B12E8-23 (2F) Liftgate/tailgate control release switch - General signal failure - signal stays low.

I assume this is more likely to be a broken wire somewhere rather than a problem with the button.

Any suggestions on where to start looking? Or information on the wire colours, etc. to look for?

Thanks.

Any thoughts?

Does the tailgate not release then? I assume you mean the upper? Does the key release it?

The button on the top of the lower tailgate has suddenly started to misbehave. It does open sometimes, usually after a bit of jiggling around.

A non Range Rover owner here, but I stumbled upon this thread while looking for a cure for my Discovery 4 which was having the same issue. I seem to have solved it so here's what I know and done in case it helps.

I was getting codes B12E8-23 and B10C5-23, and the symptom was that the liftgate switch worked sporadically. When it didn't work, I had to lock the car, leave it locked for a minute or so, unlock it, and then it would work. Bizarrely, after being locked overnight, the boot wouldn't open at all in the morning before unlocking the car (locked release was not working). Clearing the above codes made them appear almost immediately, even if the lower tailgate/liftgate was not operated.

When the switch was disabled I could still open the liftgate by pressing the button on the keyfob but the lower tailgate button still didn't do anything (until the magical lock-wait-unlock trick). This made me think that some switch was 'stuck pressed' which triggered a system disable that disables both buttons.

According to the workshop manual for the discovery, code B10C5-23 is related to the "Upper tailgate exterior switch" and indicates a short to ground or 'internal failure'. Meanwhile, B12E8-23 is described as "Liftgate/Tailgate Control/Release Switch - Signal stuck low". Despite its description, the possible causes listed, both relate to the lower tailgate switch being stuck active, shorted, or grounded. There's a note that says this code will be set if the switch is active for more than 60 seconds too. There's no direct suggestion of a part replacement, it just says to test the lower tailgate switch and make sure it is not shorted/grounded. For B10C5-23 the manual says the liftgate switch might need replacing if the problem persists.

The fact all screws and bolts holding the liftgate switch contraption had rusted solid made unplugging things and testing impossible. I changed the liftgate switch (exterior) as I thought it was well likely to be the issue after 11 years in the elements. While I was at it, I also removed the rubber cap of the lower tailgate button to check it, and "massaged" the button to shift any trapped debris from under it.

All and all the issue seems fixed now! There are no more codes and the buttons work reliably again. I don't know which of the two steps above did it, nor how relevant this is to Range Rovers... I can't imagine the Disco is too dissimilar, so maybe it's worth a shot.

Hope this helps!