88107A 5 Mariner KEY SWITCH

Illustration 1 g01194084
Illustration 2 g00725481
Throttle Position Versus PWM Input
Test Step 1. Check for Connector Damage.
Turn the Engine Control Switch (ECS) to the OFF/RESET position.
Disconnect the main power.
Thoroughly inspect the ECM connectors J1/P1 and 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 allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All 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 connectors and wiring are OK. 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.STOPTest Step 2. Check the Throttle Position on the Caterpillar Electronic Technician (ET).
Turn the ECS to the STOP position. The engine should be off.
Observe the position of the throttle on Cat ET.
Adjust the customer's speed control to the lowest setting.
Start at the lowest position. Slowly adjust the customer's speed control to the highest setting. Monitor the position of the throttle on Cat ET. Expected Result:The throttle position on Cat ET is 0 percent at the lowest setting and 0 to 100 percent as the speed control is adjusted to the highest setting.Results:
OK - The speed control is operating correctly.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 throttle position on Cat ET does not change correctly. Proceed to Test Step 3.Test Step 3. Check the Duty Cycle at the Customer Connector.
Turn the ECS to the OFF/RESET position.
Remove wire F702-BK(Black) for the throttle signal from the customer's connector on terminal BN.
Set the multimeter to "VDC". Press the "Hz" button twice so that the % symbol is displayed.
Place the red probe of the digital multimeter on terminal BN of the customer connector. Place the black probe of the multimeter on the −Battery terminal.
Turn the ECS to the STOP position. The engine should be off.
Measure the percent duty cycle of the throttle signal. Adjust the speed control from the lowest position to the highest position.
Turn the ECS to the OFF/RESET position.
Replace all connectors and wires. Expected Result:The duty cycle is 5 to 10 percent at the lowest setting. The duty cycle is 90 to 95 percent at the highest setting.Results:
OK - The duty cycle and throttle position readings are correct. Proceed to Test Step 3.
Not OK - The duty cycle reading is not correct. The throttle position signal is not reaching the ECM.Repair: Check the signal from the customer's connector to the speed control.STOPTest Step 4. Check the Duty Cycle at the ECM Connector.
Turn the ECS to the OFF/RESET position.
Remove the ECM connector P1 from the ECM. Remove the throttle signal wire F702-BK(Black) from the ECM connector P1-10.
Reconnect the ECM connector J1/P1.
Set the multimeter to "VDC". Press the "Hz" button twice so that the % symbol is displayed.
Place the red probe of the multimeter on wire F702-BK(Black) that was removed from P1-10 of the ECM connector P1. Place the black probe of the multimeter on the −Battery terminal.
Turn the ECS to the STOP position. The engine should be off.
Measure the percent duty cycle of the throttle signal. Move the speed control from the lowest setting to the highest setting.
Turn the ECS to the OFF/RESET position.
Replace all connectors and wires. Expected Result:The duty cycle is 5 to 10 percent at the lowest setting. The duty cycle is 90 to 95 percent at the highest setting.Results:
OK - The duty cycle and the throttle signal are correct.Repair: Temporarily replace the ECM and perform the test again. If the problem is resolved, the ECM is faulty. Permanently replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".STOP
Not OK - The duty cycle reading is not correct. The throttle signal is not reaching the ECM.Repair: Repair the wire F702-BK(Black) between ECM connector P1-10 and the customer connector BN.STOP