Description of On-Board Diagnostics

GENERAL INFORMATION
A self-diagnosis feature with fault memory is built into the transmission control unit to allow specific faults within the electronic Tiptronic control to be detected and stored.

To prevent detected and stored faults from being erased when the ignition is switched off, a permanent positive voltage is present at the control unit.

Detected faults remain stored in the fault memory for at least 50 engine starts.

CAUTION: If the connector is pulled off the transmission control unit or if the battery is disconnected, the fault memory is erased.

If terminal 15 becomes inoperative, the system enters the "emergency mode". The fault warning lamp does not light up in this case.

In "emergency mode" and if diagnosis wires are faulty, the diagnosis program cannot be entered.