Edit: the rear inverter on these is way more integrated into the EDU than the Model3/Y/Late S/X that I've worked on. I now understand the reason why no one appears to sell just the inverter.
Also Tom, theoretically you could drive it FWD, BUT you would have to find a way to do two things:
1) Remove the RDU, loop the coolant lines, and remove or disassemble the CV's. *Or* Isolate the motor phase cables from the inverter and from other things as the rear motor will be generating a voltage as you spin it. Edit 2: the rear motor on these early S's (and X's) are induction and therefore you don't need to worry about electrically disconnecting the thing at all (other than point 2) and it even has a mechanical oil pump so you could theoretically just let it be dead weight. Theoretically this means the car can be flat towed unlike a lot of EVs.
2) convince the car's brain that the rear drive unit doesn't exist to clear faults and allow it to actually go. There is a very slim chance this it is possible to trick the car into thinking it's a RWD version, however the BCM/HV electronics are probably different between 2WD and 4WD Model S's. But someone with the right laptop (likely filched from a Tesla controls lab) could probably do it. TC/ESC and ABS might be wonky.
Original comment:
I can almost guarantee that if it is in fact an issue in the rear drive unit and not a BCM or DC-DC converter failure tripping faults in other modules, that the rear PCM/inverter and not the entire drive unit would be the thing in need of replacement. There's no way an electrical fault comes along with needing to toss the gearbox and motor along with it. When your ECU on a car goes bad, you typically don't just swap the whole engine right? This car just happens to have one of its ECUs bolted to the gearbox opposite the motor.
Now, I have no clue if that module can be simply swapped without a scanner or laptop to tell the car to be ok with the new PCM, but even if it does it's my understanding that there are tools available nowadays to reflash these cars. It would be the same if you swapped the entire rear EDU (electric drive unit - motor/gearbox/inverter lump at the business end(s) of an EV ). Anyway, the rear inverter/PCM (different places will call them different things) is where I would start with shopping and figuring out the logistics of repair.
Boost_Crazy said:
In reply to Tom Suddard :
Chris didn't "merely mention the fact that the brand is extremely controversial now." That would have been completely appropriate, and doesn't indicate a position on the topic. He said "It hadn’t yet become associated with the systematic disassembly of our government." Those are not the same thing. One is biased and invites a counter argument, the other does not.
Respectfully, you are reading far too much into the comment you quoted. Both are factual statements. "Systemic disassembly" is certainly an apt descriptor of what is happening, as trumpeted (ha ha) by Musk and others themselves. As an outside observer, I think "systemic disassembly" is a generous phrase, and many others that are far more loaded could certainly apply.
In reply to ZOO (Forum Supporter) :
More Politics.
Can we just stick to discussing cars again.
A neutral statement could have been: "the CEO has become entangled in the politics of the day"
Edit: The main contributors over in the Ukraine / Russia thread are VERY good at discussing sensitive politcally charge topics while just stating the facts of the situation without interjecting a slant one way or the other. I find the neutral tone in that thread refreshing.
Indy - Guy said:
In reply to ZOO (Forum Supporter) :
More Politics.
Can we just stick to discussing cars again.
To be pedantic, we were discussing language :), but there is certainly no doubt that the two are interwtined. I didn't assert a position, other than make the clear observation that far more powerful language could have been used. For example, rhetoric over cutting useless bloat and excesss. Or rhetoric over ignoring the checks and balances of the consititution. Any inference from my statement is likely based on the reader's politics, not mine.
But I agree, this is about the cars. I'd be inclined to walk away from the Model S. Recoup whatever cash I can for a broken car that needs a drive unit.
After further research I think the most GRM thing to do is to swap the whole rear subframe and suspension with one from a 2020+ Model S so that you can use a Model 3/Y style EDU which would save you negative dollars but are a technically superior design. And hey, it's not my money I'm spending here.
These early Model S EDUs are full of engineering decisions that today would be hilariously questionable (mostly because these cars sort of pioneered the way for us all to learn the do's and don't's for mass production EV success).
bumpsteer said:
After further research I think the most GRM thing to do is to swap the whole rear subframe and suspension with one from a 2020+ Model S so that you can use a Model 3/Y style EDU which would save you negative dollars but are a technically superior design. And hey, it's not my money I'm spending here.
Hm. Actually, I think the most GRM thing to do would be to swap in an Chevy V8. :)
A couple of V8s wouldn't fit as well as a couple of K24s. 
In reply to Tom Suddard :
So...GRM project car? 
Crazy thought: What would it cost to have the dealer or shop install a new or reman engine in my 2014 Civic Si? I have a bad feeling it’s close to the Chris’ quote....
In reply to David S. Wallens :
The last reman I had installed was $4200. That was a 4.2l in a F250.
I can tell you that a M Sport BMW X5 engine is $27k.
Looks like a reman K24 is about $4500. Used they are about $1500.
Price an engine and trans replacement on any comparable ICE vehicle and take a look at the cost. Your bill is not that bad.
The local Hendrick Chrysler dealer wanted almost $5k to replace two front driveshafts on a 2019 Pacifica. The owner and I ordered two shafts online and are doing it ourselves, so I get that part of it, but you knew you couldn't do a lot of these repairs when you bought the car, right?
I second the previous comment about the Porsche transmission adventure.
Upcoming trip? Rent a car with unlimited mileage, rather than rush an expensive repair.
The political comments are completely irrelevant and easily foreseeable as problematic to a very large portion of your readership. Translation: they should have been edited out.
Tom1200
PowerDork
2/26/25 2:35 p.m.
At best you're looking at $1000 in net savings by installing a used part which may or may not fail.
In reply to Tom1200 :
Tom and I talked a bit about doing it in the shop and yeah, for the $1000 of labor its worth it to have them do it for me. That way we can spend the time and lift space that it would be taking up to work on other project cars.
One of my favorite parts of GRM is that you stick to cars and leave the politics out. This is strike one (from a 30+ year subscriber).
"It hadn’t yet become associated with the systematic disassembly of our government."
That $1,000 is for sure better spent on having the shop install it. It's not just the time savings in that you'd have to suss out how to do it yourself, nor is it the space savings on the lift or in the shop (particularly if you found out you needed a specialized tool). It's really the warranty: If the shop is doing everything, they are the warrantor of the entire job. Any fault whatsoever? It goes back. If you installed the drive unit there would always be the "what-if" and disputes on potentially incorrect assembly (be it improper torque values, improper alignment techniques, whatever) were something to go awry.
To avoid all of those headaches for $1k?
Money well-spent.
Tom1200
PowerDork
2/26/25 2:57 p.m.
With all due respect to the fine staff at GRM. This is a place of escapism for most of us.
When you choose to insert politics of the day you devalue that.....................
Please keep this in mind.
Sounds like you bought a $19000 Tesla. (ducks and runs for cover)
In all seriousness though that sucks.
I sort of thought (and I know this is crazy) that there would be less to go wrong in an EV, less moving parts and all compared to an ICE car. I'm now questioning my logic. Maybe my thinking ought to be something more like: it's less to go wrong, but when it goes wrong, it really goes wrong.
I would say 19k for a Model S is pretty damn good, and it is. The one I drove was a monster! AND I'm a bit concerned about the longevity of the cars given this story and others I have heard about manufacturing quality.
In reply to CyberEric :
It's not so different to, say, what can happen to a BMW with a certain generation of Valvetronic when the valvetrain rack jams. That can be five figures to repair because it takes out the engine controller in addition to the mechanical issues.
Or, say, a Ford with a washer fluid pump that leaks into the connector, which forces corrosive washer fluid under into some rather sensitive electronics, and takes out a lot of wiring along the way.
I'm trying to think of another good one where a simple minor issue causes all the money to fall out of your wallet. A failed oil pump belt on anything with an Ecoboost three will probably cost more than the Tesla did to return the vehicle to self-mobile status. (How about slipped sleeves in a Rover engine?)
I learned from experience that Delphi-manufacture ignition coils can fire prematurely with computers calibrated for Bosch ignition coils. Because I learned from experience and not reading from a book, this cost me... a lot of money, after buying three complete engines and rebuilding one. Fortunately this was in 2020 so it's not like I needed the money for motorsports.
In reply to CyberEric :
There is less to go wrong, so it's more likely to be a major issue when something is wrong. I had to get my charge port ground cable tightened 3 times. I could drive the car, but tons of error messages and couldn't charge. It's sort of like a return line on a gas tank vent not working and you can't fill it with gas.
bbbbRASS said:
In reply to CyberEric :
There is less to go wrong, so it's more likely to be a major issue when something is wrong.
Simpler is more reliable, but as you point out, it also means less redundancy so any problem is major.
This is what I love about GRM. Any other online forum and I'd be bracing myself for the tired "See, told you EVs suck! My 2nd cousin says they're worse for the environment, and built by child laborers, and they spontaneously combust and burn down entire counties!" GRM forum members are like "Hey, that's cool. 700hp! Let's make it a project car. Check out this resource. Try this!"
@Pete, right that makes sense thanks. I'll admit, my thinking doesn't go to those issues with an ICE. I think what I am trying to say is that I was hopeful about less maintenance with EVs because of (perhaps my story and not true) less complexity. Now I feel less hopeful.
Edit: seeing your post about the rotary, yep, point well taken.
@bbbRASS, totally. Makes sense.
