879345T88 Mercury MANUAL TRIM ASSEMBLY

Illustration 1 g00934701
Test Step 1. Check for Connector Damage.
Turn the keyswitch to the OFF position.
Thoroughly inspect the ECM connector J1/P1 and the machine connector J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test 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 2.25 0.25 N m (20 2 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 the wiring are okay. Proceed to Test Step 2.
Not OK - The connectors and/or wiring need repair.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 2. Check the Status of the Throttle Backup Switch on Cat ET.
Connect Cat ET to the cab service tool connector J31. Start Cat ET.
Turn the keyswitch to the ON position. The engine should be off.
Operate the throttle backup switch. Observe the status for the throttle backup switch on Cat ET.Expected Result:The status of the throttle backup switch reads "ON" when the throttle backup switch is in the ON position. The status of the throttle backup switch reads "OFF" when the throttle backup switch is in the OFF position.Results:
OK - The status of the throttle backup switch reads "ON" with the throttle backup switch in the ON position. The status of the throttle backup switch reads "OFF" when the throttle backup switch is in the OFF position. The throttle backup switch is operating normally.Repair: There may be an intermittent problem. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors". Stop.
Not OK - The status of the throttle backup switch does not read "ON" with the throttle backup switch in the ON position. The status of the throttle backup switch does not read "OFF" when the throttle backup switch is in the OFF position. The throttle backup switch is not operating normally. Proceed to Test Step 3.Test Step 3. Short the Wires together at the Throttle Backup Switch.
Turn the keyswitch to the OFF position.
Record the position of the wiring on the throttle backup switch before removing the wires.
Disconnect the wires from the throttle backup switch.
Create a short circuit at the throttle backup switch between the wire C940-GN and the digital return wire 998-BR.
Turn the keyswitch to the ON position. The engine should be off.
Observe the status of the throttle backup switch on the Cat ET.
Turn the keyswitch to the OFF position.
Remove the short between the wire C940-GN and the digital return wire 998-BR.
Turn the keyswitch to the ON position. The engine should be off.
Observe the status of the throttle backup switch on Cat ET.
Turn the keyswitch to the OFF position.
Remove the wire short.Expected Result:The status of the throttle backup switch reads "ON" when the wire C940-GN and the digital return wire 998-BR are shorted together. The status for the throttle backup switch reads "OFF" when the wire C940-GN and the digital return wire 998-BR are not shorted together.Results:
OK - The status of the throttle backup switch reads "ON" when the wire C940-GN and the digital return wire 998-BR are shorted together. The status of the throttle backup switch reads "OFF" when the wire C940-GN and the digital return wire 998-BR are not shorted together. The problem is not with the harness and/or the ECM.Repair: Temporarily connect a new throttle backup switch. Verify that the new throttle backup switch solves the problem before you permanently install the new throttle backup switch. Stop.
Not OK - The status of the throttle backup switch does not read "OFF" when the wire C940-GN and the wire 998-BR are shorted together. The status of the throttle backup switch does not read "ON" when the wire C940-GN and the wire 998-BR are shorted together. There is a problem in the harness and/or in the ECM. Proceed to Test Step 4.Test Step 4. Check for a Short Circuit in the Wiring Harness.
Turn the keyswitch to the OFF position.
Disconnect the ECM connector J1/P1 and disconnect the wires at the throttle backup switch.
Measure the resistance between the wire C940-GN at ECM connector P1-25 and the digital return wire 998-BR at ECM connector P1-9.
Measure the resistance between the wire C940-GN at the ECM connector P1-25 and the engine ground.
Measure the resistance between the wire 998-BR at the ECM connector P1-9 and the engine ground.Expected Result:The resistance is greater than 20,000 Ohms for each measurement.Results:
OK - The resistance is greater than 20,000 Ohms for each measurement. Proceed to Test Step 5.
Not OK - The resistance is less than 20,000 Ohms for one or more of the measurements. There is a short circuit in the harness between the throttle backup switch and the ECM.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 5. Check for an Open Circuit in the Harness.
Create a short circuit at the throttle backup switch between the wire C940-GN and the digital return wire 998-BR.
Measure the resistance between the wire C940-GN at the ECM connector P1-25 and the digital return wire 998-BR at the ECM connector P1-9.
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. The resistance is not within acceptable limits. There is an open or excessive resistance in the harness.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 6. Check the Input to the ECM from the Throttle Backup Switch.
Disconnect the ECM connector J1/P1.
Remove the wire C940-GN at the ECM connector P1-25. Remove the digital return wire 998-BR from ECM connector P1-9. Use a 151-6320