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

[Nick2020]

Can anyone help or advise me on a fault that’s developed with the Power Back Door (PBD) on my Lexus RX450h 2010 model.

A brief background behind the issue……..The car had not been used for over a month, and the auxiliary 12V Battery in the luggage compartment had become flat. I discovered this when I went to open the Power Back Door (PBD), using the remote fob (holding the boot release button for 2.5 secs), it made the usual audible sound but failed to open due to the low Battery condition.

I disconnected the auxiliary 12V Battery and fully charged it, but now the PBD fails to open either via the PBD open / close switch on the dashboard, the external switch on the tailgate or the remote fob. 

I have carried out some troubleshooting and steps to try and resolve the fault without much success, this included:

1.     Checked to make that the main switch to activate the PBD, which is located in the glovebox, is still set to the ON position.
2.    Tried performed the initialisation steps detailed in the owners manual (page 90) several times.
3.    Disconnected the 12v auxiliary Battery for over 30 mins, then tried reconnecting it and performing step 2.
4.    After initialising the system several times I have tried to open using  either the switch on the dashboard, the external switch on the tailgate or using the remote fob.

What I have observed when I try to open the Power Back Door is:

1.    There is no audible sound (2 beeps) or indicator flashes when the open/close button is pressed on either the dashboard, the external switch on the tailgate lid or the remote fob.
2.    I can’t manually open the tailgate.
3.    I’m only able to manually release the back door by removing the small rectangular cover inside the car, then opening it by using the release lever. 
4.    When the back door is manually opened the 3 x cargo lights in the luggage area do not light up (all the other car interior lights work fine).  I have checked the 3 x bulbs, which are all okay and made sure the switch on each light is set in correct ON position.
5.    The external buttons on the back door above the number plate, when pressed, open and lock all the other doors on the car, so I'm guessing it could be an issue with PBD lock only. 
6.    The reversing camera on the tailgate works fine too.

The owners manual mentions a fuse in the engine compartment (Type B fuse box - Fuse 9   30A - Power back door system) (see pics), but I can’t see any way to easily remove or check the fuse?

Does anyone know where the switch that activates the 3 x  cargo lights is located (PBD Lock, lift motor or another location)?

Are there any other fuses, relays or other points on the car  I should check?

Does anyone have detailed information about the operation of the PBD lock and lift motor or a circuit diagram? 

Any helpful advice or other areas you can suggest to check would be appreciated, as I’m now running out of ideas.

Thanks

[Jho]

Hi it’s desame problem of my car 450h

they charge me £95 for diagnosing the car 

£950 for parts and labour that the Lexus garage will charge you if bring your car with them so my opinion is bring it on local garage first to be honest over charges Lexus car company.

[kenc]

Speaking of the Power On switch in the glove compartment, I didn't know there was such a switch. So, when the rear power door stopped working last Friday, I telephoned Lexus (I won't reveal which one) to tell them that I can manually open and close the rear door but if I press any of the buttons I just get two short beeps and it won't open. I explained this in detail to the person on the service desk and it was agreed that I would bring the car in for a full investigation. On reading Nick2020's post above, I saw the reference to the switch in the glove box so just went out to have a look. Sure enough, it was in the 'off' position. Its location, right at the front of the glove box, means it can easily be knocked from 'on' to 'off' which seems to have happened to me when putting something into the glove box, last Friday.

My mistake. I agree. But, I would have expected the service desk's first question to me when I telephoned them to have been something like "You haven't accidentally switched the button in the glove box, by any chance?" But, no, I wasn't asked despite explaining the issue very clearly. Even now when I rang to cancel my visit to have the "problem" fixed, the chap on the service desk didn't seem to know that there was such a switch to turn on or off the rear power door.

Hmmmm!!!

Thanks Nick. You've saved me a journey and possible expense.

[royoftherovers]

Ken, if you had read your Handbook then you would have solved your own problem before Nick had even posted ?

[kenc]

Who has the time to read through a handbook of that size?

[royoftherovers]

Just now, kenc said:

Who has the time to read through a handbook of that size?

I did Ken.

If I am investing a considerable sum in my Lexus I am obliged to not spoil the ship for a halfpenny of Tar  (if you follow me )

And whilst I was reading it I noticed that it was longer than the document issued by the Scottish Government when it tried to pursuade the Scottish people to leave the UK !

[Herbie]

Surely, as the owners of these cars, isn't it our responsibility to read the owner's manual when we first take ownership?

Even if the dealer doesn't supply a paper manual, in these days of the Internet a quick visit to the manufacturers website would usually get a result or if not, a quick Google would.

[Herbie]

10 minutes ago, kenc said:

Who has the time to read through a handbook of that size?

Me. Cover to cover (skipping obvious bits that we all know).

[Nick2020]

Hi Ken,

I’m glad to hear the switch in the glovebox fixed your problem, I just wish the fault on mine was as simple to resolve.

If I get chance at the weekend I’m going to remove the PBD lock assembly, then get the multimeter out to  check the motor and switches.  I’m thinking that the sequence of operation is that the lock opens first, then the lift motor operates to open the back door.

Perhaps the motor / switch has failed or the gearing is out or alignment?

[Herbie]

@Nick2020 I've just sent you a PM that may be of use in solving the problem.

[granadaman]

Having same problem as nick if you can send any help my way also it would be appreciated 

[Herbie]

58 minutes ago, granadaman said:

Having same problem as nick if you can send any help my way also it would be appreciated 

Just sent you the same message Mick.

[Nick2020]

Hi Herbs,

Thanks for the information...this is very detailed and I’m sure it will be extremely useful in helping to diagnose the fault 😀

[granadaman]

Thanks herbie it will be a great help if I find a solution I will post back on here.

[Herbie]

You're both very welcome

[Nick2020]

Hi Mick, let me know how you get on and I will do the same. I’m hoping to get out to car this weekend to check the lifter motor and ecu, as this seems to control pbd lock mechanism and luggage lights

[granadaman]

going to have a look on sunday will keep posted

 

[Nick2020]

I’m pleased to report that the fault on the power back door has now been resolved, although I’m still none the wiser as to what caused this failure.

I had previously tried disconnecting the power back door lock connecter, then checking the mechanism and switches, but no problems were found.

This weekend I took the car on a 20 mile drive to charge up the hybrid and auxiliary batteries, which I had not done since the auxiliary Battery had been previously charged.  I stopped the car and put it in park, with the ignition still switched on, then tried operating the boot release switch on the dashboard. To my surprise there were two beeps and the power back door opened, so I then closed the power back door using the switch on the tailgate. Next, I tried opening and closing the back door using both the remote and switch above the number plate, which I’m pleased to report are all working now.

All I can really put this down to is either a glitch in the ecu, bad connection which cleare whilst driving or the hybrid Battery condition low.

[paul rozelaar]

On 1/28/2020 at 5:30 PM, kenc said:

Speaking of the Power On switch in the glove compartment, I didn't know there was such a switch. So, when the rear power door stopped working last Friday, I telephoned Lexus (I won't reveal which one) to tell them that I can manually open and close the rear door but if I press any of the buttons I just get two short beeps and it won't open. I explained this in detail to the person on the service desk and it was agreed that I would bring the car in for a full investigation. On reading Nick2020's post above, I saw the reference to the switch in the glove box so just went out to have a look. Sure enough, it was in the 'off' position. Its location, right at the front of the glove box, means it can easily be knocked from 'on' to 'off' which seems to have happened to me when putting something into the glove box, last Friday.

My mistake. I agree. But, I would have expected the service desk's first question to me when I telephoned them to have been something like "You haven't accidentally switched the button in the glove box, by any chance?" But, no, I wasn't asked despite explaining the issue very clearly. Even now when I rang to cancel my visit to have the "problem" fixed, the chap on the service desk didn't seem to know that there was such a switch to turn on or off the rear power door.

Hmmmm!!!

Thanks Nick. You've saved me a journey and possible expense.

Ditto Nick. Thank you from me too. Problem solved! Paul

[paul rozelaar]

Ditto Nick. Thank you from me too. Problem solved! Paul

[F1valk]

I have the same problem. Left the kids at school the other day and same afternoon it suddenly stopped working without any reason (no accident/maintenance or adjustment to anything on the car).

Granadaman, jho and if anyone else have the same problem, have you solved is?

I am charging the Battery now and will drive a longer distance some day soon but I assume it won't solve it. I have run out of batteries several times but never had this problem before. 
 

If I come to a solution I will post it here.

[ColinBarber]

Perform initialization of the power back door system (power back door ECU initialization) if one of the following is performed:

1. The cable is disconnected from the negative (-) auxiliary Battery terminal. Or the Battery goes flat.

2. A wire harness of the power back door system is disconnected and reconnected.

3. The power back door ECU (back door motor unit) is replaced or removed and reinstalled.

4. The ECU-B fuse is replaced or removed and reinstalled.

If initialization is not performed, the power back door system will not operate.

1. When the back door is open and the cable is disconnected and reconnected to the negative (-) auxiliary Battery terminal, fully close the back door by hand to initialize the power back door system.

   Tech Tips

   • Initialization is not necessary if the cable is disconnected and reconnected to the negative (-) auxiliary Battery terminal while the back door is closed.

   • The power back door ECU controls the locked or unlocked state of the back door based on its memory. If the power for the power back door ECU is disconnected and reconnected, the back door will need to be unlocked before it can be operated.

   • If the power back door system does not operate and/or the back door does not open, disconnect the cable from the negative (-) auxiliary Battery terminal. Then wait 10 seconds, reconnect the cable and perform initialization of the power back door system again.

[Hedley John Mayze]

I have just posted same problem on my 2012 450h. You may now find you have my problem. The lid of the fuse box you photo’d shows a green 30 A fuse for pbd (power back door) so I was expecting to be able to replace the blown one. However it seems to have been changed to a fusible link as pictured in your photo (same colour).I have never come across these before  I took out a 10 ml nut but didn’t help. If anyone replies to me I’ll let you know.

[GSLV6]

I have the same problem.  Let my auxiliary Battery go flat over the last 2 weeks (I know I ought to have hooked it up to my charger).  I connected the Battery (insitu) up to my CYTEK "intelligent"  charger after Lexus confirmed it didn't need to be removed to recharge the Battery (it won't damage electronics doing this).  No rear courtesy lights work, reset as per manual doesn't work, disconnecting Battery -ve terminal to reset the ECU didn't work, toggling the glove compartment button doesn't work.  It used to operate a relay in the fuse box, but I hear no relay operating and if I am lucky it is just a blown relay which could have occurred when I attempted to open the tailgate one morning it was freezing (causes overcurrent which could trip the relay or burn it out).  I have the later buzz-bar high amp common connector for power feed in the fusebox, covered with the green plastic top which I cannot see how to remove.  Called Lexus and they say I've done everything that they would have tried but they have offered a 30 minute free diagnostic session tomorrow.  My warranty ran out in July and as we couldn't use the car anyway (we were using a smaller runabout for shopping etc during lock down and self isolation) I didn't renew it foolishly.  I suspect it's one of two things: either 1) a blown relay as nothing in the rear is getting power, or 2) the rear (separate) ECU which operates the rear lock and power door motor/sensors.  It might even be a faulty rear sensor which I guess is a micro-switch buried under the rear panel somewhere.  Whatever, I am crossing my fingers it's nothing seriously expensive!  I despair with Lexus.  Every time I've had a flat Battery on any of my lexus cars, something like this ALWAYS happens!  The only car that has been faultless is our 16 year old 105,000 miles Toyota Rav4 which is just indestructible and utterly reliable.  If this is a big bill, I will have to seriously consider keeping the car.  I am now relying on it for longer runs to hospital as my wife is a cancer patient (as of November) and we have to depend on the RX.

[Kate2140]

Hi @Herbie would you be willing to send me the details you sent to the others? We are having the same problem but intermittent (most often doesn’t work), tried charging the aux Battery, but that’s not helped

thanks in advance !