26802 Mercury O-RING

Illustration 1 g00676748
SchematicTest Step 1. Inspect Electrical Connectors and Wiring.
Turn the keyswitch to the OFF/RESET position.
Thoroughly inspect ECM connector J1/P1, machine connector J3/P3, and any other connectors in the engine shutdown circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and wiring for abrasion and for pinch points from the engine shutdown switches to the ECM.Expected Result:All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are free of corrosion, of abrasions, and of pinch points.Results:
OK - Proceed to Test Step 2.
Not OK - Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.Test Step 2. Check the Status of the Shutdown Switch on the Cat ET
Connect Cat ET to the data link connector.
Turn the keyswitch to the ON position. The engine is OFF.
Observe the status for "Shutdown Switch" on Cat ET while you toggle the engine shutdown switches.Expected Result:The status reads "ON" when either switch is in the SHUTDOWN (up) position. The status reads "OFF" when both switches are in the RUN (down) position.Results:
OK - Both shutdown switches are operating normally.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent. Stop.
Not OK - Proceed to Test Step 3.Test Step 3. Check the Switches.
Disconnect both engine shutdown switches.
Set each switch to the RUN (down) position and check for continuity between Terminals A and B at the connector for each switch.
Set each switch to the SHUTDOWN (up) position and check for continuity between Terminals B and C at the connector for each switch.Expected Result:The resistance is less than 10 Ohms for both switches.Results:
OK - Both switches are functioning properly. Proceed to Test Step 4.
Not OK - There is a problem with at least one of the switches.Repair: Replace the suspect engine shutdown switch.Verify that the repair eliminates the problem. Stop.Test Step 4. Check the Resistance through the Harness.
Illustration 2 g00677003
ECM connector P1 (ECM side)
Turn the keyswitch to the OFF/RESET position.
Set both engine shutdown switches to the RUN (down) position.
Disconnect ECM connector J1/P1.
Measure the resistance between P1-27 (Engine Shutdown NC) and P1-23 (Crank/Key).
Set the ground level engine shutdown switch to the SHUTDOWN (up) position. Leave the engine compartment engine shutdown switch in the RUN (down) position.
Measure the resistance between P1-22 (Engine Shutdown NO) and P1-23 (Crank/Key).
Set the ground level engine shutdown switch to the RUN (down) position and the engine compartment engine shutdown switch to the SHUTDOWN (up) position.
Measure the resistance between P1-22 (Engine Shutdown NO) and P1-23 (Crank/Key).Expected Result:The resistance is less than 10 Ohms for each measurement.Results:
OK - The harness resistance is within acceptable limits. Proceed to Test Step 5.
Not OK - There is an open circuit or excessive resistance in the harness.Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.Test Step 5. Check for Shorts in the Harness
Illustration 3 g00677003
ECM connector P1 (ECM side)
Turn the keyswitch to the OFF/RESET position.
Set the engine compartment engine shutdown switch to the RUN (down) position.
Disconnect ECM connector J1/P1.
Disconnect the ground level engine shutdown switch.
Measure the resistance between P1-22 (Engine Shutdown NO) and chassis ground. Also, measure the resistance between P1:22 and all the other pins.
Measure the resistance between P1-23 (Crank/Key) and chassis ground. Also, measure the resistance between P1:23 and all the other pins.
Measure the resistance between P1-27 (Engine Shutdown NC) and chassis ground. Also, measure the resistance between P1:27 and all the other pins.Expected Result:The resistance is greater than 20,000 Ohms for each measurement.Results:
OK - Proceed to Test Step 6.
Not OK - There is a short in the harness between the switch and the ECM.Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.Test Step 6. Short the Input at the ECM.
Illustration 4 g00677003
J1/P1 breakout
Turn the keyswitch to the OFF/RESET position.
Disconnect both engine shutdown switches.
Install a 7X-1715 Adapter Cable (40-PIN BREAKOUT) at ECM connector J1/P1.
Turn the keyswitch to the ON position. The engine is OFF.
Use a suitable piece of wire to short P1-27 (Engine Shutdown NC) and P1-23 (Crank/Key) at the breakout.
Observe the status for "Shutdown Switch" on Cat ET.
Remove the wire short.
Use a suitable piece of wire to short P1-22 (Engine Shutdown NO) and P1-23 (Crank/Key) at the breakout.
Observe the status for "Shutdown Switch" on Cat ET.Expected Result:The status reads "OFF" when the wire short is inserted between P1-27 (Engine Shutdown NC) and P1-23 (Crank/Key). The status reads "ON" when the wire short is inserted between P1-22 (Engine Shutdown NO) and P1-23 (Crank/Key).Results:
OK - There is a problem in the harness between the ECM and the engine shutdown switches.Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.
Not OK - The correct switch inputs appear at the ECM, but the ECM is not reading the switch inputs properly.Repair: Verify your results. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" before replacing the ECM. Stop.