Component Tests and General Diagnostics

Central Locking System (vehicles Without Power Windows), On Board Diagnostic (OBD)

Functional description

The locking units located in the doors (door lock) have an electric motor.

The motor locks the door and also takes care of the "Safe" condition, i.e. after locking at an external lock (door lock, tailgate, radio remote control) the vehicle is protected against theft and can no longer be unlocked from the interior. The feedback on the respective condition in control unit occurs via the contact switch in the locking unit.

All the known convenience functions can be performed with the electric convenience system, interior lights control, ATA with interior monitoring and the radio remote control

If the airbag control unit is triggered, a signal is sent to the convenience control unit to unlock the doors.







The central locking control unit (J379) is located under the dash panel and is secured by a bracket to the steering column. It is equipped with a DTC memory. The On Board Diagnostic (OBD) connection is located under the driver's knee bar to left of the steering wheel.

The control unit detects malfunctions in the central locking system and stores them in a permanent memory.

To commence troubleshooting, initiate self-diagnosis and retrieve the stored information with the scan tool VAG 1551.

System tester VAG 1552 may also be used.

The malfunction information displayed is used to refer to a DTC table with notes on the possible causes for directed repair measures.

Malfunctions which can be attributed to a temporary open circuit in the wiring or a loose contact, will also be stored. These malfunctions will be displayed as sporadic DTCs "SP".

Determining the items which have possibly triggered the anti-theft alarm system

The breakdown of the display content illustrated for the display group number 10 gives information as to which component triggered the alarm system last, and can therefore help the troubleshooting/rectification. Evaluating Measured Value Blocks

This "DTC memory" cannot be erased. Only statistical malfunctions are considered:

- Central locking inoperative
- Mirror positioning motor inoperative
- Electric window positioning motor inoperative
- CAN communication inoperative


NOTE: Before changing a component erase DTC memory, perform functional checks and check DTC memory again.