8M0007781 Mercury CABLE ASSEMBLY, Ground

Illustration 1 g00934772
SchematicTest Step 1. Inspect Electrical Connectors and Wiring
Turn the keyswitch to the OFF/RESET position.
Thoroughly inspect the throttle lock switch, the J1/P1 ECM connector, the J3/P3 machine connector, and the associated wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.Expected Result:All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are free of corrosion, of abrasion, 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
Connect the Caterpillar Electronic Technician (Cat ET) to the service tool connector.
Turn the keyswitch to the ON position.
Observe the status for "Throttle Lock Switch" on Cat ET while you operate the throttle lock switch.Expected Result:The status for "Throttle Lock Switch" reads "ON" when the throttle lock switch is pressed once. The status for "Throttle Lock Switch" reads "OFF" when the throttle lock switch is pressed again.Results:
OK - The throttle lock switch is operating properly at this time.Repair: Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent. Stop.
Not OK - The throttle lock switch is not operating correctly. Proceed to Test Step 3.Test Step 3. Short the Wires at the Throttle Lock Switch
Turn the keyswitch to the OFF position.
Disconnect J87/P87 connector at the throttle lock switch.
Make a short jumper wire with male spade terminals on each end.
Connect the jumper wire across terminals 2 and 3 on the J87/P87 connector.
Turn the keyswitch to the ON position, and observe the status for "Throttle Lock Switch" on Cat ET.
Momentarily connect the jumper wire to terminals 2 and 1. Return the jumper wire to terminals 2 and 3.
Observe the status for "Throttle Lock Switch" on Cat ET.
Momentarily connect the jumper wire to terminals 2 and 1. Return the jumper wire to terminals 2 and 3.
Observe the status for "Throttle Lock Switch" on Cat ET.
Leave the connector disconnected from the switch. Remove the jumper wire.Expected Result:The status changed from "OFF" to "ON" when the jumper wire is placed on terminal 1 and terminal 2. The status returns to "OFF" when the jumper wire is placed on terminal 1 and terminal 2 again.Results:
OK - The ECM and the wiring harness are functioning properly. Replace the throttle lock switch. Verify that the repair eliminates the problem. Stop.
Not OK - Proceed to Test Step 3.Test Step 4. Check for a Short Circuit in the Wiring Harness
Illustration 2 g00938550
ECM connector P1
Disconnect the J1/P1 ECM connector, and ensure that the wires at the throttle lock switch are disconnected.
Measure the following resistances:
P1:14 (Throttle Lock Switch (NC)) to P1:29 (Digital Return)
P1:20 (Throttle Lock Switch (NO)) to P1:29 (Digital Return)
P1:14 (Throttle Lock Switch (NC)) to P1:20 (Throttle Lock Switch (NO))
P1:20 (Throttle Lock Switch (NO)) and the engine ground
P1:14 (Throttle Lock Switch (NC)) and the engine groundExpected Result:The resistance is greater than 20,000 Ohms for each measurement.Results:
OK - There are no shorts in the harness. Proceed to Test Step 5.
Not OK - There is a short circuit in the harness or connectors.Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.Test Step 5. Check the Resistance through the Harness
Ensure that the J1/P1 ECM connector and the wires at the throttle lock switch are disconnected.
Connect the jumper wire across terminals 2 and 3 at connector P87.
Measure the resistance between P1:14 (Throttle Lock Switch (NC)) and P1:29 (Digital Return).
Move the jumper wire to terminals 1 and 2 at connector P87.
Measure the resistance between P1:20 (Throttle Lock Switch (NO)) and P1:29 (Digital Return).
Disconnect the shorted wires.Expected Result:The resistance is less than 10 Ohms for each measurement.Results:
OK - The harness is good. Proceed to Test Step 6.
Not OK - There is an open circuit or excessive resistance in the harness or the connectors.Repair: Repair the circuit.Verify that the repair eliminates the problem. Stop.Test Step 6. Short the Switch Inputs at the ECM
Illustration 3 g00934801
P1 ECM connector (wire side)
Turn the keyswitch to the OFF position.
Remove the following wires from the P1 ECM connector:
P1:14 (Throttle Lock Switch (NC))
P1:20 (Throttle Lock Switch (NO))
P1:29 (Digital Return)
Fabricate three jumper wires out of 18 AWG insulated wire with Deutsch socket terminals on one end of each jumper wire.
Insert the end of the jumper wires with the socket into P1:14 (Throttle Lock Switch (NC)), P1:20 (Throttle Lock Switch (NO)), and P1:29 (Digital Return) on the P1 ECM connector.
Reconnect the J1/P1 ECM connector.
Turn the keyswitch to the ON position.Note: Additional diagnostic codes will be generated because P1:29 (Digital Return) will no longer be connected to other sensors and switches. Clear the additional diagnostic codes upon completing this test.
Connect the jumper wires from P1:14 (Throttle Lock Switch (NC)) and P1:29 (Digital Return). Observe the status for "Throttle Lock Switch" on Cat ET.
Momentarily connect the jumper wires from P1:29 (Digital Return) and P1:20 (Throttle Lock Switch (NO)). Reconnect the jumper wires from P1:14 (Throttle Lock Switch (NC)) and P1:29 (Digital Return). Observe the status for "Throttle Lock Switch" on Cat ET.
Momentarily connect the jumper wires from P1:29 (Digital Return) and P1:20 (Throttle Lock Switch (NO)). Reconnect the jumper wires from P1:14 (Throttle Lock Switch (NC)) and P1:29 (Digital Return). Observe the status for "Throttle Lock Switch" on Cat ET.
Turn the keyswitch to the OFF position, and remove the jumper wire from the ECM connector P1. Reconnect the following wires to the ECM connector P1:
P1:14 (Throttle Lock Switch (NC))
P1:20 (Throttle Lock Switch (NO))
P1:29 (Digital Return)Expected Result:The status reads "Off" when the jumper wire is connected to P1:14 and P1:29. The status reads "On" when the jumper wire is momentarily connected to P1:14 and P1:29. The status reads "Off" when the jumper wire is momentarily connected to P1:14 and P1:29 again.Results:
OK - The ECM properly reads the switch inputs at the ECM connector P1 but not at the switch.Repair: The wiring harness is faulty. Repair the wiring harness. Verify that the repair eliminates the problem. Stop.
Not OK - Correct switch inputs appear at the ECM connector P1 but the ECM is not reading the inputs properly.