Technical product information: Water ingress in the plug of the engine control unit in the Grand California
Volkswagen has published a Technical Product Information (TPI 2075254/1) that deals with possible water ingress in the engine control unit connector of the VW Grand California. This can lead to error messages in the instrument cluster and requires a specific repair measure.
Problem definition
Some owners of a Grand California are reporting warning messages on the display. The workshop has found that water has collected in the engine control unit connector. This is due to insufficient sealing of the splice connection (junction 179) in the wiring harness.
Technical background
Inadequate sealing can allow moisture to penetrate the T91a plug connection (pins 1, 2 and 4) of the engine control unit via the earth cables. This causes corrosion and electrical faults, which manifest themselves in error messages.
Solution & repair measure
The workshops will carry out the following steps to rectify the problem:
1. check the plug: The affected plug is checked for moisture and corrosion.
2. expose the splice connection: The wiring harness in the engine compartment is opened to expose junction 179.
3. replace corroded cables: If corrosion is present, the affected cables are shortened and reconnected.
4. sealing with butyl cord: A new watertight seal is created with butyl rings and a special shrink tube.
5. repair the plug and control unit: If necessary, the engine control unit and the connector housing are replaced or repaired.
