42623 3 Mercury CHECK VALVE

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Schematic
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P1 ECM connector (P1-43) Engine fan control solenoid (P1-51) Solenoid returnTest Step 1. Inspect Electrical Connectors and Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the ECM connector J1/P1. Inspect all of the other connectors for the circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
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 ECM connector (allen head screw) for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
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 are 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 Caterpillar Electronic Technician (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.
Determine if the problem is related to an open circuit diagnostic code (05) or a short circuit diagnostic code (06).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 reinspect the connectors and wiring. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - A short circuit diagnostic code (06) is active at this time. Proceed to Test Step 3.
Not OK - An open circuit diagnostic code (05) is active at this time. Proceed to Test Step 4.Test Step 3. Disconnect the Connector for the Fan Control Solenoid in Order to Create an Open Circuit
Remove the electrical power from the ECM.
Disconnect the connector for the fan control solenoid.
Restore the electrical power to the ECM. Wait at least 30 seconds for activation of the diagnostic codes.
Access the "Active Diagnostic Code" screen on Cat ET. Check for an active open circuit diagnostic code (05) for the fan control solenoid.
Remove the electrical power from the ECM.Expected Result:An open circuit diagnostic code (05) is now active for the fan control solenoid.Results:
OK - A short circuit diagnostic code (06) was active before disconnecting the connector. An open circuit diagnostic code (05) became active after disconnecting the connector.Repair: Temporarily connect a new fan control solenoid to the harness, but do not install the new fan control solenoid. Verify that there are no active diagnostic codes for the solenoid. If there are no active diagnostic codes for the solenoid, permanently install the new solenoid. Clear any logged diagnostic codes.STOP
Not OK - There is a short circuit between the solenoid harness connector and the ECM. Leave the solenoid connector disconnected. Proceed to Test Step 5.Test Step 4. Create a Short at the Connector for the Fan Control Solenoid
Remove the electrical power from the ECM.
Install a jumper wire with Deutsch sockets on each end between terminal 1 (fan control solenoid) and terminal 2 (solenoid return) on the solenoid connector. Connect the jumper on the harness side of the connector.
Restore the electrical power to the ECM.
Wait at least 30 seconds for activation of the short circuit diagnostic code (06).Note: Monitor the "Active Diagnostic Codes" screen on Cat ET before installing the jumper wire and after installing the jumper wire.
Remove the jumper wire.
Remove the electrical power from the ECM.Expected Result:A short circuit diagnostic code (06) is active when the jumper wire is installed. An open circuit diagnostic code (05) is active when the jumper wire is removed.Results:
OK - The engine harness and the ECM are OK.Repair: Temporarily connect a new fan control solenoid to the harness, but do not install the new fan control solenoid. Verify that there are no active diagnostic codes for the solenoid. If there are no active diagnostic codes for the solenoid, permanently install the new solenoid. Clear any logged diagnostic codes.STOP
Not OK - The open circuit diagnostic code (05) remains active with the jumper in place. The open circuit is between the ECM and the connector for the fan control solenoid. Proceed to Test Step 5.Test Step 5. Check the Operation of the ECM
Disconnect the J1/P1 ECM connector.
Remove the wire for the fan control solenoid from P1-43. Install a jumper wire with Deutsch sockets on each end into P1-43.
Remove the wire for the fan control solenoid from P1-51. Install a jumper wire with Deutsch sockets on each end into P1-51.
Reconnect the ECM connector.
Restore the electrical power to the ECM. Monitor the "Active Diagnostic Code" screen on Cat ET. Wait at least 30 seconds for activation of the code.An open circuit diagnostic code (05) should be active for the fan control solenoid.
Check the operation of the ECM by creating a short at the ECM.
Install a wire jumper between the jumper wire for the fan control solenoid and the jumper wire for the solenoid return.
Monitor the "Active Diagnostic Code" screen on Cat ET. Wait at least 30 seconds for activation of the code.A short circuit diagnostic code (06) should be active when the wire jumper is installed.
Remove the wire jumpers. Reconnect all wires and connectors.Expected Result:An open circuit diagnostic code (05) is active when the wire from the fan control solenoid is removed f