2023.12.1 Updated Service Menu and tools for legacy cars

[geordi]

On my 2016 MX, I pulled the fireman's loop tonight to try this in service mode. Gateway was already unlocked. BMS reset failed with the exact same error code as when the fireman's loop was connected.

The only changes were the battery graphic on that screen turned yellow (from green) when the loop was out, and I got a couple errors about low voltage to the contactors and inability to charge the 12v (B/c the loop was open so yeah).... But no joy on this reset.

How the heck are you supposed to do this?

 

[H0W42D]

Wow you are brave BUT many thanks.. well I have no clue then?!

 

[geordi]

Wow you are brave BUT many thanks.. well I have no clue then?!

You're welcome I guess... It's no big deal to pull the fireman's loop though, that's what it is there for with a plug?

If you are going to work on the vehicle (like replacing the 12v battery for example) it is part of the procedure to pull that to fully power off the car. When you remove that, the low voltage power to the high voltage contactor relays is removed, and the contactors open immediately. That keeps all the HV power inside the pack, and nowhere else.

It's no big deal.

To fully power off the car, you need to also pull the negative off the 12v battery, and then it is a 3 ton yard ornament until you power it back up. Don't close the frunk at this point, or you will be sorry!

 

[brainhouston]

Gateway was already unlocked.

Side question, was gateway unlock available at certain version? how did u unlock it?

 

[geordi]

Side question, was gateway unlock available at certain version? how did u unlock it?

It provides the instructions in the service mode when you need it. To unlock the gateway, you have to be on internal power (no charging cable connected) and hold the turn signal to the right on, and press the brake pedal for 8 seconds. It will come up with a counter, and then unlock the gateway for 5800 seconds. (I don't know why it is like that, but it is).

Then it will let you do the routines.

 

[Gixx1300R]

try this, plugged in with SOC below 50% and not charging

 

[lightningltd]

try this, plugged in with SOC below 50% and not charging


View attachment 944227

The one we are talking about is the reset BMS one.

 

[Gixx1300R]

The one we are talking about is the reset BMS one.

yes, I know. the contactors need to be open. Wouldn't hurt to try

 

[geordi]

Is there another way besides pulling the fireman's loop? B/c I already did that and it didn't help.

 

[lightningltd]

Dunno. What else would kill power (open the contactors) from the drive battery but allow the electronics to be on?

 

[geordi]

That's pretty much all I know to do - but the reset BMS didn't like that.

 

[DownshiftDre]

Pulling HV contactors may seem the only way. The 12V electronics will still operate but you will be on the LV battery so probably limited on time. Thankfully this test is a few seconds max I imagine.

 

[xxaarraa]

Has anyone with a 2020+ Model S successfully accomplished BMS reset via the service menu? Seems like @geordi tried in his X by unlatching the fireman's loop but it was still a no-go. I am wondering if anyone else has had success.

 

[geordi]

I haven't had a BMS error, but I'm not sure that actually would isolate the BMS from the battery anyway. The fireman's loop SHOULD open the contactors and keep the power in the battery and anything that is directly connected (like the BMS?) but my knowledge on that is limited. I do know that when the fireman loop is open, there still is something connected to the 12v battery, b/c it still wants to spark when connecting the 12v battery directly.

The ONLY way I know to disconnect all power seems to be unplugging the 12v battery, but I don't know that would reset the BMS. I haven't had any issues there to need to try.

I do need to replace my onboard charger, and will be pulling both the fireman's loop AND the 12v battery (I have installed a disconnect switch on that line so I don't need to keep removing the fragile ground screw) and then testing the contacts on the charger with a volt meter before getting near them. But I'm also probably STILL going to treat them as live, because that's smart. Always respect high voltage.

 

[hydro]

I need help regarding the BMS topic. Yesterday our suspension (EAS/ Continental) froze and blew the air compressor fuse. So had to disconnect the 12V and the fireman's loop and change that F82 40A fuse. When reconnected everything (12V was disconnected overnight to be able to find a 40A fuse locally) the 12V was dead so unable to get the car going and had to boost. The person that was with me put the negative from the boost pack on the ground nut contact and all was fine being able to drive around with no issue up to this morning when the car, after falling asleep during the night, was dead again. So asked for an appointment to change the 12V (210$ + tax CAN) and Tesla service looked at the logs and mentioned that there is a BMS power issue and ask me if I ever had the fireman's loop disconnected and used a boot pack. I said yes and we are there at this point of scheduling the appointment. What is a BMS power issue and is that costly? Thanks