2014 Model S "Powering off" when walked away from, doesn't recognize key fob or app

[Jaydork]

Hello,

Without diving into every detail, it seems my recently acquired Model S is going "full shut down" at random times. Locked out, doesn't sense key fob or app etc. So far my only "fix" has been to keep a window cracked to "break in", pop the hood manually and literally just tap/flick the 12v positive line. Sometimes it takes more time, but this morning was the fastest yet, whereas yesterday I spent 10 minutes on my lunch break pushing on fuses and wiggling the wires before it popped on.

Audible click can be heard, then the car goes through a boot up sequence as if I had done a system reboot. Generally no problems after that... until there is a problem. Haven't had the issue happen at work once yet, and hasn't happened while I'm out and about running errands. So far only at my house (before and after connecting to wifi), and at my girlfriends house (also before and after connecting to wifi).

App doesn't really do anything other than indicate occasionally that it's connected it again. It may connect and update every couple hours, or the app may go over 24 hours without "seeing" the car. It'll prompt updates when connected, and so far the updates have been going through, but nothing has stuck to actually fix this issue yet.

Originally I thought it was a data connectivity issue as it never seems to have great service (usually connects after driving for a bit, but almost never more than 1 bar. Wifi works fine/mobile hotspot). Now I'm leaning more towards "something" that's causing it to full power down where it's not even passively looking for a signal (phone, key fob, remote access from Roadside Assistance etc).

 

[maximizese]

What year is the car, battery pack variant, MCU1 or MCU2, was the car ever in an accident, how old is the 12V battery? Reason I ask is because our 11/13 built S85 was just fine until around 2019 when the newer operating system became too taxing for the MCU1. We'd have audio system stuttering, random reboots while in motion, and long 3-10 minutes waits to boot up the car. MCU2 upgrade was huge improvement but about a 1.5yrs after getting it, we experienced 2 random reboots while in motion. Just yesterday, it took the car about 20 seconds to respond to the key fob. Not sure if the fob battery is low or if the car is glitchy. I plan on doing the latest FW update tonight to see if that improves my situation.

 

[NewbyMaybe]

Put a meter on the 12v when it doesn't want to startup.

 

[Jaydork]

What year is the car, battery pack variant, MCU1 or MCU2, was the car ever in an accident, how old is the 12V battery? Reason I ask is because our 11/13 built S85 was just fine until around 2019 when the newer operating system became too taxing for the MCU1. We'd have audio system stuttering, random reboots while in motion, and long 3-10 minutes waits to boot up the car. MCU2 upgrade was huge improvement but about a 1.5yrs after getting it, we experienced 2 random reboots while in motion. Just yesterday, it took the car about 20 seconds to respond to the key fob. Not sure if the fob battery is low or if the car is glitchy. I plan on doing the latest FW update tonight to see if that improves my situation.

2024, Unknown battery back, not 100% but pretty certain MCU2, no accidents, and don't believe 12v has been replaced. I bought it from our companies owner 1 week ago today, and oddly enough no issues since first start yesterday morning for work. Still had to pop the hood and wiggle the cable, but no issues since then (so about 30 hours with 6ish starts and stops in the time).

On a hardware side, my speculation is poor connection for the 12v positive line, and maybe the 12v itself. On a software side, I wonder if it's a ownership transfer issue? The app implied I'd need proof of purchase and valid ID, but once the previous owner entered my tesla account info, app just started working without any of that "required" stuff.

I have had a couple updates applied since the purchase, but individually none of those seemed to have an "immediate" change, as it was still happening after the updates, though now it's been fine (so far) also after the updates.

Put a meter on the 12v when it doesn't want to startup.

Planning to next time I'm having issues, just need to have a meter on hand to use.

 

[NewbyMaybe]

Smart phone voltmeter dongle possible? Doubt I'm the first to think of it.

 

[Jaydork]

Going to run a voltage check this week, but after 2 weeks, the issue seems to so far only happen at my girlfriends house. No issues with cell service or wifi connection, but anywhere I actually drive it, go in and out of a store, works fine. Park it at her place though, and it's a coin toss if it'll work without the black magic of "wiggle some cords" till it clicks on.

Her friend came by and car wouldn't open when I walked up to it, but gave her the key while I ran inside and it opened for her no problem less than a minute later.

While I can still see it being the 12v, I don't understand how it could be since I'd expect the issue to be somewhat repeatable if it were a connection or low voltage issue. Parked at MY house overnight, wakes up immediately in the morning when I leave for work 4 days in a row. Day 5, after getting off work and going back to GF's house, next morning it again won't (usually) wake up immediately.

The location seems repeatable, but no other way to re-create the issue to narrow down what it may be. Ultimately so long as I can get inside the car to pop the frunk, it's max 5-10 minutes before it'll click on and be driveable. Just nervous to actually roll the windows up and end up being fully locked out.

 

[Jaydork]

Put a meter on the 12v when it doesn't want to startup.

Possible I'm a moron, but tried checking the voltage by removing the front sensor bumper and got... 000 on the reader. Popped my other car's hood and checked the battery there, immediate reading and no issues.

Yesterday I came home from work for lunch, and on my way back, door handles all popped out, opened the driver door, and within a second of opening the door the car died and wouldn't let me open the other doors (handles stuck extended, but car locked). Same problem, but has only happened once like this before where it clearly "works" and right in the moment just shuts down. First time took about 10 minutes of the usual "wiggling", but this time i've spent collectively about 1 hour between yesterday and today with no luck.

To tie it all back, the car was sitting "dead", when I ran the voltage meter, so not sure how that may play into it. I'm assuming I would still get a reading since the 12v powers the sensors and such to recognize the key fob when it's close?

It was suggested by a mechanic at work (i'm at an airport) that there could be a ground issue somewhere, and I've just been getting lucky that sometimes it gets a connection, and other times, simply opening a door might be enough to short the connection again. I think that would line up with getting no reading from the pins behind the bumper? If the circuit is bad with a loose ground, would that cause a 0 power reading?

Service appointment for Tuesday, though going to be tough to get to if I can't drive myself there in the car. I'm in the middle of moving and the appointment is 65 miles away where I'm moving to.

 

[NewbyMaybe]

There's a ground post under the frunk tub but the "wiggle" factor means the problem is on top.
If you look at a video for changing the cabin air filter then you will be able to see what's loose.
Sometimes the 12v doesn't last long if the car sits a lot. How old is it?
The fireman's loop may be what you are wiggling, be sure it's connected good. It's a plug that's meant to be pulled apart in an emergency.

 

[Jaydork]

There's a ground post under the frunk tub but the "wiggle" factor means the problem is on top.
If you look at a video for changing the cabin air filter then you will be able to see what's loose.
Sometimes the 12v doesn't last long if the car sits a lot. How old is it?
The fireman's loop may be what you are wiggling, be sure it's connected good. It's a plug that's meant to be pulled apart in an emergency.

Yes, the fireman's loop tends to be the most consistent. I was using the +/- posts in the funk tube for voltage check originally. Just need to get my set of wrenches to remove the air filter mount to access the battery. I'll confirm with the prior owner (family friend), but he didn't mention battery (or anything really) having been replaced. Not so much "suspicion" as just "difficult to reconcile coincidence" that he's had no problems with it for almost a decade, and 6 hours after I buy it I'm having these sporadic issues.

I guess it could be possible that it sat a while (he's got other, newer Tesla's), and worked when he drove it to work where I bought it, but was already dying and he would have potentially had the same issue either way.

Ah well, I'll update when I'm able to get access to the actual battery.

Thanks!

 

[NewbyMaybe]

Putting a slow charge on the 12v posts behind the nosecone could help.

 

[Jaydork]

Update - sadly, no clear culprit, but after 2 full days of nothing working, got my tools this morning and "worked my magic".
Before I ever even touched the 12v, as soon as I removed the air filter housing to gain access, it immediately clicked on.
Can confirm voltage reader shows no issues on the 12v when attached directly to it. Worth noting that the frunk pins also now show the same reading. Difference between now and first time is the car is actually powered on vs when I got the 0 reading, it was in the 'lockout" mode.

It's got another software update, but I doubt that will do anything for the particular issue. Mobile service appointment in 2 weeks, probably still need to keep that since no clear signs of "here's a fix".

 

[NewbyMaybe]

Connect the meter to the nosecone posts with clips or tape and move the connections at the battery.
Check the 12v after the car has been shut down overnight without waking it up.