Hi have an issue where the upper tailgate stops closing when the lower tailgate latches which I think is due to one of the lower tailgate anti-trap sensors triggering or the microswitch in the latch not making contact as the tailgate completes closure. Searched and used advice and docs on the site so have checked what I can and tried recalibrating.
Does anybody know how to test individual anti-trap sensors? I suspect one of them is faulting as the lower tailgate closes but not sure if these are just pressure switches or more sophisticated - manual suggest they are hall effect ? Idea is to test them manually and see if they trigger as the tailgate close. Cheers Richard

I believe they are torque variant motors. So, something gets trapped and the relevant amount of torque reverses the motors? Buy I could be completely wrong in my assumption…

Craig 👍

I had a similar but different problem - but the process will be the same. That is, buy an ODB code reader & see what fault codes are being generated. That will point you in the right direction. You can also read the real time values from the sensors if required.

The relevant thread is here

Not sure how if all model years have them, but pretty sure the later model years have the anti trap sensors in the sides of the upper tailgate.
Been a while since checked one, but as soon recall it’s on both sides of the upper tailgate built into the seal/ trim running down both side next to the glass. If you squeeze/ squash the seal / trim it should stop tailgate.
You can maybe ( carefully) try this to check it has them. I have seen them fail before, also worth checking. if your tailgate is not aligned centrally it can cause it to trigger the sensor and not close tailgate. Hope it helps.

Agree - the anti-trap on the lower tailgate should cause that to re-open - or in my case, not even try to close. There may also be a sensor that checks the lower tailgate is fully closed and it sounds like that's the case to me. Then there's anti-trap on the upper tailgate.

A code reader is the only way to really tell what the issue is.

You could maybe try closing the lower tailgate manually and giving it a good push ?

M11buc wrote:

If your tailgate is not aligned centrally it can cause it to trigger the sensor and not close tailgate. Hope it helps.

Thanks all for your advice and insights - all really helpful. I tested each anti trap sensor individually by starting the tailgates closing and squeezing the strips. All work fine one needed glueing back in place, nothing fowling them or any damage.

Per M11buc’s note I am tending to think it is a lower tailgate alignment issue and the latch close sensors not in sync as the RHS closes fractionally just after the LHS as the soft close takes up.

Await the return of my icarsoft (it’s just had a busy shift on my nephews Disco4 ) and shall investigate further. Will let you all know to close the thread and for info to help others. Cheers Richard

Cam-Tech-Craig wrote:

I believe they are torque variant motors. So, something gets trapped and the relevant amount of torque reverses the motors? Buy I could be completely wrong in my assumption…

Craig 👍

Well a few days ago using the spare wheel removal system
I stupidly forgot to remove the clamp from the upper gutter and closed the tailgate.
Fortunately it stopped on contact and re-opened itself, so it must also have some sort of torque motor sensing! 2018 SE SDV8 4.4 Byron Blue

Also in the WS manual section 501-03 there is a 60 page troubleshoot guide for upper and lower tailgate 2018 SE SDV8 4.4 Byron Blue

Check out this, it maybe the problem, maybe not but it's a free check...!!

https://www.fullfatrr.com/forum/topic66566.html Pete
__________________________________________________
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To close this one off:
The diagnostic scanner did not find any DTC fault codes and all the sensors and latches checked out ok. I then set about recalibrating the upper and lower tailgates by cycling manually then performing the height calibration in the upper tailgate. Still same problem, upper tailgate stopped closing on auto as soon as the lower tailgate closed and latched. What I did notice though was although I calibrated the tailgate at the limit if it’s upper travel, it would only raise to around 50mm off the upper limit. I then went through the same process to calibrate it all with the Engine running and now works perfectly and both tailgates close via the fob and dashboard button. No DTC fault codes so can only assume it is voltage related. New batteries were fitted last month and BMS was updated. Will see what happens next I guess and if the car drops the calibration again. Thanks for all help above. I also found this article very useful if anybody else is having similar - issues.

https://static.nhtsa.gov/odi/tsbs/2014/SB-10071772-6903.pdf

Good news & hopefully a permanent fix

Richiesrangey wrote:

Thanks for all help above. I also found this article very useful if anybody else is having similar - issues.

https://static.nhtsa.gov/odi/tsbs/2014/SB-10071772-6903.pdf

Great research and sharing of your problem-  2018 SE SDV8 4.4 Byron Blue