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So the past few months my trunk would not unlock either with the key or by pressing the button on the trunk lid. It wasn't a big deal, the 2-3 times I need it I crawled back and opened from the inside. I planed on getting around to researching/fixing it but now about every 2nd or 3rd time I start my car it opens the trunk...I have to jump out and open/close it before I drive away.

Any ideas what gremlin is causing this?
 

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This is what the system looks like:



4/103 receives the remote signal and tells the CEM to open the lock.

So, if that doesn't work AND the trunk switch doesn't work AND the lock works because it opens every now and then...
Then maybe the CEM is bad?

Still, I would check the wiring for the trunk lid. Check the loom where it exits the body and enters the lid (where it flexes), to make sure you have no split/frayed wires.
 

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Also: if the CEM sends an "open" command to the lock, it should receive a confirmation signal from the lock motor. Otherwise a DTC is triggered. Another reason to distrust the CEM.
 

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I would replace the trunk harness first. It sounds like it is getting triggered to open with the vibration on the car. It would make sense if it's looking for a signal and then opens if the wire is shorting and it "thinks" it's getting a signal when it vibrates into the the car. Harness is on the bottom side of the top of the trunk. Easy to spot - only one.

Easy test - buy some of those DOOR edge protectors from walmart - put it around the square where the harness loops around and that'll keep it from contacting the metal and short circuiting. In theory should solve your problem in the future as well. I just routed my wires a bit differently to prevent it from happening again - they are much more easily snagable if I push a full size box in the trunk but otherwise, it doesn't rub on that spot anymore.
 

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So the past few months my trunk would not unlock either with the key or by pressing the button on the trunk lid. It wasn't a big deal, the 2-3 times I need it I crawled back and opened from the inside. I planed on getting around to researching/fixing it but now about every 2nd or 3rd time I start my car it opens the trunk...I have to jump out and open/close it before I drive away.

Any ideas what gremlin is causing this?
Wire harnesss number one issue. I did this just last month on daughter's car. Volvo harness costs about U$42. Glück.
 

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Right - the open/close signal from the latch is a LINbus message, but the servo is energized by plain old grounding of a return line, within the CEM. A short will trigger it just as easily.
 

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I have the same exact issue. Sometimes hatch will not respond to switch or remote commands. Other times it pops on its own, ESPECIALLY at Key On / Off events. I know for a fact this car had a water ingress issue where the CEM got wet. There were other issues, mostly phantom blower motor activity and general misbehavior. After some months of drying out, all CEM related symptoms pretty much faded away. But the hatch pop issue seems to reoccur in response to weather/temperature and possibly long durations of the car sitting unused.
 
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