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Drive unit or battery problem?
- Thread starter Nick70d
- Start date
JamstationP85D
Member
It may be your battery contactors and pyro fuse. That's what mine needed with those codes.
Didn't someone say the the contractors on the Ludicrous modles had the upgraded contractors? Hopefully the SC let's me know soon... I already miss the car!
The problem was the battery fluid heater. Getting the car back tomorrow.
I
"Service need, Car may not restart"
"Reduced performance. Acceleration reduced and regenerative braking disabled"
I called Tesla Roadside while in the car and they advised me to drive to my nearest Service Center before turning off the car in case the car does not restart. I did so and got to the Service Center 40 minutes before they closed. They never told me what was wrong with the car after checking the data logs, but they did the following:
replaced Drive Unit
replaced 12V battery
replaced HV battery contactors, pyro fuse, & HVAC drain hose
I later read that the drive units have been revised to ceramic bearings and HV battery contactors have been revised since my build date. They didn't tell me how much all of the repairs would have cost, but I'd be pretty upset if it was anything close to $9K. From my understanding, many of these drive unit replacements are refurbished/reconditioned drive units that are not all that complex to repair. My uneducated estimate leads me to think these units should be no more than $2K considering they are keeping the original unit as a core. Perhaps someone who has rebuilt a drive unit could chime in on the complexity, common points of failure, and input cost of refurbishment.
I had the original drive unit replaced on my 11/13 built S85 a few years ago at 90K miles under warranty. I brought the car in after I received the following warnings:
"Service need, Car may not restart"
"Reduced performance. Acceleration reduced and regenerative braking disabled"
I called Tesla Roadside while in the car and they advised me to drive to my nearest Service Center before turning off the car in case the car does not restart. I did so and got to the Service Center 40 minutes before they closed. They never told me what was wrong with the car after checking the data logs, but they did the following:
replaced Drive Unit
replaced 12V battery
replaced HV battery contactors, pyro fuse, & HVAC drain hose
I later read that the drive units have been revised to ceramic bearings and HV battery contactors have been revised since my build date. They didn't tell me how much all of the repairs would have cost, but I'd be pretty upset if it was anything close to $9K. From my understanding, many of these drive unit replacements are refurbished/reconditioned drive units that are not all that complex to repair. My uneducated estimate leads me to think these units should be no more than $2K considering they are keeping the original unit as a core. Perhaps someone who has rebuilt a drive unit could chime in on the complexity, common points of failure, and input cost of refurbishment.
One of the independent rebuilders charges ~$4k to refurb a drive unit. (Assuming no inverter damage.) I think they said that the cost for just the bearings, no labor, was ~$1,000. @ajbessinger can you confirm my recollection on that?
ajbessinger
Owner of QC Charge #2 (Portland OR)
Yes, our price to do a rebuild is $4k, assuming that the inverter is still good, and nothing else besides bearings/seals are damaged beyond repair. We have seen drive units with worn out splines, and messed up gears, which can't be fixed short of replacing the affected parts (which of course cost's more $). While we have the Drive Unit apart, we also make a number of modifications (including some custom fabricated parts) to the Drive Units as well to prevent damage from worn out coolant seals in the future. That $4k also includes all the work to drop the subframe from the car, remove the Drive Unit, then reinstall it, etc.
If someone wants to ship us a Drive Unit on a pallet, and we just do the straight up rebuild with the modifications, that brings the cost down to about $2,750. Unfortunately though, we can't test the inverter or anything if we have just the drive unit, so if it didn't work when it came out of the car, then it won't work when you get it back either, and if you need/want to replace the inverter, it will most likely need to be programmed, in which case we either need the car in our possession, or you have to see if you can find someone else that can do it... Additionally, if there were any codes stored in the car, they will need to be cleared out for the car to function normally again.
Clearing codes and replacing inverters often takes a lot of time and creates a lot of drama, which is why it's SO IMPORTANT to just check the rotor speed sensor regularly for the presence of liquid. I cannot iterate this enough, if you see even on drop of coolant on that speed sensor, and you want to save money in the long run, just get it rebuilt before you risk destroying the inverter! We have cars that have been at our shop for months because the inverters got toasted, but if the inverter is still fine, we can do a rebuild in less than a week (shop traffic allowing).
As far as just selling the parts alone, that's something you'd have to talk to the shop owner (Tony) about. It takes a number of specialized, and in some cases custom built tools to work on these drive units, so it's not necessarily something a "shade tree mechanic" will be able to easily handle on their own without potentially doing more harm than good.
Thanks for this additional piece of information. So the drive unit rebuild costs $2,750 and removal and reinstallation costs $1,250. That helps to understand where the costs are.
I'll go one further. The information about the common points of failure and preventative modifications is great knowledge for all Tesla owners to have, especially for those who plan to keep their cars beyond the warranty period. Tesla and technology in general are rather opaque so I greatly appreciate folks who can shed some light on the inner workings of these complex components.
I found this thread helpful as I am experiencing these codes and wanted to chime in. I am not a happy camper right now as the car has under 5,000 miles. I just purchased the car a few weeks ago. The previous owner babied the car and said Tesla recently changed the 12v battery as this has extended warranty. My saga began when I went to put the car into insane + mode. About 10 minutes after engaging insane + I left and the car gave the bms_035 warning only. However this disappeared a few days later when I went to drive the car and didn’t attempt to use insane + mode. Fast forward to today, I was going to use a supercharger and the preconditioning of the battery for a few minutes may have contributed to the bms_035 message resurfacing. After this I got the dreaded limp mode bms_u008. Also got the bms_w172. I think the bms_u008 fully took out regen and the car became hard to stop. The performance also sucked at that point. Build date was 11/2015. I cannot fathom the drive unit could be bad at 4900 miles. This seems crazy to me
Actually sitting is horrible on the seals. Then when your start driving it the seals wear fast and start leaking. I wouldn't be surprised if you have a drive unit full of coolant.
ajbessinger
Owner of QC Charge #2 (Portland OR)
I'd be willing to be that its a drive unit issue (or if not, it could be on the horizon). As @MP3Mike said, sitting can indeed be very bad for the drive unit seals, though they also wear out over time as well with more use, so its a bit of a catch 22... Overall though, just like any other car, I'd say its way better for them to be driven regularly than not. We actually just had a car in our shop that had less than 3k mi on a new replacement motor that was put in under a year ago with the seal already starting to go bad.
The good news is, your car should still be covered under its original powertrain warranty (assuming the car isn't salvaged).
Once your drive unit is taken care of, I highly reccomend checking your rotor encoder/speed sensor for the presence of coolant at least once a year, especially as your warranty is getting close to an end... Unfortunately rotor seal failures are part of the nature of the design of the LDU, and will inevitably happen on every motor sooner or later... Could be 5k miles, or 150k miles (I've seen plenty on both ends of the spectrum).
It's important to know that it's beginning to fail BEFORE the car starts throwing codes, as that opens up a whole new can of worms in terms of potential damage to the sensitive components within the drive unit (mainly the inverter). When we rebuild the LDUs at our shop, we add a drain kit to provide a way for coolant trapped in the drive unit to escape in an effort to protect the inverter. We also use an upgraded seal that is a triple lip variant like the original style (pre-2015) which are much less likely to wear out prematurely (the seals used in all LDUs since 2015 are a single lip style).
ajbessinger
Owner of QC Charge #2 (Portland OR)
Ah, makes sense. Must have developed an internal isolation fault. Not an uncommon fault on early battery heaters (though I don't know if I've ever seen on as new as 2015 fail). Regardless of whether or not the drive unit was the issue, you should still check out the speed sensor for signs of coolant! Even if just for peace of mind than nothing else...
VegarHenriksen
Member
I also have this exact issue with performance limit and no regen. Supercharging works fine, 12V is fine and brand new, battery heater has no problems heating battery. BMS voltages looks perfectly fine.
DU is from summer 2020 and is the Q revision.
BMS_u008_limpmode
BMS_ w172_SW_Drive_ Iso_Warning
DU is from summer 2020 and is the Q revision.
BMS_u008_limpmode
BMS_ w172_SW_Drive_ Iso_Warning
VegarHenriksen
Member
VegarHenriksen
Member
Yes. I was able to drive the car while the error was present and everything seemed to work fine
ajbessinger
Owner of QC Charge #2 (Portland OR)
Being a Q revision, it should have the upgraded hybrid-ceramic bearings (less likely to have noise issues), but will also have the inferior single lip rotor coolant seal (more likely to develop internal coolant leak). I would definitely check your speed sensor/encoder... The "Drive_Iso_Warning" message is indicating an isolation problem (likely in the Drive Unit), which can start to pop up when coolant starts to get in there. If that is indeed the case, the codes will come back as more coolant continues to leak, and it will only get worse as more time goes by... If the coolant gets to the inverter portion of the drive unit, there is a very high likelihood that the inverter will be destroyed, so it is important to know if there's a problem before that happens (especially if you want to try and have the drive unit rebuilt).
It's possible the isolation warning could be another component, including the battery heater. Just because it's working doesn't mean there's nothing wrong with it... There are ways to check the isolation of each HV component individually, but it is quite involved, and I would recommend having knowledge of working on HV components before embarking on such an endeavor. For "extensive" testing, some components (including the rear drive unit/subframe assy.) may need to be removed from the car.
