passat tdi battery drain

[andycampers]

i i have just bought a passat 1.9 dti diesel s reg .it starts first time runs ok but if i leave the battery connected to the car overnight it goes completly flat. the battery is fine have checked it myself . i am a mechanic so drop tested it its ok. i have tried everything but to no avail. i think it may be ecu related but i hope not. it goes completly flat if i lock the car or not. there are no lights being left on checked the usual boot light etc .radio not being left on.when i connect the battery up there is a very slight spark at the terminal even though everything is turned off.as i connect the battery up there is a solenoid clicking on inside the diesel pump then after a few seconds it clicks off battery still connected up. if i turn on the ignition on it will fire up and run ok.but when i turn the ignition off the engine stops as it should. however when i disconnect the battery terminal i can hear the diesel pump make a slight click and there is very slight spark at battery terminal.if i then connect it back up to battery it will click back on at pump then a few seconds later it will click off. if i leave the battery connected now it wont go flat . but if i turn ignition on then off and leave battery connected overnight it will be completly flat next day not even a volt. a fellow mechanic suggested removing the carpet on passenger side of car and completly drying it out .i have done all this but still the mystery remains.can anybody suggest anything that may help thanks andy

[a8 tech]

Hello andy,open the bonnet and click over the bonnet lock so it thinks its closed,now lock the car and leave it for two hours and then connect to the earth lead of the battery a amp clamp and look at the reading.The reason for two hours is the can bus system needs to close down completely,you should be looking at a resding off 0.0030 miliamps.If the reading is higher then remove the fuses on the main fuse box one by one until reading drops to specification(so open all doors and click over the locks to continue)and again allow 2 hours for system to settle.If your getting 1.00 amp then its likely to be a door,if you open the door lock with the amp clamp connected you will see the spike so you can get a good idea what current draw to expect from certain consumers.The water ingress issue that occurs to the nsf footwell from the poor pollen filter seal is always a good place for resistive wiring problems.Good luck this type of fault can be easy or very hard to locate.If you find by removing a fuse the current dops then look what circuit that fuse powers and isolate the consumers

[andycampers]

Hello andy,open the bonnet and click over the bonnet lock so it thinks its closed,now lock the car and leave it for two hours and then connect to the earth lead of the battery a amp clamp and look at the reading.The reason for two hours is the can bus system needs to close down completely,you should be looking at a resding off 0.0030 miliamps.If the reading is higher then remove the fuses on the main fuse box one by one until reading drops to specification(so open all doors and click over the locks to continue)and again allow 2 hours for system to settle.If your getting 1.00 amp then its likely to be a door,if you open the door lock with the amp clamp connected you will see the spike so you can get a good idea what current draw to expect from certain consumers.The water ingress issue that occurs to the nsf footwell from the poor pollen filter seal is always a good place for resistive wiring problems.Good luck this type of fault can be easy or very hard to locate.If you find by removing a fuse the current dops then look what circuit that fuse powers and isolate the consumers

thanks i ncant see it being a door lock as the battery drains with the doors locked or unlocked.i have tried all the relays from another passat but still the same .like u say its going to be hard to find cheers andy