SEAL-O-RING 0328970 - Caterpillar

System Operation Description:Terminal BN on the customer connector provides the throttle signal to the engine's Electronic Control Module (ECM). The throttle signal should be a 500 Hz constant frequency signal with a pulse width that varies with the throttle signal. This output signal is referred to as a Pulse Width Modulated signal (PWM). This signal is expressed as a percentage between 0 percent and 100 percent.The throttle signal's duty cycle should be between 5 percent to 10 percent at low idle and 90 percent to 95 percent at high idle. The percent duty cycle is translated in the ECM into the throttle position of 0 percent to 100 percent. Use this procedure to troubleshoot an active diagnostic code of 91-08 Throttle Position signal abnormal. The ECM will not respond to the throttle signal if there is an active 253-02 Personality Module mismatch.
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.