Rear Keyless Entry Sensors

[Boourns]

Just to add another data point: I have a manual hatch and I can open it if I approach from the rear without unlocking the car. I don't have auto-present door handles, though, since I don't have the tech package. Not sure if that would make a difference. When I open the rear hatch the door handles extend and all doors unlock (door unlock mode set to "All").

 

[SDRick]

I am only getting about a 20 or 30% success rate opening the trunk without unlocking first. Most likely a problem with the trunk key fob sensor.

Just to confirm, for those were this feature is working (and door handles set to open at once), do the door handles remain closed when you open the trunk manually with the button underneath the hatch?

 

[mikec8]

Mine usually has a little delay after pressing the latch button, then unlocks and opens up. Though in the early days I had the car alarm set to on and somehow triggered the alarm when approaching the car from the back and trying to open the trunk. Since then I turned the alarm off.

 

[iffatall]

Yeah it takes a little more than a second to open after I press the switch if the car is still locked.

 

[f-stop]

Just to confirm, for those were this feature is working (and door handles set to open at once), do the door handles remain closed when you open the trunk manually with the button underneath the hatch?

In summary:
With power liftgate, approaching from rear with fob in pocket, then pulling up the external manual trunk latch button
- if Door Unlock Mode = All, trunk opens and ALL door handles pop out
- if Door Unlock Mode = Driver, trunk opens but NO door handles pop out

 

[SDRick]

f-stop, mine works as you state above but only about 20 to 30% of the time. I have found that when my key is not detected, it requires placing the key about where the glass meets the bottom of the hatch before it is detected.

I am not aware of doing anything differently when it works properly. It is probably a defect with the sensor or something is blocking the signal.

 

[SDRick]

I thought I was clear.

There is a sensor at the rear which, if it detects a key, will allow you to hit the manual trunk latch on the vehicle allowing you to open the hatch.

The service center is telling me that there is no rear key fob sensor in the MS. I thought I saw a diagram showing a sensor back there. Any proof if there is a sensor back there or not?

 

[f-stop]

The service center is telling me that there is no rear key fob sensor in the MS. I thought I saw a diagram showing a sensor back there. Any proof if there is a sensor back there or not?

there's gotta be a rear sensor.

for example, my single car garage has a side entry door near the front left wheel of the car. Sometimes if I just want to grab something from the car, I unlock/open that side garage door but leave my keys (w/ Tesla fob) dangling in the doorknob. The driver door auto unlocks before I open the garage door. If I then walk to the rear of the car with keys still in the door and pull up on the manual trunk latch it won't open - it's still locked. I have go back to get my keys first to double click the fob to open the trunk. Or I have to take the fob with me when I approach the trunk and it will open. How would it work this way if there were no rear fob sensor?

 

[tennis]

A quick press of the button (from the trunk, not from the key) never works for me when all the doors are locked when I approach the car from the rear -- I have to hold the button for a second or two.

If approaching the car if the door handles happen to auto present when I go to the trunk, I quickly push the button to open the trunk and it opens, no holding down of the button required.

 

[CuriousG]

My problem is that my trunk remains locked even after I am right up against it. As was also mentioned by another up thread, I also need to walk around to the doors in order for the trunk button to unlock so it can be used manually. So is there a setting I am missing or is it something that needs to be addressed by service?

I've sometimes run into the problem where it doesn't open the first time and I hit the hatch button again and it opens up. Don't think it's taken more than two times though.

 

[SDRick]

For me, it either works on one & of the hatch button or does not work at all. I still have not been able to figure out why sometimes it works and others that does not. I have read that there is an antenna for the key fob back there. Perhaps it is defective

 

[Akikiki]

SDRick and Julesp313, I agree with what GaryREM has been writing. There is a fob antenna behind the bumper and tie wrapped to the outer frame area just about center of the trunk lid's release button. There's a chance that during installation, it didn't get plugged in to the connector it needed. I'd ask at the SC for them to check it next time. (I saw where/how the fob antenna is installed while watching a guy on youtube DIY a Torklift trailer hitch on his own Model S. Part of this required the bumper to be removed and we could see the fob antenna.

I added a fob antenna inside the trunk at the charging port door to allow my to unlock the UMC without performing the Tesla-two-step toward the front door before it would unlock/release. There's a write up of how to do it on Teslatap.com

But easier is trying the fob battery. Could be your fob battery is getting weak. Its cheap, you might try swapping out the fob battery to see if that fixes it.

 

[SDRick]

Ak:

I am with you on your post and did try a new battery. The car is only one month old and the fob battery was just a bit over 3 volts. The charge port upgrade is a great idea. How long did the install take and how much did the antenna cost?

 

[Akikiki]

SDRick, The fob antenna was about $ 25.00 Installation took about 30-45 minutes. I played around with where to run my wire, up the headliner or down and along the door sills. Settled on door sill areas. Once you get past the rear door sill, you must tuck the wire along the trim and behind the upper seat belt anchor point and around the parcel shelf plastic bracket. I know someone else on TMC that did it too. We both recommend you use shield 1 pair cable. The front door fob antenna is at the end of the dash (on both sides) attached to the sort-of-triangular trim at the end of the dash. (The door panels covers this trim when the door is closed.) You simply tap into the two leads to attach your new antenna. There may be polarity, so make sure you stick with white-to-white and black-to-black. Also recommend you use some sort of quick connector for your new shield wire when you attach it to the white and black lead at the existing fob antenna.

 

[Dborn]

Check the battery in the fob. Ensure phone is nowhere near the fob. The phone does interfere. I have power lift gate, and never had an issue approaching from the rear.

 

[SDRick]

As I mentioned up thread, the service center did replace the battery for me (without measuring the voltage). In my situation, this did not help as the original (one month) old battery showed over 3 V when I brought it home to measure.

The service center agrees that the rear sensor is probably the culprit. Unfortunately, they are backed up for minor things until September 15. I would have to agree, it is somewhat minor and I am not sure if I want to bring it in just for this. Most probably it will require removing the rear bumper and either checking the key fob antenna connection or replacing it. Lots of time and aggravation for a little antenna.

 

[jcaspar]

Exactly how mine works.

I thought I was clear.

There is a sensor at the rear which, if it detects a key, will allow you to hit the manual trunk latch on the vehicle allowing you to open the hatch. Once the trunk is latch is operated, the door handles are unlocked and, if set to auto-present, they present themselves.

The handles will not auto present from the rear sensor until you operate the manual latch.

 

[SDRick]

AK,

Since it looks as though my bumper will have to come off for the repair I am wondering while they are in there, would it make sense and would it be possible to add another antenna lead going toward the charging port? Would that accomplish the same thing you did except routing the wire from the back?

SDRick, The fob antenna was about $ 25.00 Installation took about 30-45 minutes. I played around with where to run my wire, up the headliner or down and along the door sills. Settled on door sill areas. Once you get past the rear door sill, you must tuck the wire along the trim and behind the upper seat belt anchor point and around the parcel shelf plastic bracket. I know someone else on TMC that did it too. We both recommend you use shield 1 pair cable. The front door fob antenna is at the end of the dash (on both sides) attached to the sort-of-triangular trim at the end of the dash. (The door panels covers this trim when the door is closed.) You simply tap into the two leads to attach your new antenna. There may be polarity, so make sure you stick with white-to-white and black-to-black. Also recommend you use some sort of quick connector for your new shield wire when you attach it to the white and black lead at the existing fob antenna.

 

[Akikiki]

SDRick, Me? I would not. Bottom line: I don't think it will help you to add a fob antenna at the liftgate fob antenna.

Here's why. I only have my idea of how this works because I've not seen anything else explained. I think the liftgate unlock fob antenna circuit goes to a different sensor or release trigger. Here's how mine works. When I move my fob close to the trunk release, there's no sound to indicate something unlocked. And not until I press the trunk release and the liftgate starts to open does the front and rear door handles present so I can see the doors are unlocked. If I am seeking to unlock the car doors, I don't think it is practical to open the liftgate to get the door handles to present and the doors unlock. And the charge port does not unlock until the doors are unlocked, not the liftgate fob antenna senses the fob is near.

 

[SDRick]

I finally discovered a huge clue as to the variability of the rear hatch sensor working or not. Whenever the car goes into full sleep, the rear hatch sensor will not allow the hatch to be opened manually.

Naturally, in full sleep, the doorhandles will present when the key fog is in proximity. Whenever the car is in idle mode, the key fob sensors/antennas work properly.

So far I have not received an adequate! Service center. Does anyone have a theory?