Tesla Model S Grounding Stud (#P52)
[tiny update in #P52F1]
*IT Crowd emergency services voice* Has this…ever happened to you?
Well, probably not, nobody is driving old Tesla Model S’es. If however you do, and you get a sudden influx of weird and wonderful warnings that include the following, this blog post might help you out.
- frunk sensor suddenly shouts at you with MCU_u005_FrunkOpen, despite the frunk clearly being closed correctly – starts off with sub-second warnings that can barely be read on the screen, progresses to super-annoying intermittent contact where it beeps at you every second for a new event, up to full failure where the fault can be ignored once via button and then just persists
- low beams (Xenon) on passenger side are out, including a BC_W006_rightHeadLightFail warning about their malfunction – in advanced stages also the Xenon high beams might be unavailable and the LED daytime running lights may flicker or are off entirely
- horn isn’t working anymore, silent (ha!) failure with no error log entry
- cruise control unavailable, yet radar sensors and camera sign recognition still works
- (if fitted) air suspension does not self-level any longer, starting with “needs service” warnings, up to the back suspension going up to max setting for a very aggressive angle permanently (not going down at 50 km/h+) – super hard suspension setting and gets you stranded pretty soon if the system is leaking any air in the front
- cooling fluid level low THC_w0105 – “schedule service”, despite the reservoir being filled to spec
If all that happens simultaneously, not everything is going to shit all at once – it might very well be a grounding issue.
Check Tesla correction code 10102608, passenger side rail.
(thank you, WordPress, for once more making a useless downsampled version of uploaded images for the sake of saving space or some other bullshit reason)
This heavily oxidized piece of shit grounding stud is toast, and depending on condition, it might be acting as a resistor, so components attached aren’t getting full battery voltage, to insulating behaviour at least intermittently, to, well, being physically gone entirely. Mine was on stage two and, once attacked with a piece of steel, it became clear that there’s not much metal left and it’s a couple of potholes away from shearing off entirely.
There’s also a similar construction for parts on the driver’s side, but that is, according to the interwebs, unlikely to fail first. Which is a good thing, because apparently one of the components connected here is the power steering, which might be more of an issue than a flickering DRL assembly…
Touching the heavy ground connection with some bare metal, e.g. the towing eye commonly found in the frunk shell directly above, should NOT draw sparks and make the lights suddenly work again. If it does – well, there’s ya problem.
So, the fix is described in the Tesla document linked above – usually the thread cannot be re-used with just standard cleaning, so a new one is set in close proximity. Tesla recommends a rivet nut, but people also were successful in cutting the existing oxidized hole into the next size of metric thread, or just drilling a hole nearby and cutting threads there. Maybe even welding in a replacement nut will do – YMMV.
Not sure how much this costs at Tesla, but my local independent garage did this for a hundred bucks total for both sides in like half an hour. The THC_w0105 fluid sensor warning is still on, waiting on a Tesla appointment 100km and two weeks away to get that checked out – this might be unrelated, but the warning appeared at the very same time and also disappeared in the early stages as well. Reservoir is full, though, the usual suspects (triple and quad valves) aren’t leaking, cooling temps are as usual and supercharging works at full blast, so this might be a defective or to-be-reset sensor instead. We’ll see how that one goes.
[…] is a follow-up to #P52, the grounding stud issue of the legacy Model S. Technically, as of yesterday, all Model S are […]