46335 Mercruiser NUT, (.375-24)

Table 1
Diagnostic Codes Table
Code and 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 and/or a short to the +Battery 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. The ECM controls the speed of the engine cooling fan in order to provide the following benefits:
Increased productivity
Reduced noise
Improved fuel economy
Reduced overcooling of the engineThe ECM monitors engine coolant temperature, intake manifold air temperature, and hydraulic oil temperature 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 pressure to the fan pump by allowing oil to bypass the fan pump. The fan pump drives the fan. When the ECM outputs minimum current to the engine fan control solenoid less oil is bypassed and the fan pump will drive the fan at a higher rpm. When the ECM outputs maximum current to the engine fan control solenoid more oil is bypassed and the fan pump will drive the fan at a lower rpm.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.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.
Illustration 1 g01194820
Schematic for the engine fan control solenoid
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Illustration 2 g01141049
J1/P1 ECM connector (typical left side engine view)
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 3 g01113249
P1 ECM connector
(P1-43) Engine fan control solenoid
(P1-51) Solenoid return
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
Remove the electrical power from the ECM.
Connect Cat ET to the service tool connector.
Restore the electrical power to the ECM.
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 (5) or a short circuit diagnostic code (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 (6) is active at this time. Proceed to Test Step 3.
Not OK - An open circuit diagnostic code (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
Remove the electrical power from the ECM.
Disconnect the connector for the engine fan control solenoid.
Restore the electrical power to the ECM.
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 (5) is now active for the engine fan control solenoid.Results:
OK - A short circuit diagnostic code (6) was active before disconnecting the connector. An open circuit diagnostic code (5) became active after disconnecting the connector.Repair: Temporarily connect a new engine fan control solenoid to the harness, but do not install the new engine fan control solenoid. Verify that there are no active diagnostic codes for the engine fan control solenoid. If there are no active diagnostic codes for the engine fan control solenoid, permanently install the new engine fan control solenoid. Clear any logged diagnostic codes.STOP
Not OK - A short circuit diagnostic code (6) remains active when the connector for the engine fan control solenoid is disconnected. There is a short circuit between the harness connector for the engine fan control solenoid and the ECM. Proceed to Test Step 5.Test Step 4. Create a Short at the Connector for the Engine Fan Control Solenoid
Remove the electrical power from the ECM.
Fabricate a jumper wire that is long enough to create a short between the terminals of the connector for the engine fan control solenoid. Crimp connector