Disco 4 (LR4) Tailgate intermittently won’t open - fixed

I’ve found a two-wire connector (3007/8) under the passenger seat that handles the upper and lower tailgate actuators. No output on the upper side.

It looks like the driving FET is dud. Next stage is either remove the BCM and attempt a board repair, or rig up a separate system.

Fixed.

It was the actuator. Apparently it draws excess current as it fails, triggering an overcurrent lock-out in the BCM (but no error codes or indications that this is happening).

Hi, just signed up to reply to this thread. I'm having EXACT same issue and similar troubleshooting but didnt get as far as you...
1) Tailgate intermittently works
2) In trying to diagnose, switch was working, no voltage was being supplied (or maybe there was I can't remember), 12V external to actuator was making it work.
3) Ended up realizing that disconnecting and reconnecting battery would fix it.
4) Eventually, that stopped working, but sometimes starting and stopping engine would make it work.
5) I'm also having 'tailgate open' errors when it's closed - alert pops up when i've started the car after tailgate stuck, then message disapears, then it opens.
6) I also get 'key notfound' errors but I've always had them.

My battery is also on the way out - its a non-AGM and goes flat easily if i leave a light on for 15 minutes or so.

I just wanted to confirm, did your actuator fix all the issues, or did you end up having to do something else? I've already ordered a new AGM battery (mainly for the obvious battery reasons) but was curious if new battery would fix some of these issues before I also buy a new actuator.

Cheers.
Matt.

Yes @mattyjee the new actuator fixed it.

Resetting the system sometimes works because of the overload shutdown mentioned above.

mattyjee said:

Hi, just signed up to reply to this thread. I'm having EXACT same issue and similar troubleshooting but didnt get as far as you...
1) Tailgate intermittently works
2) In trying to diagnose, switch was working, no voltage was being supplied (or maybe there was I can't remember), 12V external to actuator was making it work.
3) Ended up realizing that disconnecting and reconnecting battery would fix it.
4) Eventually, that stopped working, but sometimes starting and stopping engine would make it work.
5) I'm also having 'tailgate open' errors when it's closed - alert pops up when i've started the car after tailgate stuck, then message disapears, then it opens.
6) I also get 'key notfound' errors but I've always had them.

My battery is also on the way out - its a non-AGM and goes flat easily if i leave a light on for 15 minutes or so.

I just wanted to confirm, did your actuator fix all the issues, or did you end up having to do something else? I've already ordered a new AGM battery (mainly for the obvious battery reasons) but was curious if new battery would fix some of these issues before I also buy a new actuator.

Cheers.
Matt.

Click to expand...

hi , welcome to the asylum, lol

if u don’t mind me adding and not wishing to try and teach u how to suck eggs, but plse fully charge ur new battery before fitting and then once fitted reset ur BMS with diagnostics so the system will then know a new battery has been fitted

may I also ask do u have ur own or access to a code reader plse as that will also help considerably

Fingers crossed it sorts out the issues ur having , if not , plse let us know

Hi All, I would like to ask for help on this topic please. I have a problem with the upper tailgate not releasing on my Disco 4 2010 MY. The upper tailgate became unopenable using the usual micro switch on the pull handle a few weeks ago. It was an intermittent issue for a few openings and then it failed completely. I released the tailgate using the release button on the key fob and this still continues to work no problem. Since the failure, I have replaced the micro switch (although subsequent testing showed no fault) and the main release unit in the lower tailgate (although this showed no signs of a fault when I checked it on the car using the key fob button) but having replaced both units with new items the pull handle switch still fails to operate the lock in the lower tailgate (I have tested the new micro switch and it is good). I'm thinking fuse or control unit but am unable to find anything on forums beyond the switches etc. I have the electrical wiring diagrams and have checked fuse 20P which I think serves the tailgate. I also have a code reader and the vehicle is completely clear of any DTCs. Does anyone have any ideas as to where I could go next? Any help would be gratefully received as it is bugging the hell out of me.

If you’ve replaced the input (switch) and output (actuator), then the next step would be checking the wiring, especially the connector under the passenger seat as mentioned above. I traced everything back to the BCM, which is behind the glovebox.

Beyond that, battery change or hard reset?

Thanks for the help guineafowl21. Can I ask a couple of questions: WRT the BCM did you find any fault with it? Did you need to replace it? WRT the connector under the passenger seat was a wire(s) disconnected? Did you need to make any sort of repair i.e. push the connector back together or repair a damaged wire? Many thanks.

No, BCM was fine, but according to my GAPIID it was reporting tailgate activation, but not sending the signal, as confirmed by multimeter. This was due to an overcurrent lockout unseen by the scan tool. It was the actuator failing that caused the fault.

Connector under the seat was fine.

Many thanks @guineafowl21. I disconnected both leads from the battery for 15 mins & followed up by connecting the pos & neg together directly (is that the correct procedure for hard reset?) but to no avail. The tailgate ajar switch state is shown as on when open and off when closed so that seems to be OK which I assume is going to/from the BCM. I tried checking switch status activity when pressing the key fob release button but that didn't show anything. Have checked batt voltage (12.7 engine off) via OBD port so looks OK but state of charge is shown as low(ish) around 70% so batt now on charge. Will have to wait a few hours to see if it gets to 100%. Batt was replaced by dealer 5.5 yrs ago with genuine LR part.

The switches also rot out under the rubber push gaiter in the tailgate handle.

Thanks @lynall. I replaced the switch with a new one - tested it as well so I know it's OK.
Batt now charged to 99% - still not working. Will have to do some more thinking.

Hi all, does anyone know if the FET (Field Effect Transistor) that is part of the BCM that operates the upper tailgate release has any other functions that would indicate that if it had failed then something else would also not work?

Hello All, Problem now fixed. I've returned to this thread to explain how I have now (today and somewhat belatedly) fixed my upper tailgate not opening issue which may help someone else. Having tried all the fixes proposed on this forum (many thanks to everyone for the suggestions) and not fixed it I eventually took it to my local L/R Indy specialist who has always been pretty good at sorting things. However, on this occasion he wasn't able to sort it as in his experience (bearing in mind I'd already replaced both the switch and the lower tailgate actuator) it is often the wiring inside the pull handle that fails but he was unable to remove the handle as the 4 lower fixing bolts couldn't be removed as they were rusted in to the brass inserts in the plastic body causing them to rotate. He would normally end up destroying the pull handle to get it off the car - so new replacement needed at £450 plus labour! I decided to take a 2nd look at this myself and decided to carefully drill out the bolts to facilitate removal of the handle from the car with no damage and also protect the colour coded plastic trim. Having done this, it was clear the failure was actually one of the two small black wires buried inside the handle. It had actually rotted through but this was not visible until the handle was off the car. So, wire repaired and the 4 fixings re-fashioned (brass inserts thrown over the hedge) and it is of course working fine. What an absolute headache caused by a tiny piece of wiring and rusted fixing bolts!