides minimum current to the solenoid. This ensures a maximum fan speed while the fault condition exists.
Illustration 2 g02132713
Schematic for the engine fan control solenoid
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 3 g02133275
Location of J1/P1 ECM connectors
Thoroughly inspect the J1/P1 ECM connectors. Inspect all of the other connectors that are in the circuit for the engine fan control solenoid. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Illustration 4 g01415857
P1 ECM connector
(P1-43) Hydraulic Fan Solenoid (12V)
(P1-51) Hydraulic Fan Solenoid (−)
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the allen head screw on each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem in the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Cat ET to the service tool connector.
Turn the keyswitch to the ON position.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Select diagnostic tests from Cat ET.
Select the "Override Parameters" screen on Cat ET.
Activate the fan override.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active.
Disable the fan override.
Determine if the problem is related to an open circuit diagnostic code 291-5 or a short circuit diagnostic code 291-6. Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: 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".STOP
Not OK - A short circuit diagnostic code 291-6 is active at this time. Proceed to Test Step 3.
Not OK - An open circuit diagnostic code 291-5 is active at this time. Proceed to Test Step 4.Test Step 3. Disconnect the Connector for the Engine Fan Control Solenoid in Order to Create an Open Circuit
Turn the keyswitch to the OFF position.
Disconnect the connector for the engine fan control solenoid.
Turn the keyswitch to the ON position.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Select diagnostic tests from Cat ET.
Select the "Override Parameters" screen on Cat ET.
Activate the fan override.
Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic code to become active.
Disable the fan override. Expected Result:An open circuit diagnostic code 291-5 is now active for the engine fan control solenoid.Results:
OK - A short circuit diagnostic code 291-6 was active before disconnecting