General Information

On Board Diagnostic (OBD)

Function
The Transmission Control Module (TCM) -J217- for the automatic transmission is equipped with a Diagnostic Trouble Code (DTC) memory.

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

Malfunctions which occur only occasionally are known as sporadic malfunctions and are coded as such.

The Transmission Control Module (TCM) -J217- for the automatic transmission analyses the information and distinguishes different malfunctions and stores them. VAG Codes

If malfunctions do not reoccur within:
- min. 5 km (3 miles) or 6 minutes or
- max. 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 (ST).

The possibilities offered by OBD can only be fully exploited with operating mode 1 "Rapid data transfer" of VAG 1551 Scan Tool (ST).

Functions which the VAG 1551 Scan Tool (ST) can register. Selectable Functions When Using VAG 1551/1552 or VAS 5051

Safety functions of Transmission Control Module (TCM)
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", 3rd gear emergency running mode is activated.

If the malfunction occurs in "1", "P", "N" or "R", the emergency running mode for that stage is activated.

If the engine is started again in the emergency running mode and the malfunction occurs with the selector lever in "D", "3" or "2", Third Gear is activated hydraulically, until the malfunction is repaired.

If malfunctions exist which result in emergency running, the transmission remains in the emergency running mode until the ignition is turned off.

Malfunctions which may activate the emergency running mode:
Open circuit in wiring, short-circuit, malfunctions in electrical or hydraulic components.

Transmission Control Module (TCM) malfunction recognition
If a malfunction exists for a certain time, it is stored as a static malfunction. If the malfunction no longer exists after a pre-specified time or distance, it is stored as a sporadic malfunction.

These malfunctions which are stored in the Diagnostic Trouble Code (DTC) memory, will be displayed as "sporadic malfunctions" when retrieved by VAG 1551 Scan Tool (ST). "SP" appears on the right of the display in such cases. If the printer is turned on, "sporadic malfunctions" are printed out after the malfunction is addressed.

Malfunctions which are stored in the Diagnostic Trouble Code (DTC) memory as sporadic malfunctions are automatically erased after 1,000 km (600 miles) or 20 hours.