Cybertruck "engineering study" for seatbelt sliding mechanism service

[elmore]

Just created a service appointment for a seatbelt sliding mechanism fix, and automatically it added a service bullet point of:
Cybertruck Ancillary HV Harness Replacment - Engineering study

I wonder what that is about!

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[JER]

Got the same thing yesterday, I put in a ticket for rattle by drivers side seat belt area and it added the harness replacement.

 

[RDMSguy]

I also noticed that was added on to my service ticket for next week. Founders/VIN 37xxx.

Edit: Should mention that I am not going to the service center for anything seat belt related.

 

[TeslaKen]

I have a rattle, particularly at low speeds from the driver side seat belt upper attachment area and have a service appointment for it this Tuesday, I will point this out to the service advisor.

 

[JER]

If you don't mind passing on what they find for your rattle, and what they say about the harness. Thanks

 

[sybertruck]

Just created a service appointment for a seatbelt sliding mechanism fix, and automatically it added a service bullet point of:
Cybertruck Ancillary HV Harness Replacment - Engineering study

I wonder what that is about!

I received the same thing from when I got a flat tire and had the truck towed to the service center. Unfortunately I did not bring my spare or tire plug kit(learned the hard way). Prior to the flat tire I had multiple error messages about all of my driver assistance features like brake regen, vehicle hold, blind spot monitoring, traffic aware cruise, and many more errors. This was completed unrelated to my flat that occurred 30 minutes later. The HV Harness study is not related to the other service items like the OP seat belt or my flat tire. It is just that they detected this issue.

I was able to drive the truck with these errors but it felt like a tank due to all of those things being disabled. This is the 2nd time that this occurred in the last 30 days. Prior to this the truck was in for this issue. After a reset and a good sleep, the vehicle fixed itself and all error codes were resolved. Tesla service center said they did not see any error messages.

With this being the 2nd occurrence, I did some research and it looks like the High Voltage Ancillary Harness “Engineering Study” is Tesla sniffing out an issue that they are aware of based upon telemetry they are getting from the vehicle. From what I understand, this harness connectors multiple 48v modules and when it glitches or fails, it connects to all of those modules that we’re giving me errors. Additionally it throws a “soft code” that disappears if the module resolves it itself. As a result it does not show in the Tesla logs on the level the SC is using. It’s possible that my soft reset cleared the log codes too. If I knew better and was not trying to resolve the issue maybe I should not when tried it. However when you get all these errors it’s hard to resist.

Tesla should be storing soft codes, but they may be missing them due to intermittent behavior, subsystem logging limitations, or power resets. Since they have decided to replace the HV Ancillary harness, it suggests they did detect some anomaly, even if they are not seeing stored faults.

It is possible that Tesla remotely flagged the issue based on telemetry (explaining why they decided to replace the harness) but Service Center tools are not detecting it locally because the failure is sporadic and self resolving.

it is likely related to a group of VINs and mine is early build *******4000’s. I asked SC about this and they said it was the first they have seen this. I see in the app that the HV Harness it being ordered and on its way. Truck should be done Tuesday if all goes smoothly.

That’s the extend of what I know and am suspecting right now. I hope this helps and would love to hear other’s experience with this.

i believe this is the service procedure link for it. Looks like they have to remove the truck bed cover to access it:

https://service.tesla.com/docs/Cybertruck/ServiceManual/en-us/GUID-BB2A9ECD-A09F-4E25-A56D-142B952F3E7F.html#:~:text=screws, T25, 5 Nm Clean all debris from ancillary cover Note During removal of ancillary cover any

 

[JER]

I have a rattle, particularly at low speeds from the driver side seat belt upper attachment area and have a service appointment for it this Tuesday, I will point this out to the service advisor.

I was just curious if anything came out of that seatbelt rattle that I have the same sound coming from my truck

 

[TeslaKen]

I was just curious if anything came out of that seatbelt rattle that I have the same sound coming from my truck

Supposedly fixed at service, I am monitoring.

 

[Deleted member 22486]

Just created a service appointment for a seatbelt sliding mechanism fix, and automatically it added a service bullet point of:
Cybertruck Ancillary HV Harness Replacment - Engineering study

I wonder what that is about!

I had the same item added to my next service. The best explanation I found was this:

“A Cybertruck Ancillary HV Harness Replacement involves the removal and installation of high-voltage components within the ancillary assembly of the vehicle. This engineering study focuses on procedures for safely handling and replacing critical HV harnesses, ensuring proper alignment, electrical connectivity, and insulation.”

 

[sybertruck]

When mine was in for a flat tire they did have the HV Harness on the ticket, but they had to order the part so next Thursday I will take it in just for that. I hope it gets rid of all the rogue error messages I get about once a month that disappear off the Tesla diagnostic log. Then can't see that they even occur since it fixes itself after a reboot or deep sleep.

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