FRONT TRUNK SENSOR ISSUE!

[swedge]

Probably the same problem as the original post, an intermittent false frunk open indicationon my 2021 Model Y.

Mobile service tech just fixed it, we hope... . The tech said this was the first time mobile service did this repair, as previous such repairs were done at service centers.

The fix was to replace 4 tiny screws, but now with lock washers, so as to improve the electrical grounding. Sounds quick, right? Sadly the 4 screws are inside an electronics box, which is fastened to the fire-wall behind the 12V battery. That box is where all the front end sensors and actuators connect, and those four tiny screws hold the circuit board in place and also provide an electrical ground path. Replacing the screws was trivial, but it took a couple hours to gain access to the box, remove and reinstall it.

The tech explained that Tesla used to use micro-switches for various door and trunk latch sensors, but those often failed. So some new type of sensor with an electronic interface is used now, but apparently this is sensitive to poor grounding in the interface box. He said there had been numerous frunk latch replacements only to have the problem return. Engineering finally figured out the problem was never the latch or sensor, or software, but rather poor grounding of the interface electronics.

So far my car seems to be fixed, but the false indication happened only once in a while, so I'll just have to watch and see if it ever happens again. I will post an update if the problem recurs.

 

[swedge]

Mobile service tech just fixed it, we hope... .

I am now very uncertain if this worked. It sure would be nice if mobile service can fix the intermittent frunk open indication, but my case may have gone sideways.

The day after the "fix" the car went catatonic in a parking lot after a lunch stop: no iPhone unlock, no key-card unlock, no app access. A mobile service tech came out soon, but he could not even open the frunk to re-boot the car. A total lock-out. So a tow-truck was called and they had to use dollies under the tires to take it to the service center because the car was locked and stuck in Park, i.e. wheels locked and transport mode inaccessible. It is spending the weekend waiting in the service wait queue, so hopefully I will get a diagnosis on Monday 5/10.

It drove and acted OK for a couple drives after the frunk latch "fix", so I don't know if this is related to the fix or not. The mobile tech said something about the car having logged an error regarding out of sync software versions among the cars various modules, so maybe a re-load of the software will resolve it. Fingers crossed... I will update when I know more.

SW

 

[Jabnlab]

I am now very uncertain if this worked. It sure would be nice if mobile service can fix the intermittent frunk open indication, but my case may have gone sideways.

The day after the "fix" the car went catatonic in a parking lot after a lunch stop: no iPhone unlock, no key-card unlock, no app access. A mobile service tech came out soon, but he could not even open the frunk to re-boot the car. A total lock-out. So a tow-truck was called and they had to use dollies under the tires to take it to the service center because the car was locked and stuck in Park, i.e. wheels locked and transport mode inaccessible. It is spending the weekend waiting in the service wait queue, so hopefully I will get a diagnosis on Monday 5/10.

It drove and acted OK for a couple drives after the frunk latch "fix", so I don't know if this is related to the fix or not. The mobile tech said something about the car having logged an error regarding out of sync software versions among the cars various modules, so maybe a re-load of the software will resolve it. Fingers crossed... I will update when I know more.

SW

View attachment 660854

Any update on your issues? My frunk warning has reappeared. Had the latch replaced in Sept which didn't fix it. But then it went away when it got cooler untill today when it got hot again.

 

[swedge]

Any update on your issues? My frunk warning has reappeared. Had the latch replaced in Sept which didn't fix it. But then it went away when it got cooler untill today when it got hot again.

Jab,

My Model Y is still at the Service Center awaiting a part. According to my service advisor, it appears that when the mobile tech did the 5 grounding screws fix, he made an error during reassembly and pinched some wires. This resulted in the lockdown of the car. I do not know how the Service Center got it open, but apparently they did.

The crushed wires were repaired on the Tues after the late Thursday tow-in. However, the SC decided to perform a service bulletin regarding PT sensors in the heat pump. Alas, when that was tested, problems were found which required replacing the expansion valves, parts which were not on hand. The current estimate is "maybe" Monday 5/24.

So, I have still not been able to confirm the fruk issue is fixed. Even if I do get my car back soon, as you and others have experienced, working for a few days will not prove that this intermittent problem has been resolved. But my hunch is that the 5 grounding screws replacement actually will fix the intermittent false frunk open indication. The intermittency, apparent temperature sensitivity, as well as the obscurity and cost of the fix are all consistent with Tesla engineering having located the root cause and proven this remedy for the problem. Carried out by a service tech experienced with the procedure, it should take only a couple hours and should not cause further damage.

As for the PT service bulletin, until mine is fixed and tested, I can not recommend allowing that to be done right now. The purpose does appear to be an important reliability issue, because the heat management system is not just for cabin comfort, but also battery, motor and electronics temperature control - failure could make the car un-drivable. But, in my case replacing the PT sensor seems to have exposed other problems in the system, and those components appear to currently be in short supply.

SW

 

[swedge]

swedge said:
Mobile service tech just fixed it, we hope... .

I am now very uncertain if this worked.

The day after Mobile Service installed 5 grounding screws in my Front Body Controller Module, the car failed completely, see my post above, FRONT TRUNK SENSOR ISSUE! and/or Dead Car

It turned out that the mobile tech accidentally crushed part of the wiring harness when he reinstalled the module, which caused the car to go dead, but apparently also caused damage in the controller module. So even after the wires were repaired, the car gave various erroneous error messages which led the service center techs on various wild goose chases. After several slow parts deliveries and fruitless replacements they replaced the controller module which cleared all the errors. The car was out of service for 21 days, and I picked it up yesterday.

I am now watching to see if the false front trunk open indication recurs. This never occurred often or consistently, so it will take a while to be condfident that it is fixed. I was told that the new controller module does have the corrected grounding screws, a fix which others have reported is effective, so I remain cautiously optimistic.

How could this fix possibly work? Here is my hypothesis. One tech told me that Tesla had reliability problems on earlier Tesla models with "micro-switches", and now use some other type of sensor for doors, hatches and trunk lids. My guess is that Hall effect "switches" are a likely alternative, and while these solid-state devices are extremely reliable, they may have less robust signaling than a mechanical switch. Perhaps electrical noise in the controller grounding, i.e. spurious voltage variations, is what was triggering the false indications. Pure speculation here, but it would explain why it took so long for Tesla to figure it out and why adding lock washers to five tiny screws could vanquish these phantoms.

Assuming mine is really fixed, and assuming that Tesla Service propagates the lessons learned from my case, mobile service should be able to reliably fix the false open trunk warnings. My fingers remain crossed. I will update this if the problem recurs.

 

[Jabnlab]

The day after Mobile Service installed 5 grounding screws in my Front Body Controller Module, the car failed completely, see my post above, FRONT TRUNK SENSOR ISSUE! and/or Dead Car

It turned out that the mobile tech accidentally crushed part of the wiring harness when he reinstalled the module, which caused the car to go dead, but apparently also caused damage in the controller module. So even after the wires were repaired, the car gave various erroneous error messages which led the service center techs on various wild goose chases. After several slow parts deliveries and fruitless replacements they replaced the controller module which cleared all the errors. The car was out of service for 21 days, and I picked it up yesterday.

I am now watching to see if the false front trunk open indication recurs. This never occurred often or consistently, so it will take a while to be condfident that it is fixed. I was told that the new controller module does have the corrected grounding screws, a fix which others have reported is effective, so I remain cautiously optimistic.

How could this fix possibly work? Here is my hypothesis. One tech told me that Tesla had reliability problems on earlier Tesla models with "micro-switches", and now use some other type of sensor for doors, hatches and trunk lids. My guess is that Hall effect "switches" are a likely alternative, and while these solid-state devices are extremely reliable, they may have less robust signaling than a mechanical switch. Perhaps electrical noise in the controller grounding, i.e. spurious voltage variations, is what was triggering the false indications. Pure speculation here, but it would explain why it took so long for Tesla to figure it out and why adding lock washers to five tiny screws could vanquish these phantoms.

Assuming mine is really fixed, and assuming that Tesla Service propagates the lessons learned from my case, mobile service should be able to reliably fix the false open trunk warnings. My fingers remain crossed. I will update this if the problem recurs.

Thanks for the update and I'm glad you finally got yours back. Fingers crossed the fix works. Mine only acted up that 1 day and hasn't reoccurred but I'm sure it will resurface again soon. It only happened when I was parked so it didn't set the error code, but as soon as an error sets I'm going to put in for service.

 

[swedge]

Not solved! My car is still occasionally showing the front trunk open when it is not.

This after 22 days out of service due to a mobile service error while replacing grounding screws. Eventually the front body controller module was replace with a new one which I was assured had the proper grounding screws. But after all that the original problem persists.

Fortunately, actually opening and then closing the frunk cleared the error, and it has not occurred while driving.

The front trunk lid was closed and latched when the photo below was taken.

Given the chaos in the service center, I would not say this means the grounding screw fix does not work. If it is ever reliably fixed, I'll post again.

SW

 

[Jabnlab]

Mine started acting up more often now so I scheduled an appointment for next week. No option for mobile service so I'll be taking it to the SC (first time too). I'm going on a road trip in September so I'm hoping to have it resolved by then. I definitely don't want it preventing me from using autopilot on a long road trip, lol

 

[Jabnlab]

Just picked my Y up from the SC (Peabody, MA) and they did the hood latch ground overlay as well as the ac sensors. I'm 99% sure its fixed, the 65 mile ride home was the ideal temperature for the frunk to act up and it didn't so its looking good.

The sc was great too other then the little bit of grease they left on my white seats, but I always have baby wipes in the car.

 

[krunal.amin]

Recently received our new MY FSD AWD w/tow hitch 18xxx on 6/25 - we've been having issues with the front trunk giving alerts that the trunk is open even though it's latched. I had a recent mobile service tech visit on 7/15 to address this along with other fitment and alignment issues and am still getting the incessant warning/alert that the front trunk is open. I made another mobile request (pic attached) and it was just recently cancelled by mobile service due to the fact this is a firmware issue - so WHAT exactly does that mean??? This is the 2nd attempt to get this fixed with no resolution! I'm about to call a LEMON LAWYER Attorney here in California, as it states after 3 recurring issues of the same problem, can warrant a full refund or exchange of the vehicle for a like in kind.

This is a dangerous situation while in FSD or TACC as it disables both functions when the notification pops up! Also, while in park, will not allow you to go into Drive unless you press Ignore on the screen! Having paid for FSD and the inability to use is frustrating in itself, but getting a notification while on the freeway at freeway speeds is very unnerving!

Has anyone else had this issue? If so, what was done (if anything) to resolve? Thanks in advance for any advice!
View attachment 567171

I have the same issue, it has been in shop for more than 3 times... I will be pulling LEMON LAW on this one. Model Y, purchased July 06, 2020.

 

[exchguy]

I have the same issue, it has been in shop for more than 3 times... I will be pulling LEMON LAW on this one. Model Y, purchased July 06, 2020.

Any updates on this? I have had frunk sensor replaced in June, I also have a LR 2020. Already getting more warnings about Frunk sensor. So this would be the 2nd time.

 

[rxlawdude]

Any updates on this? I have had frunk sensor replaced in June, I also have a LR 2020. Already getting more warnings about Frunk sensor. So this would be the 2nd time.

One and done poster. Doubt he will ever return.

 

[Banter99]

Model S . 2022 March delivery. Same problem - Front trunk open warning. You would think they would have resolved this by now. Limits the speed to 24km. Warning keeps beeping. Have service appointment. Not confident to take it on the highway. Very disappointing. Open and closed the frunk number of times. No go.

 

[swedge]

One and done poster. Doubt he will ever return.

Five posts, actually. Sorry I didn't post the resolution, but it takes a while to be sure that an intermittent problem is fixed.

It was eventually fixed. After several tries and a long delay caused by a deer strike, canceling an appointment while waiting for parts, eventually I got it in to the Berkeley service center. I explained the many, many days of unsuccessful "repairs", and suggest that this time they apply every "known" fix: the Front Body Controller, the front latch mechanism, and the wiring harness replacement. They appear to have don't eh first two of these. We have not had the problem since. Of course, the shotgun approach obscured which fix did the job, but I was ready to discuss lemon law limits on how long they could take to fix a problem. So they did.

All I can suggest is that folks with this problem have their service center contact the Berkeley Calf center and look up my case. I'll attach the invoice below.

SW

 

[Banter99]

Model S . 2022 March delivery. Same problem - Front trunk open warning. You would think they would have resolved this by now. Limits the speed to 24km. Warning keeps beeping. Have service appointment. Not confident to take it on the highway. Very disappointing. Open and closed the frunk number of times. No go.

Got it serviced today. Was told "Replaced the front hood latch." All good now.

 

[swedge]

Got it serviced today. Was told "Replaced the front hood latch." All good now.

Hopefully that fixed it! If it recurs, others have has success after the front body controller was repaired or replaced, or a wiring harness was replaced or repaired.

Fingers crossed they got it.