I've searched this forum, not finding anything about pinch sensors. Thought I'd ask here...

From all the google results, it sounds like the issue is either one of the pinch sensors, or the power struts that open the hatch. Both look like very simple DIY repairs, the question is: How do I determine which parts need to be replaced? I brought it to the local toyota dealer, they told me it was working as expected (which means they didn't even bother trying to hit the button to open the hatch), and then to a local mechanic who said they weren't getting any codes on the computer - but my guess is this is very lexus specific, and a generic computer won't show the pbd sensors.

Has anyone figured out how to tell which parts are not working correctly? I'm sure that I could take it to a lexus dealer, but I'm concerned they'll just swap out all the parts, which, tbh, will be very expensive.

BTW, I live in the Boston area, in case someone has a recommendation for a reputable mechanic who can diagnose it correctly.

thanks for any help here!

 

Believed that Car Care Nut has a vid on YT where he did a power strut changeout on a Rav4. Very similar platform to the NX. You may get some insights/ideas from this vid.

 

You describe the symptom as "not opening". Can you physically lift and open the hatch?
Does it stay up if lifted up? If it fails to stay open, then it would seem to be the struts.
The hatch (rear door in Lexus-speak) is treated as a door, not a trunk lid, by the door locks.
If all the doors are locked, the power lift won't open it. Try with all the doors unlocked, not
just the driver's door.

 

Hi, thanks for the tips to diagnose, I'll answer each one here:

1) I can physically lift the hatch and close it, although it's very heavy.
2) The hatch stays up once I lift it, which is one of the reasons I think this is a pinch sensor.
3) When I hit the button to open the hatch(on the fob, on the hatch, or on the dash), it unlock, moves up a tiny bit and then beeps a couple times and stops. Each time I hit a button after that, it moves a tiny bit, and then beeps a couple times and then stops.
4) Pretty sure it's not a locking issue, since I hear it unlock and it moves up a bit. When I push down, it automatically pulls the hatch closed and locks it.

Definitely appreciate any futher thoughts!

 

The height of the open back door is adjustable. Open the hatch either all the way
or to a height that suits you. Press and Hold the edge mounted hatch close button.
You will hear a couple of chirps that it has registered that position.
Now try the various hatch closing and opening buttons. If it somehow had memorized
the nearly closed position as your choice of open... it won't open.

 

Hi, I tried this, unfortunately, it didn't help. It doesn't matter what height I set it to, it still won't open beyond a few inches when it's closed. If I have the hatch raised, it won't go down when I push any of the buttons either, just moves a tiny bit and then beeps. That's why I think it's one of the pinch sensors, but I haven't been able to figure out which pinch sensor.

Thanks for sharing this possibility.

 

Have you tried the following ?
1. go to the MID screen "settings display"
- set the door manually in desired position.
- press & hold power back door switch for 2 secs. buzzer will sound 4 times.
- try closing door with button/fob.

Or if no joy, then try this.

2. To return back door to initial settings.
- press and hold PBDS for 7 secs.
- buzzer will sound 4 times and then twice more.When power back door is operated the next time, door will open to initial settings position.
These steps from Owners Manual ( 2016 NX200t )
FYI, @mcomer mentioned that you may have mistakingly memorised the "new" opening sequence with repeatly pressing button. That is a real possibility.

3. I'm throwing this step out as a last resort.
- disconnect NEG clamp on battery for 10 mins. hopefully it 'll clear settings and revert back to factory specs upon reconnecting NEG terminal. Caution: other settings ( radio stations ) may be lost with this step, IDK. All other pertinent settings may revert to factory as well.

 

If you press button and lift at the same time does it open more?

 

I tried 1 and 2 above, neither worked. I'm hesitant to try #3 since that will probably reset everything in the car. (I had tried these before, but, figured it couldn't hurt to try again) Opening/closing the hatch didn't change no matter how long I held the button on the hatch. I'm guessing I'll need to take it to a dealer to get it diagnosed at this point. I very much appreciate that you shared the above ideas!

 

Pressing the button while I pulled up on the hatch didn't make it any easier to open the hatch. It just beeps twice and stops. I can lift the back hatch manually, but, it's very heavy and continues to beep as I move it. Thanks for the idea!

 

There is an easy way to determine if the pinch sensor switch strips are functioning correctly; and a hard way.

The easy way is to connect an interface cable and computer running Toyota Techstream software to the OBD2 port. This software can monitor the pinch sensor switch voltages while someone presses each one. This might take all of 15 minutes of a competent dealer technician's time. Refer to the attached diagnostic info.

The hard way is to remove all of the liftgate interior trim panels to access the rear door ECU (item 8 in the attached component location drawing). Un-plug connector "Y26" and measure resistance between the terminals shown in the table (6 and 24; 26 and 24). With the indicated sensor strip pressed, resistance should be low (~less than 10 Ohms). When not pressed, the resistance should be higher, but not infinity. There are resistors connected in parallel with the sensors, which permits the ECU to differentiate between an "un-pressed" and completely disconnected sensor.

Not sure about greater Boston, but down here in the great state of corruption, the sole Lexus dealer responds to all technical complaints by selecting a reply from one of 2 books: the book of excuses and the book of "non-answers". I bring my NX to a Toyota dealer for all service needs. The 2018 NV and 2018 Rav4 are the identical chassis, and the same Techstream software is used by Toyota and Lexus technicians. When visiting a Toyota dealer with a service question, I always bring a box of Dunkin' Donuts, which is a preferred form of currency in most New England states .

 

@n0v8or - thanks so much for the advice!

I took the back hatch panels off, and removed the pinch sensors so I could measure the resistance across the pins in the cable from the pinch sensor, not the Y26 connector. When I measure them, (both are about the same), they are at 0.983 ohms if I'm not pressing on the pinch area, and anywhere from 15 - 50 ohms depending on where I pinch them. I checked again after reinstalling the pinch sensors, and they were both at 0.983 as well. I expected just the opposite of this behavior, since I'm guessing the wires in the pinch area are probably closer when pinched and therefore have less resistance. I think it's unlikely that they both failed at the same time, but I guess it's possible.

I guess next step is to figure out if the issue is the power struts. Any suggestions for that?

Again, thanks very much for the great advice above!

 

I must admit I am perplexed as to why your resistance measurement results appear to contradict the Lexus Technician training description (refer to attachment). I wonder what would happen if you temporarily disconnected both sensors and wedged ~33 ohm resistors into the ECU side of the sensor connectors.

 

Alternatively, you could open the hatch several inches manually, then use a bungee cord and 2 rolled up socks (or 2 brave helpers) to keep both sensors depressed while you try to open it further with the power opener switch.

 

I think I unintentionally led you astray with this comment in Post #11: "~less than 10 Ohms", which turned out to be inaccurate. Your 0.983 measurements are both stable and consistent between sensors. This tells me they represent the resistors connected in parallel with each sensor. not the sensor element resistance. If using an auto-range meter, 0.983 may have been actually indicating 0.983 kΩ (983 Ohms, or ~1kΩ). The 15 - 50 Ohm measurements therefore represent the depressed resistance. My conclusion: the sensors are both OK and resistances agree with the Lexus description.

Given the observed symptoms, a failed pinch sensor was a good first suspect, but is time to move on to the next. My choice wound be the motor inside one of the power struts is not operating. When only one operates, the entire hatch may tend to bind and the one strut trying to do the work of two trips its internal overcurrent protection. Here are 3 ways you could attempt to confirm (or refute) this theory:

(1) Open the hatch part way by hand, high enough so you can wrap your hand around each strut, one at a time, at a point closer to the roof, to see if you can feel the motor running while a helper operates the opener switch.

(2) Operate the opener switch numerous times in succession until the hatch has been moved from closed to nearly open. Now immediately feel each strut to see if one is noticeably warmer than the other.

(3) Stand behind the vehicle while a helper operates the opener switch multiple times. Look for one side to consistently rise more readily than the other each time the hatch moves a small amount, then stops.