| Function of Self-diagnosis |
| The control of the automatic gearbox is electronic/hydraulic. |
| The term “self-diagnosis” is related to this electric/electronic control. |
| Control unit -J217- with driving situation circuits (Fuzzy Logic) |
| The gear-change point is determined automatically, according to driving conditions and road resistance. |
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| The maximum engine power is always available. |
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| Gear-change points are adapted to suit particular road conditions. |
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| Gear-change points changed as required. |
| Gear-change points change on upward and downward gradients |
| On upward or downward gradients, gear-changes are selected automatically by additional gear-change mapping, according to accelerator position and driving speed. |
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| On steep gradients, gear-change mapping is adapted to engine power output. |
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| On steep gradients, gear-change mapping is adapted to the braking effect of the engine. |
| Functions of gearbox control unit |
| The automatic gearbox control unit -J217- receives information from components that influence the shift controls and sends this information to the solenoid valves with which the piston slide valves are controlled in the slide valve body. |
| The control unit for the automatic gearbox -J217- is equipped with a fault memory to be able to rapidly determine the origin of the damage if an electric/electronic component fails or in the event of a line interruption. Faults are detected by eletric signals and are stored in the fault memory. |
| Electrical faults that influence the driveability can be determined with the vehicle system tester -V.A.G 1552-, -V.A.G 1551 - or -VAS 5051-. |
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| The description which follows relates to the vehicle system tester -V.A.G 1552- using program card 5.0 or higher version. |
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| The use of vehicle diagnosis, measurement and information system -VAS 5051- and the fault read-out scan tool -V.A.G 1551 - with integrated printer is similar. A minor deviation on the display read-out is possible. |
| Safety functions of the gearbox control unit |
| If there are critical faults when driving the gearbox must be operated in emergency running mode and you can drive on. If the malfunction occurs in “D”, “3”, or “2”, the 3rd gear emergency running mode is activated. |
| If the malfunction occurs in “1”,“P”, “N” or “R” the emergency running mode for the respective gear is activated. |
| After restarting in the emergency running mode and when the malfunction occurs (if the selector lever is in the selector lever position “D”, “3” or “2”) the 3rd gear is activated hydraulically until the fault has been rectified. |
| Faults that may result in emergency running mode: The gearbox will be activated in emergency running mode until the fault is no longer detected by the control unit over a given period of time. |
| Faults that may result in emergency running mode: |
| Line interruption, short-circuit, defective electric or hydraulic components. |
| Fault recognition of the gearbox control unit |
| If there is a fault, it is stored as a static (present) fault. If the fault is not indicated for a given time or over a certain driving distance it becomes a sporadic fault. |
| Faults, which are stored in the fault memory as sporadically existing faults, can be displayed as “sporadically occurring faults” during fault interrogation. “SP” appears on the right of the display. |
| Faults, which are stored as sporadically existing faults in the fault memory, are automatically erased after a driving distance of 1000 km or 20 hours driving time. |
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