Description of On-Board Diagnostics - 4 Speed Automatic 01M

On Board Diagnostic (OBD), Function
The automatic transmission is controlled electrohydraulically. On Board Diagnostic (OBD) refers specifically to the electronic/electric controls of the automatic transmission

Transmission Control Module -J217- with driving adaptive gear shift points (fuzzy logic)
The transmission control module determines the driving dependent gear shift points automatically.
- Advantages:
- Gear shifts will be directed toward optimum fuel consumption
- Maximum engine output is always available
- Individual adaptation of shift points in all driving situations
- Gear shift points are infinitely variable

Shift point variations for hills
An additional gear shift map automatically selects shifts for hills dependent upon accelerator pedal position and driving speed.
- Gear shift map for extreme uphill stretches is matched to engine output
- Gear shift map for extreme downhill stretches is matched to the braking effect of the engine

Vehicles with CAN-Bus
Comprehensive information on the "CAN-Bus" can be found in self study program No. 186.

Advantages:
- Rapid data transfer between the control module
- Less wiring in vehicle

Safety functions of Transmission Control Module (TCM) -J217-
The TCM -J217- receives information from components that effect the selection of gears and passes the information on to solenoid valves in the valve body.

The control module is equipped with a Diagnostic Trouble Code (DTC) memory so that in the event of an electronic/electrical component malfunction or on open circuit the location can be determined quickly. Malfunctions are recognized by electrical signals and stored in the DTC memory.

If malfunctions occur in the monitored sensors or components, these are stored in the DTC memory together with an indication of the type of malfunction.

Malfunctions which only occur once are known as sporadic (temporary) malfunctions. Sporadic malfunctions are additionally identified as such.

After analyzing the information the TCM distinguishes between sporadic and static (permanent) malfunctions and stores these. 4 Speed Automatic 01M

If malfunctions do not reoccur within a minimum of 5 km (3 miles) or 6 minutes or a maximum of 20 km (12 miles) or 24 minutes, they are stored as sporadic malfunctions.

Electrical malfunctions that affect vehicle performance can be determined with the VAG 1551 Scan Tool.

The diagnostic possibilities can only be fully exploited with operating mode 1 "Rapid data transfer" of the VAG 1551 Scan Tool.

For a list of functions which the VAG 1551 Scan Tool can register Selectable Functions When Using VAG 1551/1552 or Vas 5051

Emergency running mode
If critical malfunctions occur when driving, the transmission will continue to operate in an emergency running mode. If the malfunction occurs in "D", "3" or "2", then 3rd gear emergency running mode is activated.

If the malfunction 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 malfunction occurs when the selector lever is in position "D", "3" or "2", then 3rd gear is activated hydraulically until the malfunction is corrected.

For all malfunctions which can lead to emergency running mode, the transmission will remain in this mode; until the malfunction is no longer recognized by the TCM over a predetermined period.

Malfunctions which may lead to emergency running:
- Open circuit in wiring
- short circuit in wiring
- electrical or hydraulic components faulty
- Wiring open circuit and/or CAN-Bus wiring short circuit.

TCM -J217- malfunction recognition
If a malfunction exists it is stored as a static malfunction. If the malfunction no longer exists after a predetermined period or distance traveled, it is considered a sporadic malfunction.

Sporadic malfunctions are stored in the memory and displayed as "sporadic malfunctions" when retrieved by the VAG 1551 Scan Tool. "SP" appears on the right of the display in such cases. If the printer is switched on, sporadic malfunctions are printed out after the malfunction is addressed.

Malfunctions which are stored in the memory as sporadically occurring malfunctions are automatically erased after 1,000 km (625 miles) or 20 hours.

Inoperative CAN-Bus signals will be detected by the control module on vehicles equipped with CAN-Bus. Faulty CAN-Bus wiring e.g. open circuits, can be directly detected. Conclusions cannot be drawn as to where the CAN-Bus wiring is faulty until all control module DTC memories have been interrogated.

VAG 1551 Scan Tool
- The display group numbers will be 3 digits from July 1996 (up-to-date VAG 1551 program card).
- From July 1997 a further number on the right next to the DTC will be displayed/printed-out when interrogating the DTC memory (up-to-date program card version of VAG 1551). This number indicates the type of malfunction, which is also given again in text under the affected component.

On Board Diagnostic (OBD) Technical Data

Memory
- Permanent memory yes
Data output
- Rapid data transfer yes
Data transfer between
the control modules via:
- CAN-Bus yes
Output Diagnostic Test
Mode (DTM) no
Coding control module no
Reading measured value block yes
Electric/electronic components
and locations