Automatic Transmission 096 With On Board Diagnostics (OBD)

AUTOMATIC TRANSMISSION 096 WITH ON BOARD DIAGNOSTICS (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 and components, these are stored in the DTC Memory together with an indication of the type of malfunction.

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

The TCM analyses the information and distinguishes different malfunctions and stores these until the DTC's Memory contents are erased.

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

The possibilities offered by OBD can only be accessed with operating mode 1 "Rapid data transfer" of the Scan Tool VAG 1551.

Safety functions of Transmission Control Module (TCM)
If critical malfunctions occur when driving, the transmission continues to operate in the emergency running mode (Limp Home). If the malfunction occurs in a forward driving range, 3rd gear (3GR) is activated by the emergency running facility. It is also possible to select the driving ranges "1", "2", "3" and "R" in the emergency running mode (Limp Home).

If the engine is started again in the emergency running mode (Limp Home) and the malfunction occurs, 2nd or 3rd gear (3GR) is activated hydraulically - if the selector lever is in position "D", "3" or "2"- until the malfunction is corrected.

If malfunctions exist which result in emergency running, the transmission remains in the emergency running mode (Limp Home) until the ignition is switched off.

Malfunctions which may lead to emergency running:
Open circuit in wiring, short-circuit, control module or solenoid valves faulty.

Notes on DTC recognition:
If a malfunction exists for a certain time, it is stored as a static malfunction. If the malfunction no longer exists for a certain time, it is considered a sporadic malfunction.

Malfunctions which are stored in the Memory as sporadically occurring, are displayed as sporadic malfunctions" only if the malfunctions are retrieved with the Scan Tool VAG 1551. "SP" appears on the right of the display in such cases. If the printer is switched on, "sporadically occurring malfunction is printed out after the malfunction is addressed.