Salvage P85D trunk latch issue. HELP!!

[MoGosh]

Hi all so several months back i baught a salvaged p85d with pretty bad rear end damadge I've got the car looking beautiful and driving as it was intended. I've had one problem in the repair process that no one has yet been able to figure out. I'm hoping you guys might be able to shed some light.

Once everything is plugged in the liftgate closes when pushed down but the trunk latch just releases right away. When I disconnect the electronic connection into the latch it closes When pushed down no problem except it will obviously no longer open unless I crawl into the trunk and pull the manual release.

I've tried changing the trunk latch itself as well as the trunk latch actuator which is found above the trunk latch and connects into it but this has been to no avail. I'm guessing there is a sensor somewhere telling the latch to release when it's plugged into the car but I cannot figure out where this would be coming from. This is further supported becaude the power loftgate button when pressed opens thr trunk but does not close it. I was reading some posts where some mentione that there is a pinch sensor and I thought maybe the car senses an obstruction so it releases the latch but I cannot find a pinch sensor in the repair manual or anywhere in the trunk. Also I'm not sure if maybe the power liftgate module has anything to do with this issue and may need go be replaced.

Thanks

 

[NiallDarwin]

Hi MGosh, thanks for posting this question.

I have a similar issue, but not quite as bad. My car will power open the auto trunk but will not power-close. It beeps twice when I press the button but does nothing. If I force the trunk closed and latch it firmly it remains closed but if I close it softly it automatically opens again.

My car had its tailgate removed for repair. I have heard that some of the computers need re-configuring after components have been disconnected.

I was able to look at a service manual to try to understand the issue. It showed the struts, the latch, the release and the control unit (which is under the carpet behind the rear right wheel arch). It did not show any sensors (that I could find). I also didn't note a mention of resets/reconfigurations but I wasn't specifically looking for that.

Stripping the lining from the tailgate (trunk door) and the carpet of the trunk I can find no sensors but there is a stripped wire as if someone tore something off when removing the trim during its repair. I can't see what it should have been connected to but I'm guessing its an option I don't have - a light or speakers perhaps.

So my questions are:
1 Where are the sensors for the automatic trunk?
2 Do the computers need re-setting if the tailgate / trunk door has been removed and then reconnected?
3 Is there a possibility that I'm missing an important component?

Thanks.

 

[MP3Mike]

That sounds like it thinks it has hit something while trying to close so it reverses. Maybe one/both of the struts got damaged?

 

[NiallDarwin]

Thanks Mike. Do you know if the sensors are in the struts or somewhere else?

 

[MP3Mike]

I'm not positive that there are actually sensors. I think it just measures that amount of force that has to be applied to close the hatch. So if it suddenly starts drawing more power to close it thinks it has hit something...

 

[NiallDarwin]

That makes sense. So that's potentially questions 1 and 3 answered. Hopefully an answer to 2 will be provided by the community too

So my questions are:
1 Where are the sensors for the automatic trunk?
2 Do the computers need re-setting if the tailgate / trunk door has been removed and then reconnected?
3 Is there a possibility that I'm missing an important component?

Thanks.

 

[Drewflux]

The linear actuators aka struts do have positions sensors in them. It sounds like some sort of jam protection mode, telling tge control module something is in the way of the tailgate when closing. Not sure of the reset procedures

 

[KalJoMoS]

Crossed to this while searching and if it’s any use for someone in future there seems to be some kind of feature in the latch to mate with striker part. This is the part from manual.