SHAFT 2160036 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the speed control or if the diagnostic code in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table    
Code and Description    Conditions which Generate this Code    System Response    
91-8 Throttle Position Sensor abnormal frequency, pulse width, or period     The Engine's Electronic Control Module (ECM) detects a sensor frequency that is less than 150 Hz or a sensor frequency that is greater than 1000 Hz for two seconds.
or
The ECM detects a duty cycle that is less than 5 percent or a duty cycle that is greater than 95 percent for one second.     The code is logged.
The throttle signal defaults to a zero percent duty cycle (low idle).    The speed control is used to provide a throttle signal to the engine control. The output from the speed control for rated speed is a pulse width modulated signal. The signal varies with the position of the speed adjust potentiometer. The ECM calculates the desired engine speed from the signal from the speed control. The rated speed signal is valid when the duty cycle is in the range of 5 to 95 percent. If the ECM detects a rated speed signal that is invalid, the engine will be set to low idle.Some applications may choose not to use the speed control. Some applications may use a load sharing unit. The unit is configured to provide the engine control with a rated speed signal. Some of these units cannot provide a signal until the engine is running. In these cases, perform troubleshooting while the engine is running.
Illustration 1 g01268064
Typical schematic
Illustration 2 g01268069
P1 ECM connector (P1-05) Digital return (P1-10) Primary throttle
Illustration 3 g01212010
Machine interface connector (Terminal 09) Digital return (Terminal 10) Primary throttle
Illustration 4 g01234146
Location of ECM connectorsTest Step 1. Inspect Electrical Connectors and Wiring
Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.
Turn the breaker for the ECM to the OFF position.
Thoroughly inspect the ECM connector J1/P1. Inspect all of the Connectors in the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
Check the ECM connector (allen head screw) for the proper torque. 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 harness and the wiring for abrasion and pinch points.Expected Result:The components and wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - The wiring and connectors are OK. Proceed to Test Step 2.
Not OK - The wiring and/or connectors need repair.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 2. Check the Voltage at the Speed Control
Connect the red probe of the digital multimeter to the +Battery terminal of the speed control. Connect the black probe of the digital multimeter to the −Battery terminal of the speed control.Expected Result:The digital multimeter reads 24