Diagnostic TMS70D 2015 - isolation issue

[piwhy]

Hi,

I'm currently considering purchasing a Model S 70D with a faulty battery and 180k km.

Firstly, I want to precise that I have extensive experience in electric vehicle maintenance and battery repair. I've worked on dismantling full batteries from vehicles like the Opel Ampera alias Chevy Volt, rebuilt custom battery packs for French PSA EVs, and worked on various other EVs using Tesla modules or others battery types. I'm equipped with the necessary tools, experience, and qualifications to work on high-voltage (HV) systems.

While I'm confident in my skills, I'm relatively new to Tesla vehicles and am seeking information to diagnose this car as accurately as possible before making a purchase.

The primary issue appears to be an HV isolation problem, likely due to water ingress into the battery pack. The current faults displayed are: bms_f123, bms_w035, bms_w073, bms_w123, and other GTW faults.

I haven't yet obtained the BMS_isolationResistance value, but I do know that all x14 battery modules are well-balanced (16mV difference) at around 3.95V (via scanmytesla app).
Before purchasing and potentially removing the battery pack for inspection, I'd like to be around 80-90% certain about the location of the issue.
I can perform any necessary checks on the car tomorrow. I have a PEAK CAN adapter on hand and access to the vehicle CAN bus under the MCU. I perfectly know that the bms_f123 issue is significant and can't be reset without a full battery isolation check. However, if I'm correct, and if the isolationResistance measured by the BMS is above 1MOhms when contactors are open, it might be worth resetting the error to determine whether the isolation issue truly originates from the battery pack or from another HV device like the heater.

I'd greatly appreciate any tips or guidance to diagnose this car correctly.

Thank you.

 

[brainhouston]

f123 is def coming from inside the pack, bms checks this with contactors open so it knows the difference
u can reset it (i did it) for testing but it'll come back if water is still there
u 'might' need to reset it after its fixed (i didn't have to, cleared on its own)
i think newer packs/firmware might clear on its own but older needs reset, from what i experienced/read...

have a look here at my story:

Car died. BMS errors f123, w123, w073, w035, w142, w158

Unfortunately my 2016 MX 90D decided to surprise me with these errors :confused: We had a few days of cold/snow days and the car did fine. Last couple of days its been above freezing and everything already melted. I drove the car in the morning, then parked on driveway. Few hours later, started...

teslamotorsclub.com

 

[piwhy]

f123 is def coming from inside the pack, bms checks this with contactors open so it knows the difference
u can reset it (i did it) for testing but it'll come back if water is still there
u 'might' need to reset it after its fixed (i didn't have to, cleared on its own)
i think newer packs/firmware might clear on its own but older needs reset, from what i experienced/read...

have a look here at my story:

Car died. BMS errors f123, w123, w073, w035, w142, w158

Unfortunately my 2016 MX 90D decided to surprise me with these errors :confused: We had a few days of cold/snow days and the car did fine. Last couple of days its been above freezing and everything already melted. I drove the car in the morning, then parked on driveway. Few hours later, started...

teslamotorsclub.com

Yes I read your story yesterday, it could be similar indeed.
I know defaut will come back if there is water inside.
So you confirm that CAN frame sequence used to reset this defaut for testing is the "Clear stress" can frame (04 31 01 04 06 00 00 00) right ?
Thanks

 

[brainhouston]

So you confirm that CAN frame sequence used to reset this default for testing is the "Clear stress" can frame (04 31 01 04 06 00 00 00) right ?
Thanks

no, i haven't tried it myself, even tho i bought a CAN adapter to send commands (was gonna use it after fix but didn't need to)
i just paid LayZ to reset it remotely for me ( i was in a bit of rush to get it fixed)
but if u try it, let me know, i'm curious if it works
alternatively u can buy 1 day toolbox access n reset it

 

[piwhy]

I had the opportunity to check more deeply today on the car.
Indeed cell balancing is not critical, around 15/16mV.
I have a trace file of the powertrain CANBUS, I'm not sure about CAN database informations I found, isolation value is on id 0x212 ? so around 112kOhms (hex value "70" in the screenshot below) at the moment ?
I didn't try to reset the bms_f123 error I only tried a bms reset through the service mode interface ; immediately after this reset the three active alerts were : BMS_f123, BMS_w123 and BMS_w142 ; so the defaut seems to be clearly located in the battery pack

 

[brainhouston]

nobody really knows what that BMS reset does but cool that u got to try it
my MCU is rooted so i have access to diag screen which shows me isolation but i don't know what CAN id it is...
in my case when car was leveled water didn't touch anything so isolation went back up to ~3MOhms so it reset fine but when the car tilted errors came back
maybe that BMS reset button will work if ur iso is high again but i'm not sure...

 

[piwhy]

nobody really knows what that BMS reset does but cool that u got to try it
my MCU is rooted so i have access to diag screen which shows me isolation but i don't know what CAN id it is...
in my case when car was leveled water didn't touch anything so isolation went back up to ~3MOhms so it reset fine but when the car tilted errors came back
maybe that BMS reset button will work if ur iso is high again but i'm not sure...

Ok, that's why I was not able to find isolation value and detailed informations on the MCU . I didn't have root option in mind...
Is there someone able to give me the CAN id where I can find the isolation value ?
Thanks !

 

[piwhy]

So, I finally bought this car.
BMS_f123 -/ BMS_w123 errors is (one more time) clearly a water ingress issue in the battery pack.
I started to open the battery pack, I will remove and check all the modules before to decide if I repair+reseal this pack of if I sell the modules to buy a complete battery pack (ideally a 90kwh version).

I'm still interested if someone has informations about isolation value broadcasted on the CANBUS or if someone has informations about the "Battery Shipping Tool" application ? I have everything needed to make a MX150 extension harness between the car and the pack or to make a simplified harness with 12V and canbus to get informations directly from the BMS.

I will keep you informed about the global pack diagnostic.

 

[piwhy]

I managed to get the isolation value of the standalone battery pack before to open the main lid. Unfortunately I don'y have any point of comparison as I never get this value before to open the fuse lid and the front cover of the battery pack.
But at this point the isolation provided by the bms seems to be pretty good (3300kOhms).
So I reconnected the battery pack on the side of the vehicle (hopefully the LV mx150 connectors are exactly the same than on the chevy volt battery and I already made extension harness in the past for a similar operation). But the BMS_F123 error is still active.
So, this error is latched somewhere or the fault is located just after the main contactors ? (I tried without connecting the HV lines to the car, same error)

I know that the best option is to open he whole battery pack when humidity was inside, but I also know that the car was driveable two/three weeks ago, so I keep in mind that there is a chance that water ingress was for the moment located around the fuse box (5mm of water at the bottom of the orange box) and hopefully not elsewhere. I just don't want to open the main lid for the fun if the issue is not there...

 

[brainhouston]

what software is that? from Tesla or 3rd party?
did u figure out if CAN id was correct for isolation?

from what i read, i think on older packs like urs you'll need to reset f123
on my newer pack, with fuse at the bottom, the error went away after i dried it
keep in mind, inside the pack, BMS is always connected to HV so maybe it uses some of that power to keep the logs, not sure
i disconnected mine so maybe thats why it reset itself... but i did reset the err with pack installed for testing n it did reset, then came back soon after

if water got to fuse box it got to the whole pack, u can see it in ur pic
someone in other thread suggested using shoe dryer to run air thru vents (u can buy those from tesla) to dry the pack
that would be the only option without opening main lid
tilt the pack forward n leave it for a while to see if more water will seep to the front...

 

[piwhy]

what software is that? from Tesla or 3rd party?
did u figure out if CAN id was correct for isolation?

from what i read, i think on older packs like urs you'll need to reset f123
on my newer pack, with fuse at the bottom, the error went away after i dried it
keep in mind, inside the pack, BMS is always connected to HV so maybe it uses some of that power to keep the logs, not sure
i disconnected mine so maybe thats why it reset itself... but i did reset the err with pack installed for testing n it did reset, then came back soon after

if water got to fuse box it got to the whole pack, u can see it in ur pic
someone in other thread suggested using shoe dryer to run air thru vents (u can buy those from tesla) to dry the pack
that would be the only option without opening main lid
tilt the pack forward n leave it for a while to see if more water will seep to the front...

Yes that's the official Tesla tool (available online on tesla service) that allow to connect directly on the battery pack on the X036 connector, the grey one (Molex MX150 connector reference : 33472-1202)
Wiring of the X306 connector is as follow : CAN-H : pin10 ; CAN-L : pin9 ; +12V : pin2 ; GND : pin8/12 - nota a 120 Ohms resistor must be added between CAN H and CAN L
This kind of CAN adpater can be used : PCAN-USB: PEAK-System
I will tilt the pack to verify there is no more water on the front. Then I will find the correct procedure and if needed on this pack generation try a reset...

 

[brainhouston]

Yes that's the official Tesla tool (available online on tesla service) that allow to connect directly on the battery pack on the X036 connector, the grey one (Molex MX150 connector reference : 33472-1202)
Wiring of the X306 connector is as follow : CAN-H : pin10 ; CAN-L : pin9 ; +12V : pin2 ; GND : pin8/12 - nota a 120 Ohms resistor must be added between CAN H and CAN L
This kind of CAN adpater can be used : PCAN-USB: PEAK-System
I will tilt the pack to verify there is no more water on the front. Then I will find the correct procedure and if needed on this pack generation try a reset...

Nice thanks for informative post
Did u need Toolbox subscription to use that tool?

 

[piwhy]

Nice thanks for informative post
Did u need Toolbox subscription to use that tool?

Yes you can download it when you have access to the online toolbox. (I got it now if you need it) I paid 1h access to reset the isolation error on the bms.

So I confirm, (on a 2015 70D Model S with MCU2) in case of BMS_F123 and/or BMS_W123 there is a real serious internal problem that must be solved correctly, but when the problem is identified and corrected this error is latched and must be reseted via online Toolbox !

For the moment the pack is still open (front box only), connected on the side of the vehicle, the isolation value when contactors are open is at 3365kOhms today. The pack is ~5° tilted to be sure there is no water in the central bay. I will take the opportunity to check the valves at the same time. I'm also considering to heat up the pack while is open during few days to be sure to remove potential remaining humidity...

Is there any other useful check or improvment that can be made while the pack is on the table ?

 

[brainhouston]

u probably should replace that sand fuse to current powered one
it will require Toolbox to update fuse type

 

[piwhy]

u probably should replace that sand fuse to current powered one
it will require Toolbox to update fuse type

Pyrofuse on a 240kW 70D is really recommended ? It makes sense on a performance model or with ludicrous option but I can't imagine it can blow on this model ?
I don't really like the idea to mount a second hand pyrofuse that won't be easily accesible on this battery model...

 

[brainhouston]

Pyrofuse on a 240kW 70D is really recommended ? It makes sense on a performance model or with ludicrous option but I can't imagine it can blow on this model ?
I don't really like the idea to mount a second hand pyrofuse that won't be easily accesible on this battery model...

Its official Tesla superseded part

Battery Fuse Replacement 2016 Model S 90D

Driving my car today a little error popped up and said : “Battery Fuse Needs Replacement - Schedule Service” Anybody know what that entails / costs? -Zach

teslamotorsclub.com

Pyro Fuse Fuss

Have seen multiple Model S reports, both in USA and Europe, over the past few days indicating alert that battery operated pyro fuse needs replacement with newer self powered pyro fuse. In some cases pack needs removal due to location of access cover. So far underdetermined if covered under...

teslamotorsclub.com