Golf Mk4
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Self-diagnosis function
Self-diagnosis function
The automatic gearbox is controlled electro-hydraulically. The term "self-diagnosis" is specifically for the electronic/electric control. Additional information
Control unit -J217- with driving situation gear changes (Fuzzy Logic) Determining the driving situation and driving resistance dependent gear change point happens automatically. Advantages:
Gear change point variations for gradients An additional gear change map automatically selects gear changes for gradients dependent upon accelerator pedal position and driving speed.
Vehicles with data BUS Comprehensive information on the "data bus" is given in self study programme No. 186. Advantages:
Safety functions of gearbox control unit The automatic control unit -J217- receives information from components that effect selection of gears and passes the information on to solenoid valves that control the valves in the valve body. The control unit is equipped with a fault memory so that in the event of an electronic/electrical component failure or on open circuit the fault can be determined quickly. Fault are recognized by electrical signals and stored in the fault memory. If faults occur in the monitored sensors or components, these are stored in the memory together with an indication of the type of fault. Faults which only occur once, are known as sporadic faults (temporary). Sporadic faults are additionally identified as such. After analysing the information the automatic gearbox control unit distinguishes between sporadic and static (permanent) faults => Fault table, from page 01-36 and stores these. If faults do not reoccur within Electrical faults that affect vehicle performance can be determined with the fault reader V.A.G 1551. The possibilities offered by self-diagnosis can only be fully exploited with operating mode 1 "Rapid data transfer" of fault reader V.A.G 1551. Functions which the fault reader V.A.G 1551 can register , List of selectable functions. Safety functions of gearbox control unit If critical faults occur when driving, the gearbox will continue to operate in an emergency running mode. If the fault occurs in "D", "3" or "2", then 3rd gear emergency mode is activated. If the fault occurs in "1","P", "N" or "R" then the emergency running mode for that stage is activated. If the engine is started again in the emergency running mode and the fault occurs when selector lever is in position "D", "3" or "2" then 3rd gear is activated hydraulically, until the fault is rectified. For faults which can lead to emergency running: Faults which may lead to emergency running: Open circuit in wiring, short-circuit, electrical or hydraulic components defective. Wiring open circuit and/or data Bus wiring short circuit. Gearbox control unit fault recognition If a fault exists it is stored as a static fault. If the fault no longer exists after a predetermined period or distance travelled, it is considered a sporadic fault. Faults which are stored in the memory as sporadically occurring faults, will be displayed as "sporadic faults" when retrieved by fault reader V.A.G 1551. "SP" appears on the right of the display in such cases. If the printer is switched on, "sporadic faults" are printed out after the fault is addressed. Faults which are stored in the memory as sporadically occurring faults are automatically erased after 1,000 km (625 miles) or 20 hours. Inoperative Data bus signals will be detected by the control unit on vehicles equipped with Data bus. Defective Data bus wiring e.g. open circuits can be directly detected. Conclusions cannot be drawn as to where the Data bus wiring is defective, until all control unit fault memories have been interrogated. Fault reader V.A.G 1551
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