Power Back Door (Tailgate) not working on 2010 (Series 3) RX450h

TheoRX · February 28

On 2/22/2024 at 8:17 AM, karumesilane said:So my conclusion is that cold temperatures are the cause in my case. But now is the question - where is that weak point that gets affected by cold weather?

Interesting, Did you check your auxilliary battery's output? I wonder if a low output from this might affect the PBD motor activation when it drops below a certain level, because it seems your ECU/motor unit is working OK, just doesnt like the cold/or get enough power to operate in the cold.. Whats tricky about Lexus hybrids is you dont get the tell tale lazy starting to indicate low battery (as the starting is off the traction battery -I believe). I think as my PBD - ECU started to fail it caused a battery drain which meant i was forever trickle charging it through winter. Its a real game of spot the red herring.

DudeWheresMyBackDoor · March 26

I also have this problem with my 2012 RX450h. It has sat outside in very cold nordic temps this winter, and I only use it maybe once a week or less, due to working remotely nowadays. The back door used to work from button inside and the key fob until I noticed yesterday (after a loooong time not using the back door) that no matter what I do I can not get the back door to open. Manual button above the license plate does nothing, not one bit of sound. Lock button there works. I would like to get your information also @Herbie if that's not too much trouble. Really looking forward to not having to cough up something north of 1500 euros to the local Lexus shop. I used to take my old RX400h there, and it's somehow always cost an arm and a leg. I figured it's cheaper to get a newer Lexus and it doesn't look like I'm doing it right, lol.

*edit. While waiting for the secret information, I'll get the multimeter out to rule out the Battery voltage... I've seen some low batteries in a lot of cars, and from how well this thing operates, I'm assuming the Battery will be fine.

David450 · March 26

I have a similar issue with a 2011 RX450h. The tailgate has often stopped working in the past when it is raining heavily, but has always come back when dry. Recently however it has refused to open; wet or dry. I can open by lying down in the boot area and using the manual lever, but this is impractical when carrying anything in the boot. Any ideas?

Herbie: any chance of the info DM?

David450 · March 31

It has started working again! Dry weather and it's fine. The only thing I did was to press the on/off switch on and off a lot of times.

Does Lexus have a fix for this issue? Seems like lot's of people have the same problem.

Chassis · March 31

Thank you all for an interesting thread!! The RX is such a rock solid car... obviously apart from the PBD... I have the same problem as many of you seems to have. The PBD won't open, or close or react in any other way regardless of method. I can lock/unlock all four doors from the tailgate handle but not operate the gate itself. I have disassembled enough, including opened up the head liner from behind to see the lift motor and from that, it looks like a limited project to replace it, if necessary. Can the old motor assembly somehow be saved? By resolder the PCB? Or by replace some component that commonly fails? Capacitors, for instance can be weak apoints in some designs. Guess that electronics are more prune to fail than the mechanic parts and both the lift motor and latch motor are affected

And Herbie, if you still are in this thread, would you please send me your fix?

Human · May 4

@Herbie can you please send me the same information you send Nick and others please ? thank you!

DudeWheresMyBackDoor · May 8

Well since this Herbie fix doesn't seem to be a thing any longer, I did the other thing, which is I took it to the local shop and paid surprisingly only 1100 euros for a new control box and the repair work.

It works now, so everything turned out all right in the end.

GSLV6 · May 8

I had this on my 2014 RX. It affects more cars fitted with roof rails than not, a clue perhaps to the cause? Mine was diagnostic checked after I tried all the usual fixes, including Herbie's fix. I got it working for a few days and it packed up for good. In the end, the roof lining had to come off and the problem was discovered. Moisture seeps through, it seems, from the roof rail fixings (where fitted) and eventually builds up in the power control board, shorting it out. If only a little builds up, the tailgate will often start working again for a while but left in this state with moisture getting through, it will eventually fail. It's a design or manufacturing defect as far as i'm aware and ought really to be fixed under warranty. I had mine done after warranty when presenting Lexus with a reasoned argument so had to pay nothing to have the motor board replaced. Apparently the motor has burned out too although the odd thing is that it worked intermittently prior to replacement. That. too was replaced under warranty.