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

ColinBarber · September 9, 2022

That is interesting - the system is shutting itself down because of a sensor fault

debs01 · December 2, 2022

Hi I am having the same problem with my boot and have tried all the obvious solutions and nothing works. @herbie if you could send me your information I would be very grateful, thank you

Herbie · December 2, 2022

1 hour ago, debs01 said:

Hi I am having the same problem with my boot and have tried all the obvious solutions and nothing works. @herbie if you could send me your information I would be very grateful, thank you

Just sent a PM to you Deborah.

Grey RX · December 16, 2022

After reading through this thread a few weeks ago I have now experienced failure of the power back door this morning. I'm hoping it is related to the minus 7 temperature but would appreciate any advice on the problem please. Won't open but seems to manage to close partially (enough to hit my head) according to my very quick look before my wife went to work.

Thanks

Richard

GSLV6 · December 24, 2022

Just had the same thing happen on a 2014 RX3. Charging the auxiliary Battery normally sorts it but this time it didn't so also open to suggestions as it's a right pain clambering about over the back seats every time I need to open the tailgate!

RX450HPrem · January 5, 2023

Hi, after having a bit of a leaky RX300 rain ingress and now own a 2010 RX450H and experiencing the fatal rear boot motor issue on my premier Model, Checked 30 amp fuse in engine (bus bar) if you have a light and a magnifying glass you can just see the soldered Joint for the fuse, all good. couldn't find relay for PBD ? but did start taking boot and rear roof apart,

I have spent most of the day reading the forums for info (interesting) but no real solution apart from expensive costs and several potential causing issues. My Aux Battery is new and was installed about a year ago so all good. I did notice however when looking at the motor in the rear roof of the car drops of water were seen, water on inside of roof also sointhe process of drying to see if it recovers. However while looking at this issue has anyone reported if they have sun roof cars ? does the drain pipe run to the back on the RX450H ? or rear door seal causing issues, certainly looks like mine is a water ingress issue that has caused the motor to go. I'll keep investigating 🙂

steveledzep · January 5, 2023

Roof rail bolts.

RX450HPrem · January 6, 2023

is that a commonality ? are all cars being affected have roof rail bolts ? I will check mine out thanks.

RX450HPrem · January 6, 2023

Ok so after removing Rear boot motor found droplets of water inside of roof also slight water on Roof rail bottom bolts not much though, Small droplets on plastic cover for printed circuit board looks more like condensation but who knows, All electrics were dry just a few droplets on cover

I am getting 12v from the large yellow cable on plug and also 12v on thin brown wire on right hand side of plug - Does this mean I am getting power to the back for the motor ?

As stated before 30amp in engine bay is ok, not sure where relay is but assume working as power to rear motor ?

just trying everything before maybe getting a new unit 😞

Thanks

Paul

ColinBarber · January 6, 2023

55 minutes ago, RX450HPrem said:

As stated before 30amp in engine bay is ok, not sure where relay is but assume working as power to rear motor ?

There is no relay between the 30 A fuse and the motor assembly. The yellow wire is the main feed.

The relays that operate the motor are on the board - the white Taiko relays are the first things I'd be replacing although some people have reported the device stops being visible on the CAN bus which indicates a low voltage/signalling issue rather than motor control but there may be more that one failure point on these assemblies.

This is water evidence on this IC? Difficult to tell in the picture.

RX450HPrem · January 6, 2023

2 hours ago, ColinBarber said:

There is no relay between the 30 A fuse and the motor assembly. The yellow wire is the main feed.

The relays that operate the motor are on the board - the white Taiko relays are the first things I'd be replacing although some people have reported the device stops being visible on the CAN bus which indicates a low voltage/signalling issue rather than motor control but there may be more that one failure point on these assemblies.

This is water evidence on this IC? Difficult to tell in the picture.

Thanks Colin not being an electronics expert I think you'r saying that the board is broke - Does anyone know where you can just buy the board ? rather than the whole unit ? looks like im in shopping mode now 🙂

Thanks

Herbie · January 6, 2023

5 hours ago, RX450HPrem said:

Thanks Colin not being an electronics expert I think you'r saying that the board is broke

Can you clean up that chip to read what's on it? If we can find out what it is we may be able to get a replacement and then it's easy enough to swap it out.

RX450HPrem · January 7, 2023

Hi Herbie,

It seems there was a film of what I would call varnish or rubber solution on the chip and now I have cleaned it off looks fine but you can see chip details better. Hopefully the rubber solution (or what ever it is) that they put on in manufacture was making the chip look blown or an issue.

Have a look see what you guys think ?

Also I think you have messaged people with a work around - could you please let me have a copy, Thanks

Paul

ColinBarber · January 7, 2023

2 hours ago, RX450HPrem said:

Have a look see what you guys think ?

If it wasn't water then it will be fine.

18 hours ago, RX450HPrem said:

Does anyone know where you can just buy the board ?

It isn't available on its own unfortunately.

RX450HPrem · January 7, 2023

Thanks Colin

Seems really strange this issue, I know people maybe have a theory that it is affected by the aux Battery. We did have a really cold spell here so any Battery would lose a percentage of power due to low temps and snow on the roof for a few days maybe it leaked through and water damage has caused the issue.

I wonder if any failures in hot countries ?

And if a Lexus issue would be nice if you could buy just the board as its an easy replacement procedure.

I rang a parts dept at a dealer and in their words 'they thought the replacement cost was extortionate ! 🙂

Note My Aux Battery was good.

If anyone has imported one successfully please let me know

Thanks

Paul

ColinBarber · January 7, 2023

16 minutes ago, RX450HPrem said:

Seems really strange this issue, I know people maybe have a theory that it is affected by the aux battery.

I don't believe it has anything to do with the aux Battery. If the voltage is low then the power going through the assembly would be less so isn't going to overload it.

We get more reports of this issue during the winter months. It could be temp related, which could be an indication that the relays aren't switching correctly or a temperature related component failure, or is due to more rain in the winter and water is shorting out the circuitry. There are reports of it being an intermittent issue for some people, at least initially, which would also indicate a temperature/moisture issue.

It could be a problem with the motor itself, although unlikely. I don't think anyone has just swapped the board over, they just fit the complete replacement assembly.

RX450HPrem · January 7, 2023

Thanks Colin

I attend to agree with your comments not the Battery but moisture issue

Paul

NemesisUK · January 7, 2023

I don't think I'd be replacing anything until it has be diagnosed properly using Techstream

Herbie · January 7, 2023

6 hours ago, RX450HPrem said:

Hopefully the rubber solution (or what ever it is) that they put on in manufacture was making the chip look blown or an issue.

Yeah, that chip looks alright now that you've cleaned it up.

PM sent to you Paul.

GSLV6 · January 12, 2023

Mine's been into Lexus who spent hours pouring over the vehicle with test probes and laptops. They've narrowed the fault down to a Canbus wiring fault but don't know where. The signal which is being relayed to the rear ECU isn't triggering the motor for the rear door as the power feed is dead to the motor (fuses are all fine) but everything else works fine. They're getting no unusual fault codes which help them so are having the car in again for several days to remove rear panels on door and headlining, go through the wiring, find the fault and repair it. I've already indicated if it's an ECU replacement needed as the car is under warranty, I won't be stumping up for that nor any water damage caused by roof rail bolts as they fitted the roof rails!

Shornw · January 14, 2023

I have a similar issue but slightly more annoying. PBD was working fine before I went away for two weeks. When l returned the car (2010 Rx450h) wouldn't start. I had to manually open the rear door to get to charge the Battery and got the car going... The PBD wouldn't open after that. I made sure the glove box switch was set properly and checked everything I could find. I cleared down all error codes and bought and fitted a new Battery yesterday as it should hold enough charge for more than two weeks. After this the PBD opened and CLOSED no problem (According to Colin Barber's Post, removing the Battery and cuneiform a new one would have initialized the ECU) .... This morning however, nothing no beeps and the car does not recognise that the rear door is open when opened manually. I've always thought the powered back door to be a gimmicky lazy thing and this really does seem like a flaky and irritating system as the only way to get the door open is to clamber over the back seats to operate the manual unlock.

I will try disconnecting and re connecting the Negative terminal when it stops raining but is there something I'm missing? I guess it could be that the ECU started playing up as the Battery got flat not that seems very coincidental

Thanks for reaching and for any ideas anyone may have

Shornw · January 14, 2023

It stopped raining finally so I tried disconnecting the Negative, waited a full minute and reconnected it, shut the door manually then posted the car on - got the 'loading system, do not power off' message then tried to open the door with the the inside button, the remote button and the back door button. No sounds nothing except the external button locks the car.

Having read through the thread a couple of times I still don't feel any closer to understanding what the problem is. To summarise my thoughts..

1. It was working fine before the Battery ran low

2. It worked AFTER the faults were reset and a new Battery was fitted

3. The following morning it was completely non responsive

The above would indicate that the components are all working but there is some form of communication issue between the PCB ECU and the main ECU as the car doesn't recognise that the PBD is open (any other door being open is registered on the display and l can lock the car when it's wide open) - I know electricall issues can be seemingly random but some logic has to apply.... It may be coincidental but the front offside parking sensor also started playing up after the initial low Battery issue.

I haven't yet lookied at getting access to the ECU and motor but logic suggests if there was a component failure this would have occurred before the low Battery and also wouldn't have worked after the new Battery was fitted 🤷

It's both surprising and disappointing that, considering the number of instances of this issue, Lexus haven't identified the cause and a reliable resolution. In now not really sure how to progress. Do we know if anyone has taken this to a specialist motor electrical specialist?

Thanks for your patience and for any ideas

RX450HPrem · January 14, 2023

Rob, welcome to the logical way this fault seems to manifest ! 😞

Only thing I can suggest is try dropping the roof to see if you can see any damage to the Motor ECU, I.e Water ingress ? You said your car was laid up for a couple of weeks ? Was it in a wet environment ? they do seem to be very fragile to any sort of change. Humidity or Battery.

Update to all on my Issue.

Ordered a new part from UAE cost approx £600 and was shipped really quickly, arrived and fitted all working now ! Phew !! what a mess It seems like if you have a RX450H 2010 model, this is an issue you will come across some time or later.

I really cannot understand why these units seem to prone to a similar issues on the same car and same year and how we communicate this back to Lexus ?-

As for the detail I still don't know which actual item failed to cause this issue - as you need to change out the whole unit to fix when I suspect half of the mechanicals and motor are fine.

Thanks to all the people on here that helped in this and good advice was given to narrow down my fault.

Paul

Shornw · January 14, 2023

Hi Paul,

Glad to hear that you got it sorted even if it was at substantial expense.

The car was parked outside for the two weeks I was away but can't imagine that there was more chance of water ingress than over the last 13 years 🤷

If, as has been suggested, the issue is caused by water ingress, is there an opportunity to provide a higher degree of waterproofing? Maybe a coating or two of waterproof lacquer or spray on plastic coating or even shielding the vulnerable side from moisture with a waterproof deflector maybe?

Can l be really cheeky and ask what the part number you ordered from UAE was as it feels like I've spent recent days reading and re reading this thread and my eyes fell like they're about to bleed and my head explode not to mention my elevated depression levels, having only had the car since 24th December.... And I was away for two weeks after that 🙄

Once again, thanks to all for the work and effort put into this, and all other threads.

Herbie · January 14, 2023

10 minutes ago, Shornw said:

having only had the car since 24th December.

Was it from a private seller or a motor trader? If a trader then you may have legal recourse because I believe traders must offer a warranty, although I'm not sure if it would cover the PBD or not.