2014-06-08 born_slippy found the same wires in the battery compartment so one doesn’t have to open up the trunk trim to do this.
Yellow/WhiteGreen/White wire from convenient module is the same wire as trigger/green wire at the latch.
convenient module plug
Yellow/Green wire from motor plug is the same as the switch button (GREEN) and brown is any brown wire as ground
We have 2 cars that have motorized trunk lid, we want to close the trunk lid with the door button or the remote since they’re not options on both of our Q7 and A8L. We tried with the A8L first and it seems to work well.
According to my findings:
1. When we push the door switch or the remote to close or open the trunk, the latch wires (3 pins: Green, Brown and White/Black), Green and Brown pulses 12V between them – this will be the trigger for our relay coil.
2. When the trunk is opened, the close switch (black rectangular button on top of the trunk lid) with 4 pins: White/Red, Green, Brown, Brown: White/Red will be 12V and 0V when the latch is in the close position. When we push the button, the 2 center pins = Green and Brown will short to each other as long as the button is pushed.
All we need is a relay that triggers at 10-14v. The trigger input positive should be connected to the Green wire on the trunk latch. The negative should be connected to the brown wire – leave the black/white wire alone.
The outputs of the relay(open then short when activated) should be connected to pins 2 and 3 (center 2 pins) of the close switch.
When you buy a relay – the coil will have pin # and sign + and -, the positive (+) pin of this coil goes to Green and negative (-) pin goes to Brown.
The relay PIN B and A go to 2 center pins of the switch (Pin 2 & 3) doesn’t matter which color because A will short to B when the coil is activated (the first relay picture – SPST).