Hello all, first time poster, long time lurker.

I have an annoying issue with my 2011 Lexus RX 350. When driving and going over small bumps and at highway speeds my car will beep and show the "Back Door Open" error. As I continue driving, the light will turn off and on as I keep driving over small bumps. The power liftgate still works, as does the rear latch. When I am parked and the rear hatch is closed, I can push down and pull up on the hatch and the interior lights will come on, possibly signaling that while the latch does function, it might not be holding the rear hatch as tightly as the system would like. Is there a way that I can fix it myself, or will I have to take it in to get the latch replaced?

 

I would suggest to start with checking the rear latch for loose parts and apply some anti-seize. You should be able to get a better handle from inside the trunk area by removing the small cover. . The picture below illustrate how you can access that.
I hope this will end it but if the problem persists, then the latch mechanism assembly might be the next to blame. Keep us posted please.
Thanks,

 

Hi heshamos,

Thank you for your reply and for the diagram. I popped the cover off and it seems that the mechanism is loose and "jiggly". I added some moly grease and silicone spray. It seems to have improved the issue, as the "back door open" error only came up once on my way to work. I plan to take it into the shop to get the latch adjusted. Hopefully there is a way to tighten the mechanism without having to get a new one.

I will keep this thread posted.

 

A simple job for any body shop.

 

I'm glad that things are "loose" and I hope it's a matter of tightening a few bolts.
Last time I heard of a similar issue, it was a damaged ECU for the rear gate.
All the best!

 

Reviving an old post, but since I found a good DIY solution here thought I'd post (hint.. it's not the ECU!).

I have been dealing with this issue on and off for the last 2 years. This weekend it got so bad it would beep and go off every 30 seconds while driving, making the car basically undriveable. Decided I had to dig in to fix this once and for all.

Here's the breakdown of what I did:

1. Remove the interior paneling around the rear liftgate. (See here for some tips)
2. Tried unplugging the pressure sensors in the side weatherstripping (parts 82460G and F). Don't need to unbolt them, just unplugged a two pin black connector near each side, near bottom of the liftgate. Problem still occurred. Sensors probably not the problem.
3. Tried bypassing the pressure sensors with a 1kOhm resistor (I measured the resistance of the pressure sensors), still no luck. Still same problem. Sensors definitely not the problem.
4. Tried unplugging the switch to open the rear liftgate. Thought maybe an intermittent connection. But no, still same problem. Switch is not the problem.
5. Lastly, I noticed a white multi-pin harness that was just bolted to the door, not connected to anything else. All black and white wires in it. I assume this was the ground reference for all the sensors. I unbolted the 10mm screw and found that the surface was painted underneath. Assumed the harness had a bad ground connection, so I took some sandpaper to strip the paint down to the metal around the bolt, then put the harness back on. Plugged back in all the other sensors and switches. Test drove, problem solved!

Result: Bad grounding design. Lexus flaw. Must have worked fine with a new screw, but after years of the screw oxidizing started losing its connection.

 

Well done....

 

5. Lastly, I noticed a white multi-pin harness that was just bolted to the door, not connected to anything else. All black and white wires in it. I assume this was the ground reference for all the sensors. I unbolted the 10mm screw and found that the surface was painted underneath. Assumed the harness had a bad ground connection, so I took some sandpaper to strip the paint down to the metal around the bolt, then put the harness back on. Plugged back in all the other sensors and switches. Test drove, problem solved!

I just wanted to express a sincere THANK YOU! I took the system apart this morning and everything seemed perfect. While I was researching options, I ran across this post. And sure enough, the paint underneath the connector is perfect. Stripped it and sanded everything, it now works like a charm. Thanks again!

 

Does anyone have a picture of where the harness is. I am having the same problem, but I do not see the harness.

 

It's the white one, driver's side.