Last Sunday, getting to my 2010 RX450h after shopping, I felt a faint smell of burnt electric wirings outside the car, which however started normally, except that a caution message was showed in the main control panel, concerning one of the front doors opened. Furthermore the "door opened" alarm buzzer was on.
I double cheked all the doors, which were properly closed, but the caution message remained as well as the alarm buzzer. In short, I parked the car at home and did the following checks:
- even with the engine shutted down, the red warning light "door opened" was on in the control panel
- the remote works no longer to close the car (which is normal if one of the doors is sensed open)
- the mechanical key closes all the doors (it means that the doors lock are still OK)
- with the car closed, the remote works opening the doors; the same with the smart entry; this should mean that the related ECUs are still OK
- my Scangauge does not report any error code.
I disconnected the 12V battery in order to avoid its depletion, and two days ago brought my RX to the dealer... I called them today, apparently they are still groping in the dark ("we are checking the wirings").. Any hints?

 

Rodents eating the wire harness, maybe even nesting in the vehicle.

 

Hope that isn't the case. Bought a used LS 430 where the previous owner lived in an affluent neighborhood but was overrun with rodents. Rats gnawed through enough wiring that it required a $6000-7000 repair bill to replace the engine wiring harness. The experience taught us that a low-mileage car that isn't driven enough is not necessarily a good sign. Thankfully, the seller was a woman of great integrity and she still paid the bill after the sale. Just hope it truly isn't rodents and a wiring harness in the OP's case.

 

Hopefully the dealer will find a frayed or loose wire that has shorted out & burned. If so, that ought to be an easy fix, but labor costs will likely be high. This stuff isn't always easy to find.

A buddy's new Chevy Blazer got hit by lightning. Two months and $15,000 later, he got it back and it ran OK. Insurance covered the cost--luckily.

 

True, lately I havent used much the Lexus, wich moreover sleeps outdoors, so the "hungry rodent scenario" has some sense... however (correct me if I am wrong) unlike those under the hood the wirings related to the doors should be unaccessible by pests.
I suspect more a short in some hidden ECU, this car has a myriad of ECUs scattered thoughout the body.

It may be worthwile to note that when I left the car to the dealer I've got a quote for the diagnosis, 90 Euros. But there is no doubt that the labour hours charged for the repair will be proportional to the time spend by the dealer for the troubleshooting

Another nuisance is that I cannot take the opportuniy to combine whith this unscheduled inspection the periodic maintenance check which is due by May, because having disconnected the 12V battery my RX450h is not eligible for the Hybrid battery check, which here in Italy until the tenth yar of life of the car, may extend of 15000 km /12 months the Lexus warranty on the traction battery.... I have to drive at least 500 km before doing the hybrid check, because disconnecting the 12 V battery possible error codes stored in the ECU are lost..

 

Afer a week, I do not have my RX back yet. This morning I have spoked to the dealer, I've been told that the technician followed the harnesses path starting from the right front door, through the liftback, and has still to get to the left door and then finally to the ECU under the dashboard. Should I had to choose, I would have started the troubleshooting from the ECU... I know already that this one is going to cost me a fortune

 

Personally, I agree with the way the dealer is doing it.It can be a problem at the ECU end, but the best place to start is where there is evidence.

Salim

 

Today I've finally obtained by the dealer the diagnosys and the repair estimate. Apparently, the body ECU overheated, and partially melted the adjacent fuse box, shortening some contacts related to the doors.
The reason for the overheating, happened while the car was sitting in the parking lot, is unknown, and this worries me a lot.. The repair estimate is around 2800 Euros, which I accepted a bit thight-lipped, but I also asked them to investigate the reason of the overheat, and the intervention of a Lexus inspector to review this issue.
My reasoning is that if the body ECU was powered up with the car resting, and the overheating was not caused by another car component misbehaviour, then the body ECU has some design fault and this element should be considered carefully by Lexus, because my car could easily have caught fire.
I am not optimistic about a Lexus willing to share with me the repair costs, but as a minimum I want to be sure that the issue in subject will not happen again.

 

Final verdict: the root cause of the fault was an overload originated by the Meteo tail lights which I installed a couple of years ago. They showed to me the ECU contact board burned in correspondance to the tail lights wirings connector. This ECU is located under the driver knees, together with the damaged fuse box.

Luckily I kept aside the OEM tail lights, since Lexus graciously will put them back in position without additional charges. By other hands, comprehensibly they will not issue any warrant on the repair, unless Meteo tail lights are removed.

A (very expensive) lesson learned: never ever install non OEM parts on a Lexus!

 

That sucks, but yes always assume aftermarket lighting/electronics are of ****ty quality. There are very few exceptions, I would be looking to Meteo to provide some sort of remedy but since it's been a couple of years and likely out of any warranty if they even offer one. Pretty sure if you go public with this information no one would buy those lights anymore. So at-least they should have some incentive to make things right for you.