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Ground Stud Nut over torqued

2 weeks ago my right headlight started failing. So I ordered 2 HID D3S bulbs on Amazon and scheduled to tackle that job this weekend. The last Wednesday I get "Coolant low" message. Made appontment with Tesla service but was assured not to worry - probably a bad ground. The I got intermittent 3 beeps with a message flashing on the IP and main screen but not long enough to read. Also "Suspension needs service popped up frequently. I got worse yesterday while driving in the morning. In summary the following happened intermittently:

- message: Coolant low ( just when starting car )
- right headlight not working
- right turn signal intermittent ( for about 20 minutes, then working)
- message: Suspension needs service ( on permanently until full power off, then re-appearing)
- message: front trunk lid open (this was the 3 beeps and message happening frequently)
- phone notification: Car alarm has been triggered

I thought that there must be some commonality to this, like a bad ground. I removed the Frunk tub and Voila! a broken ground lug / stud merrily swinging in the air. Looks like too much torque was applied at the factory.



Drilled into the broken stud and tapped a thread

Then sandpapered the stud and brass lug connected to the 2 wires. Temporarily connected a jumper cable to the brass lug and low and behold the headlight worked and all warning messages disappeared.

Went to Hindle's Hardware in Clarksburg Ontario ( that is in the area where I was visiting ) and got a brass bolt with 2 nuts and special electrical paste for joining dissimilar metals. Reason for brass bolt is that the lug on the 2 wires was already brass.

That Hardware store is amazing! Right out of the 30's complete with crank cash register. If he doesn't have it then it doesn't exist.

Here is the finished job. All problems were solved by this including the malfunctioning headlight.


Total cost of repair CAD$ 5.20 ( and 2 beers and my time )
Interesting ... I'm having the exact same symptoms as the OP plus my air suspension started to act up and auto-pilot is off line. Weird how this issue affects the right headlight and signal. I'm sure it is a ground in my case too ... symptoms are a perfect match to the OP! In my case the ground stud seems fine though ... not sure where to look next :( ... I tested the circuit and even tried an extra ground cable on it ... no dice. I guess Tesla can figure it out. S85D March 2015. I'll add to this post once I figure it out ...
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Reactions: croman and Fiddler
OK - got it. I was thinking it was the battery ground. After looking more closely at the OPs picture, the problem ground is on the passenger side frame ... duh. Drilled, tapped, and used a steel bolt with di-electric grease. Will change that out to a brass bolt next time I'm at a hardware. Solved all problems including the air suspension. Any money this issue will be really common!!
My educated guess is that the stud sheared off due to over torquing at the factory.
yes that would maybe make it easier to sheer, but what is causing them to actually sheer?

They're welded into the frame, so perhaps there's flex in the frame that is causing it.

Weirdly all 5 of the respondants to this thread echoing the symptoms/problem the OP had are in Canada...
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Reactions: croman
I read this thread a few days ago but forgot about it involving a ground stud until I saw it just now again. Not a car person, and had not heard of this part before and Mr elbe's photos were great to illustrate. Anyway earlier today I posted to another thread here on TMC about an owner's ground stud that needed to be re-welded but the car in question had steering and braking issues among other alerts. Another owner posted they too had had their ground stud re-welded. Here's the link: Alert** loss of steering and braking while driving | Tesla Are all these type of problems coming from the same general location in the car (noticed 2 ground studs in the photo I think) or are there different ground studs in various areas around the car affecting different aspects of the car's functions?

Discussion in the above linked thread alluded to the fact that maybe the salt on the roads caused the deterioration or "rotting away" of the connection. I noticed that Mr elbe's location is in Canada so wonder if that could explain what happened to his ground stud. Could the cold temps be a factor? It does sound like a number of owners in Canada are having this issue. Don't know about the location of the OP in this other thread but one person who commented there with the issue was also from Canada.
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This is my first post on the TMC forum and want to start by expressing my immense gratitude to the OP for taking the time to provide all the detailed information. You cannot believe how happy I was to find your post when I had a whole range of strange problems and absolutely no clue what to do. Here is the full story:

I first encountered what I thought to be a minor problem with my 2015 Model S. It took about two weeks to escalate and it became a major issue on 23 Dec., thus just in the right time of the year… It all started as what appeared to be a computer glitch. As I was driving, an alarm sound was emitted for less than a second and an error message blinked in red on the screen. It was too brief to see and it just occurred once. Later, what was first an isolated event became intermittent but it was still too short to see on the screen what the problem was. Then, a few days prior to 23 Dec., one of my sons took our Model S for a short visit to our cottage (about 90 km from Montreal). He told me when he got back that he saw a low coolant warning and something about the suspension. Then, on 23 Dec. in the evening, as I was driving to my cottage, the right headlamp began to flash for a few seconds and stopped working soon after. A few kilometers later, the low coolant warning appeared and it was followed by the warning message (in full sustained red this time) that the front trunk (frunk) lid is open. I think that this warning somehow caused or what concomitant with all the exterior lights to go on and off a few times at this moment. I was on the highway so I took the next exit for an urgent unplanned stop. I check the frunk lid and it was properly closed. I made a reset of the main console and powered down the entire car afterwards. Everything appeared to be normal once this was completed, with the exception of the right headlamp that was still not working. I was able to reach my destination and I came back the next day during daylight. I had a few warnings but I knew the frunk lid was duly locked in position. The local service center was closed on that day (it was then Sunday just before Christmas) so I searched forums to see if anyone else had the same problem. We had family to visit and my car had to be in full working order. Thank God, I found the post with all the same symptoms and the solution! OP, you were (and you are still) my hero. Literally. I removed the frunk tub and exactly as you did, I saw the faulty ground stud. I have included a first picture of the whole front section for more context.


The ground stud initially appeared to be in place (see the second picture) but it was indeed broken. In fact, the parts on both sides of the terminal felt as soon as I touched the cable after I took the picture.


This, in my opinion, is not an over-torqued part but the result of a galvanic corrosion. I have my Model S since June 2015. It was manufactured a few weeks earlier so it was absolutely brand new when I took possession of it. It is thus currently its third winter and there are probably specific reasons that have contributed for the premature failure in my case. First, I travel mostly on highways and road salt is everywhere during the cold season. Secondly, my car is parked in a heated garage during the weekdays. I also have the presumption that a third factor is in play: We have automatic daytime running lights in Canada so there is current flowing all the time while driving. The daytime running lights on a Canadian Model S are only the peripheral LEDs and I always prefer the full lights all the time (I do this on all the cars I drive since I was 16 and I am now almost 50), so I switch the full headlights on or off manually every single time. Hence, there is more electric current running across the ground stud while I am driving compared to others. The rate of the degradation is abnormal but don’t get me wrong, I absolutely adore my Model S. The key issue here is that what happened to me will most certainly happen to others in a near future, if not a very near future. Everyone should have this checked sooner than later and pay attention to early symptoms. It can be fixed by the owner but not everyone has the tools to create a new threaded hole, aluminum washers and a proper brass bolt or screw (I had to dismantle an old pluming valve I had keep as a spare part to get the non-ferrous screw I needed), especially when all stores are closed or if the car is now out of order. As a side note, I have not seen such degradation on other ground studs.This appears to be a specific issue.

The car now works perfectly and we had a great time when we visited our folks.

That was my 2017 Christmas car story. Thank you once again OP!
Hey CanadianFromQC, a belated Merry Christmas to you and I am glad that my diagnosis and fix description helped you overcome the same problem. In hindsight, I also agree that it could be galvanic corrosion in association with the road salt getting everywhere. My next problem recently was the 3 aluminum bolts that held the power steering motor corroding and causing the motor to fall off.

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