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Depending on what components you already have, you may want to upgrade the pyro fuse and/or the contactors. In the most general terms, if the contactors are black (not white), they are the current version and if you haven't had any contactor related issues, you should just leave them. If you are replacing your contactors, it is obviously MUCH safer to do with the modules out of the pack so now is the time!
If the pyrofuse is the old sand/wire fuse, you probably want to replace it and if it is the kind with the onboard batteries powering it, they are only rated for 8 years and you want to get rid of that, especially if your fuse cover is top-mounted.
Fuse
Fuse
Tesla battery packs use a pyro fuse now that blows in a collision or (like any fuse) when the rated current is exceeded. The fuse part numbers you want are listed here. Many of the early packs have the original sand and wire fuse that is just a 'fuse' without the 'pyro' function. After the sand/wire fuse as discontinued, the next generation they installed had onboard batteries that were only rated for 8 years so in mid 2023, timer based warnings started showing up on owner's screens telling them to replace the fuse. This was a huge mess for Tesla because some of the packs were under warranty - oops!
In short, you don't want the fuse with the onboard battery. You want the newest version that draws a small bit of power from the HV bus passing through it. If you do change the fuse, you need to code it in Toolbox. Interesting, the sand fuse isn't listed as an option in Toolbox now, so some cars that got the 'replace fuse' error and had it clear automatically had their setting changed to the current fuse somehow. As noted, Tesla will NOT sell an end-user a new fuse so you will need to get a used one on eBay or ask a favor of a trusted vendor.
Contactors
Contactors
Here is Tesla's information about the contactors. I was told the metric was really simple. If they are white, they should be replaced. If they are black and haven't thrown an error code, leave them - they are the current ones. They are located at the back of the pack near the HV Rapidmate. Please be reminded that working near the contactors is very dangerous - especially when the pyrofuse is in. The contactors are basically big switches that turn on and off, but there is constant connection the battery + and battery - so if the fuse was in and your touched both the + and - terminals at the same time, that would be the end of you. :( If you are doing module repairs and also plan to change out the contactors, you want to do the contactors when all of the modules are out of the pack so it is 100% safe.
The other side of this area holds the BMS and the low voltage/control rapidmates. BMS failures are relatively rare so this website doesn't have any real information to share.
You will notice the BMS/rapidmate cover can be left in place if you are just removing the lid and working on modules. The fasteners that connect the lid to the rapidmate cover will come out, but the fasteners around the back of the pack shell itself can stay in place. In the photo to the right, the screws around the back have been removed but in hindsight, they didn't need to be.
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