01M Transmission
ON-BOARD DIAGNOSTICS, GENERAL INFORMATIONFunction
The automatic transmission is controlled electro-hydraulically. "On Board Diagnostic" (OBD) capability refers specifically to the electrical and electronic controls.
The Transmission Control Module (TCM) -J217- receives information from components that affect selection of gears, and passes the information on to solenoid valves that control the valves in the valve body.
The TCM 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 cause can be determined quickly. Malfunctions are recognized by electrical signals and stored in the DTC Memory.
Functions of Transmission Control Module
Malfunctions in the monitored sensors or components are stored in the DTC Memory along with an indication of the type of malfunction.
Malfunctions that only occur once become sporadic (temporary) malfunctions. Sporadic malfunctions are also coded as such.
The Transmission Control Module analyzes the information and distinguishes different types of malfunctions. Those that do not reoccur within 5 to 20 km (3 to 12 miles) or within 6 to 24 minutes are stored as sporadic malfunctions. Refer to DTC table. Testing and Inspection
Functions of the VAG 1551 Scan Tool
Electrical malfunctions that affect vehicle performance can be identified with the Scan Tool (ST) VAG 1551. The On Board Diagnostic capabilities can only be fully exploited using operating mode 1 ("Rapid data transfer").
Transmission Control Module Function Chart:
Refer to image for the list of selectable functions that the Scan Tool VAG 1551 can register.
Transmission Control Module safety functions
If critical malfunctions occur while 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 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 selector lever is in position "D", "3" or "2" then 3rd gear is activated hydraulically until the malfunction is repaired.
If there are malfunctions which can lead to emergency running, the transmission will remain in the emergency running mode until the malfunction is no longer recognized by the TCM over a predetermined period.
Malfunctions that may activate emergency running mode
Open circuit in wiring, short-circuit, electrical or hydraulic components faulty.
Transmission Control Module recognition of malfunctions
If a malfunction exists, it is stored as a static malfunction. If the malfunction no longer exists after a predetermined period or distance travelled, it is considered a sporadic malfunction.
Malfunctions that are stored in the DTC Memory as sporadic malfunctions will be displayed as such when retrieved by the Scan Tool VAG 1551. In such cases, "SP" appears on the right of the display. If the printer is switched on, "sporadic DTC" is printed out after the malfunction is addressed.
Malfunctions which are stored in the DTC Memory as sporadic malfunctions are automatically erased after 1,000 km (600 miles) or 20 hours driving time.