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03 A4 Trunk will only open by the manual key

1K views 17 replies 3 participants last post by  Billthebuilder 
Hello everyone,
I just purchased this vehicle and none of the buttons work to operate the rear trunk. they are not making any noises at all in the back. From what I can tell there is a button in the driver side door panel and also at the trunk itself but they do not work. I checked the fuses and they all look good. what other components should I be checking to get these buttons to work? is there a relay or something I am missing?
Thanks in advance for your time!

Tpotter
Remove the trunk liner on the lid and check the actuator 2 tork screws unplug it and it’s easy to bench test.
 
I agree, but why would both the driver door switch AND the switch at the trunk not operate? 🤔. i checked all of the fuses, on the driver side dash, of what i thought it could be and all of them looked good.
Fuse is #35 if that’s not it it could be one of the relays located under the dash panel. Check if you have Voltage to the switch
 
I checked every fuse in the panel and they were all in good condition.
Tried to find the relay for that function but can’t figure it out. Is there anything else not working? There is a multi function relay listed but I’m unsure what it includes. I would still check the continuity of the door switch.
 
no i sure haven't....unfortunately i have been chasing down a no crank issue, which turned out to be the starter relay, and a coolant leak, which is a stripped bolt that is supposed to be holding the rear coolant flange on. ill try to get back to the door switch soon.
One thing at a time eventually you’ll have a good car!
 
Ok finally back at trying to figure out the trunk situation. I have noticed that, at times, when i turn the headlights on the trunk will pop open. But its never consistent. I have also found that There are some wires spliced from the tail lights and looks like they are providing power to the license plate lights. There are also wires that seem to be spliced into a trailer light towing module. It also has some goofy factory sounding alarm that goes off when i turn the key to the right in the driver door and lock the car doors.
How would i go about checking for voltage at the driver door switch? Is there a certain pin or wire that should have 12v? And also same questions at the trunk switch?
I would search for a schematic and try and un do any alterations from the add on alarm and the brake/ tow lights. Seems the PO did not do things proper and this could be the root of the problems
 
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