Corrado Storm Posted January 8, 2011 Report Share Posted January 8, 2011 I've just bought an Audi A3, and thought I had a simple problem of a defective Hazard Warning Switch which remained illuminated perminently (i.e. didn't switch-off after the normal time dealy). However, I've now removed the switch, and I think the problem may be the car not going into 'sleep mode' properly. The interior lights & mileage all turn-off when you lock the car, however, having sat inside the locked car I can now hear electrical 'buzzing' from behind the central dash area suggesting some items are remaining live - explaining may battery drain after a couple days of non-driving. Not really familiar with CAN-bus wiring, but having looked at the Hayes wiring diagram there seems to be a 'Convenience CAN Bus' link to the 'On-board supply control unit'. I'm guessing that the supply control unit is staying live when it should be 'asleep' which is why the Hazard switch is illuminated. Does this make any sense? Any suggestions on what I should try next? :confused: Link to comment Share on other sites More sharing options...
PetrolDave Posted January 8, 2011 Report Share Posted January 8, 2011 Get a full scan done with VAG-COM and see what fault codes are shown, if there's a problem with one of the CAN buses or any of the modules that will show it up. Link to comment Share on other sites More sharing options...
Corrado Storm Posted January 9, 2011 Author Report Share Posted January 9, 2011 I've actually traced the problem to the 'Welcome Home' light switch, the one below the main light switch which holds the sidelights on for 40 seconds after you lock the car. This switch was remaining illuminated perminantly along with the Hazard Switch. Disconnecting the connector from the back of this switch has cured all other symptoms, and the car now powers-down and goes into sleep mode properly after the normal delay! I don't use this switch/feature so will probably not bother to replace it, just leave it disconnected. Link to comment Share on other sites More sharing options...
teerak2uk Posted January 10, 2011 Report Share Posted January 10, 2011 Like Dave said i would personally still have a scan done as the fault may well be coming from else where making the home light stay illuminated Link to comment Share on other sites More sharing options...
PetrolDave Posted January 13, 2011 Report Share Posted January 13, 2011 IIRC the coming home switch connects to the central convenience module which also uses inputs from light sensors - so maybe the fault lies there? A VAG-COM scan is the way to find the root cause, you may well have dealt with a symptom and left the root cause still there. Link to comment Share on other sites More sharing options...
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