SEAL 8P9142 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the throttle position sensor or the decelerator position sensor 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 Electronic Control Module (ECM) detects an incorrect frequency on the throttle signal or an incorrect duty cycle on the throttle signal. The frequency is below 150 Hz or the frequency in above 1000 Hz. The duty cycle is less than 7 percent or the duty cycle is greater than 95 percent.     The code is logged. The ECM flags the throttle position as invalid data and a default value of zero percent is used. The engine speed is limited to low idle.    
264-8 Deceleration Throttle abnormal frequency, pulse width, or period     The ECM detects an incorrect frequency on the signal for the decelerator position sensor or an incorrect duty cycle on the signal for the decelerator position sensor. The frequency is below 150 Hz or the frequency in above 1000 Hz. The duty cycle is less than 7 percent or the duty cycle is greater than 95 percent.     The code is logged. The ECM flags the signal for the decelerator position sensor as invalid data and the feature is disabled. The ECM will use the throttle position sensor for the desired throttle position.    Throttle Position SensorThe throttle position sensor provides the throttle signal to the ECM. The throttle position sensor is mounted to a throttle lever that allows the operator to control the speed of the engine. The geometry of the throttle lever arm controls both the travel of the sensor and the range of the output signal. The throttle position sensor cannot be adjusted.The output from the throttle position sensor is a PWM signal that varies with the position of the throttle lever. The throttle position sensor produces a minimum duty cycle in the released position and a maximum duty cycle in the full throttle position. When the lever is in the low idle position, the ECM translates the sensor's output signal to a throttle position of 0 percent. When the throttle lever is fully actuated, the ECM translates the output signal to a throttle position of 100 percent.Decelerator Position SensorThe deceleration pedal is used by the operator in order to decrease desired engine speed during operating conditions. The desired engine speed can be controlled by the operator from high idle, down to the "Deceleration Speed Set Point".The scaling factor for the deceleration pedal is calculated by the ECM upon powerup. The scaling factor is also calculated when the "Deceleration Speed Set Point" is changed. If the throttle lever is set below high idle, the deceleration pedal will not have an effect until the pedal has reached the proportional value that is equal to