SHAFT 7T5653 - Caterpillar

System Operation Description:Use this procedure in order to troubleshoot the electrical system if a problem is suspected with the throttle signal. Use this procedure if the diagnostic code in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
Description Conditions which Generate this Code System Response
91-8 Throttle Position Sensor abnormal frequency, pulse width, or period The Electronic Control Module (ECM) detects an abnormal throttle signal for five seconds. The code is logged. Terminal BN on the customer connector provides the throttle signal to the engine's 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.Note: The ECM will not respond to the throttle signal if there is an active 253-02 Personality Module erratic, intermittent, or incorrect.
Illustration 1 g01194084
Illustration 2 g00725481
Throttle Position Versus PWM Input
Illustration 3 g01242355
P1 ECM connector
(P1-10) Throttle signal
Illustration 4 g01242356
Customer connector
(Terminal BN) Throttle signal
Illustration 5 g01234146
Location of ECM connectors
Test Step 1. Inspect Electrical Connectors and Wiring
Turn the ECS to the OFF position.
Thoroughly inspect the ECM connectors. Inspect all of the other connectors for the circuit. Refer to 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. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
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. 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 - There is a problem in the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Throttle Position on 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 speed control to the lowest setting.
Start at the lowest position. Slowly adjust the 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