Fault phenomenon:
   A 2000 Audi A6 2.8 car, with 100,000 KM of mileage, carrying ATX type engine and 01 v transmission. In the course of driving, the upshift of the car is normal when gently step on accelerator pedal, but when step on accelerator pedal urgently, the transmission won’t upshift after up to 3rd gear, neither can it be upshift nor downshift but just remained at 3rd gear position, and the transmission cannot be upshift when loosening accelerator pedal, the upshift of the transmission will not be normal until trampling on the accelerator pedal once again when the speed is down or transmission downshift to 1st or 2nd gear.
Inspection and analysis:
   After the trial test, we affirm that the fault phenomenon was the same as user mentioned, in the commissioning process, we have found another problem that if we change auto mode into manual mode when the fault occurred, the transmission upshift and downshift is normal which indicates that there is no problem in the mechanical aspect of gearbox. To connect Fcar auto diagnostic scanner so as to query the engine system and no fault code was found,  then to query the transmission system, also no fault code have been found.
   Transmission based primarily on throttle position signal, the speed signal and engine load signal and other main signals to carry out the operation of upshift and downshift, use car diagnostic scanner to read transmission data stream, and each data are in the normal range when checking the first area of 002 groups (throttle position signal), the third area of 003 groups of the (vehicle speed signal), and the first area of 004 group (ATF oil temperature).  Trample on the accelerator pedal slowly when the vehicle was in parking state, at last we found the throttle position sensor signal had an instantaneous change which indicates that the throttle position sensor has problems. After reference to the information about prompt of throttle valve potentiometer, we known that if 01 v transmission matching with vehicles equipped with electronic throttle , the former throttle position signal changed into upshift signal and was controlled by accelerator pedal position sensor G79 and G185 , the related data in data stream also shows the signal value of accelerator pedal. Dismount the accelerator pedal assembly, use a multimeter to measure the resistance of G79 and G85, throughout the process of the accelerator pedal movement, the accelerator pedal position sensor do have conditions that resistance can't change continuously, which show that the sensor open circuit.
   Troubleshooting: replace accelerator pedal assembly, then perform self-adaption of kickdown, test run and fault removed.
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