General System Description

FUNCTIONS
Automatic transmission 01N operates by electro-hydraulic control. The Transmission Control Module (TCM) receives input signals from those components that affect gear selection, and delivers output signals to solenoid valves that control gear selection in the valve body.

The "On Board Diagnostic" capability refers specifically to the electrical and electronic controls. In the event of an electrical or electronic malfunction or an open circuit, the cause of the malfunction can be determined quickly.

TRANSMISSION CONTROL MODULE (TCM) OPERATION
The TCM is equipped with Diagnostic Trouble Code (DTC) memory. If malfunctions occur in the monitored sensors or components, they are recognized by the TCM and stored as DTCs in DTC memory, along with an indication of the type of malfunction.

For a summary of scan tool functions, refer to Powertrain Management.

The TCM evaluates the information, distinguishes different types of malfunctions, and stores these as DTCs until DTC memory is checked and erased using the scan tool

MALFUNCTION RECOGNITION
If a malfunction exists for a certain time, it is recognized and stored as a static malfunction.

A malfunction that is recognized once, and does not occur again within a specified period, is identified as a "sporadic" malfunction, and coded as such.

Sporadic malfunctions are identified by an "/SP" designation on the scan tool display when checking DTC memory. If the printer is switched on, a "sporadic DTC" designation is also printed.

"Sporadic" malfunctions that occur but are not recognized again are automatically erased after 40 cold starts (with warm-up)

The On Board Diagnostic (OBD) program can be carried out using the VAG 1551 or 1552 scan tool, or a Generic Scan Tool (GST) and address code 33.

TRANSMISSION CONTROL MODULE (TCM) BACK-UP MODE
If certain critical malfunctions occur while driving, the transmission continues to operate, but switches to a "back-up" mode.

If the malfunction occurs in a forward gear, the back-up mode selects 3rd gear. The vehicle can also be driven in transmission ranges "1," "2," "3" and "R" while in the back-up mode.

If the malfunction occurs while the selector lever is in position "1," "P." "N" or "R." the back-up mode for that gear selection is activated.

When a malfunction triggers the switch to back-up mode, the transmission operates in that mode for as long as the ignition remains switched on.

During subsequent operation of the vehicle, if the selector lever is in the "D," "3" or "2" position and the malfunction occurs again, 3rd gear will remain hydraulically activated until the malfunction is repaired.

MALFUNCTIONS THAT ACTIVATE BACK-UP MODE





ON BOARD DIAGNOSTIC (OBD) CAPABILITY
Causes of electrical malfunctions that affect vehicle operation can be determined using the VAG1551 or VAG1552 scan tool.

OBD capabilities are only accessible using the VAG1551 or VAG1552 scan tool in "Rapid data transfer" operating mode 1, connected to the TCM via the Data Link Connector (DLC).






WARNING:
^ When driving or riding in an airbag-equipped vehicle, never hold test equipment in your hands or lap while the vehicle is in motion.
^ Objects between you and the airbag can increase the risk of injury in an accident.

MALFUNCTION INDICATOR LAMP (MIL), FUNCTION
If transmission malfunctions that affect exhaust emissions are recognized by the TCM, the Malfunction Indicator Lamp (MIL) will be switched on.

Critical malfunctions are indicated immediately by the MIL. Less critical malfunctions are indicated if they occur during two successive "trips. "

MIL FUNCTIONAL CHECK
Switch ignition on (engine not running).
- MIL must light up

Start engine and let idle.
- The MIL must be switched off after several second.

If the MIL does not light up when ignition is switched on:
- Do not start engine.
- Check wiring according to wiring diagram, and/or replace MIL light bulb.

If the MIL does not go out after the engine is started:
- Check DTC memory.

RECOGNIZING A "TRIP"
After the ignition is switched on:

All exhaust emission-related OBD functions (for malfunction recognition) must be checked one time.

TCM must recognize the minimum driving distance of 10 km (6 miles). In the event of a sensor malfunction, the replacement value is 10 minutes at driving speed.

ATF operating temperature must reach at least 75°C (167°F). This requirement does not apply if the transmission fluid temperature sensor is faulty.

If an exhaust emission-related malfunction is recognized, the "trip" is recognized as complete.