2940 Mercruiser PLATE ASSEMBLY, COMMUTATOR END

Illustration 1 g00840212
Typical schematic
Illustration 2 g01075111
P1 ECM Connector (P1-19) User defined shutdownTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF position.
Thoroughly inspect the ECM connector J1/P1. Inspect all of the other connectors. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
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 of 6.0 N m (55 lb in).
Check the customer connector (allen head screw) for the proper torque of 2.25 0.25 N m (20 2 lb in).
Check the harness and the wiring for abrasion and for pinch points.Expected Result:The connectors and wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - The connectors and wiring are OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring need repair.Repair: Repair the connectors and/or wiring or replace the connectors or wiring.STOPTest Step 2. Check the Status of the User Defined Shutdown on Caterpillar Electronic Technician (ET)
Ensure that the user defined shutdown switch is in the OFF position.
Connect Cat ET to the cab service tool connector J42. Start Cat ET.
Engage the parking brake.
Turn the keyswitch to the ON position. The engine should be off.
Observe the status for the user defined shutdown on Cat ET.Expected Result:The status reads "OFF".Results:
OK - The status reads "OFF". The status is correct. Proceed to Test Step 3.
Not OK - The status does not read "OFF". The status is incorrect. Proceed to Test Step 4.Test Step 3. Create a Short at the Connector for the User Defined Shutdown
Use a jumper wire with a socket terminal at one end to short wire F721-GY to the chassis ground. Create the short at the connector for the user defined shutdown.Expected Result:Cat ET indicates "User Shutdown ON" when the wire F721-GY is shorted to chassis ground.Results:
OK - Cat ET indicates "User Shutdown ON" when the wire F721-GY is shorted to chassis ground. Cat ET indicates the correct status. The shutdown feature is working properly.Repair: There may be an intermittent problem. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - Cat ET does not indicate "User Shutdown ON" when the wire F721-GY is shorted to chassis ground. Cat ET does not show the correct status. Proceed to Test Step 5.Test Step 4. Check the Harness for a Short Circuit
Turn the keyswitch to the OFF position.
Disconnect ECM connector J1/P1.
Measure the resistance at the ECM connector between P1-19 and every pin in ECM connector P1.
Measure the resistance at the ECM connector between P1-19 and the engine ground.Expected Result:The resistance is greater than 20,000 Ohms.Results:
OK - The resistance is greater than 20,000 Ohms. Proceed to Test Step 6.
Not OK - The resistance is less than 20,000 Ohms. There is a short circuit in the harness or a user defined device is activating the shutdown feature.Repair: Repair the connectors and/or wiring or replace the connectors or wiring.STOPTest Step 5. Check the Harness for an Open Circuit
Turn the keyswitch to the OFF position.
Use a wire with a socket terminal at one end. Short wire F721-GY to the chassis ground at the connector for the user defined shutdown.
Disconnect the ECM connector J1/P1.
Measure the resistance at the ECM connector between P1-19 and engine ground.
Remove the wire short.Expected Result:The resistance is less than 5 Ohms.Results:
OK - The resistance is less than 5 Ohms. The resistance is within acceptable limits. Proceed to Test Step 6.
Not OK - The resistance is greater than 5 Ohms. There is an open circuit in the harness.Repair: Repair the connectors and/or wiring or replace the connectors or wiring.STOPTest Step 6. Short the Wire at the ECM
Remove the wire from the ECM connector at P1-19.
Insert a wire with a socket terminal at one end into the ECM connector at P1-19.
Reconnect ECM connector J1/P1.
Turn the keyswitch to the ON position. The engine should be off.
Momentarily short the jumper wire at P1-19 to the chassis ground.
Turn the keyswitch to the OFF position.
Remove the wire short. Reconnect ECM connector J1/P1.Expected Result:Cat ET indicates "User Shutdown ON" with the wire short in place. Cat ET indicates "User Shutdown OFF" when the wire short is removed.Results:
OK - Cat ET indicates "User Shutdown ON" with the wire short in place. Cat ET indicates "User Shutdown OFF" when the wire short is removed. Cat ET indicates the correct status. The feature is working properly.Repair: Repair the connectors and/or wiring or replace the connectors or wiring. There may be an intermittent problem. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - Cat ET does not indicate "User Shutdown ON" with the wire short in place. Cat ET does not indicate "User Shutdown OFF" when the wire short is removed. Cat ET does not indicate the correct status.Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM".STOP