78249 Mercury MOUNT, LOWER

Illustration 1 g01272251
Schematic
Illustration 2 g01154323
P1 ECM connector (P1-5) Digital return (P1-23) Engine shutdown switch (NO) (P1-40) Engine shutdown switch (NC)Test Step 1. Inspect Electrical Connectors and Wiring
Remove the electrical power from the ECM.
Thoroughly inspect the J1/P1 ECM connector. Thoroughly inspect the J700/P700 engine shutdown switch connector. 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 of the connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The harness and connectors are OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not OK.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 the Switch Status on Cat ET
Connect Cat ET to the service tool connector.
Restore the electrical power to the ECM.
Observe the status for "Shutdown Switch" on Cat ET while you operate the engine shutdown switch.
Remove the electrical power from the ECM.Expected Result:The status is "On" with the switch in the STOP position. The status is "Off" with the switch in the RUN position.Results:
OK - The switch is operating normally.Repair: Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - The status of the switch is incorrect. Proceed to Test Step 3.Test Step 3. Short the Wires at the Switch
Disconnect the connector for the shutdown switch.
Install a jumper wire between A (Engine shutdown switch (NC) and C (Digital sensor return) on the connector for the shutdown switch.
Restore the electrical power to the ECM and observe the status for "Shutdown Switch" on Cat ET.Note: Wait at least 30 seconds for the status of the switch to change.The status should be "Off".
Remove the electrical power from the ECM.
Remove the jumper wire.
Install the jumper wire between B (Engine shutdown switch (NO) and C (Digital sensor return) on the connector for the shutdown switch.
Restore the electrical power to the ECM and observe the status for "Shutdown Switch" on Cat ET.Note: Wait at least 30 seconds for the status of the switch to change.The status should be "On".
Remove the electrical power from the ECM.
Remove the jumper wire.Expected Result:The status is "Off" with the jumper wire between A (Engine shutdown switch (NC) and C (Digital sensor return) on the connector for the shutdown switch. The status changes to "On" when you move the jumper wire to B (Engine shutdown switch (NO) and C (Digital sensor return) on the connector for the shutdown switch.Results:
OK - The wiring from the connector for the shutdown switch to the ECM is OK. There is a problem with the switch.Repair: Temporarily connect a new switch. Verify that the new switch solves the problem before you permanently install the new switch.STOP
Not OK - The ECM did not detect the shorts. There is a problem in the harness and/or the ECM. Proceed to Test Step 4.Test Step 4. Short the Switch at the ECM
Remove the electrical power from the ECM.
Disconnect the J1/P1 ECM connector.
Fabricate three jumper wires that are long enough to short circuit terminals at the P1 ECM connector. Crimp connector sockets to one end of each of the jumper wires.
Remove the wires from terminal locations P1-5, P1-23, and P1-40 at the ECM connector. Install a jumper wire into each of these terminal locations.
Short circuit the ends of the jumper wires that are in terminal locations P1-5 (digital return) and P1-40 (engine shutdown switch (N/C)) at the ECM connector.
Restore the electrical power to the ECM and observe the status for "Shutdown Switch" on Cat ET.Note: Wait at least 30 seconds for the status of the switch to change.The status should be "Off".
Remove the electrical power from the ECM.
Short circuit the ends of the jumper wires that are in terminal locations P1-5 (digital return) and P1-23 (engine shutdown switch (N/O)) at the ECM connector.
Restore the electrical power to the ECM and observe the status for "Shutdown Switch" on Cat ET.The status should be "On".Note: Wait at least 30 seconds for the status of the switch to change.
Remove the electrical power from the ECM.
Restore the wiring to the original configuration.Expected Result:The switch status on Cat ET agrees with the test results.Results:
OK - The switch status on Cat ET agrees with the test results.Repair: There is a problem in the harness between the ECM and the harness connector for the shutdown switch. There may be a problem with a connector. Repair the harness and/or the connector. Replace parts, if necessary. Verify that the repair resolves the original problem.STOP
Not OK - The switch status on Cat ET does not agree with the test results that are stated above.Repair: There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM".STOP