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Replacing Onboard Charger Gen3 2017 MS75D...My Experience (With Photos)

Here is my experience replacing my onboard charger on my 2017 Tesla MS75D.

Disclosure…

Don’t try this at home, YMMV, High voltage, you can kill yourself if you do something stupid, yadda-yadda, I’m not liable if you do this, warranty void, blah blah blah…

My car specs:
  • 2017 MS 75D (USA)
  • Gen 3 charger
  • Part # 1052532-00-D Rev01
  • >ADC12< 113492 XS 1-1
  • XS 2-1 WILL NOT WORK IF YOU’RE REPLACING XS 1-1
  • 48amps – Single Charger
Symptoms:
  • While using Level 2 chargers, my amps would jump around from 0-24 and then settle at 24 amps
    • Tesla Mobile Connector capable of 40amps
  • Multiple errors including:
    • Unable to charge, check charging equipment
    • Unable to charge, disconnect cable and retry
    • Charge speed reduced, unplug and try again
    • Notice how it never blamed on the on-board charger???
      • This software oversight was disappointing
      • How hard would it be to just say, “Your onboard charger is half-broken”?
  • I tried charging with my wife’s 1772…no change
  • Took it to a Tesla Destination charger (48amp capability) and it did the exact same thing
  • Voltage never dropped during charging
    • IMO, this ruled out a faulty charging port, which was replaced 18 months ago.
  • Supercharging unaffected
So, I could have kept limping along at 24amps (50%) until it gave out all the way, but that doesn’t seem right to do that on a 5-year-old Tesla.

First off, these don’t have the troublesome 50-amp fuses from Gen2 chargers. That was my first mistake. After removing the back seat, I could immediately see I had a different/newer charger.

Part # Warning
I bought a charger off EBay from a project car guy. (integrityholdings) He had a stack of them and was unloading them for $300. Unfortunately it was the XS2-1 instead of XS1-1. I didn’t think anything of it and put it in. Tons of errors. I tried to redeploy firmware but it failed. I can only assume the XS2-1 is a slave from a 72amp dual charger setup. I got a hold of the seller and he was able to find an XS1-1. Restaged firmware, swapped charger, installed firmware, and all was good. Charging at a full 48amps now. No issues!

Tools Needed
  • Torx Bits (T-20 – T-30)
  • Sockets (Metric)
  • Screwdrivers
  • Multimeter for checking High-Voltage (600V rating)
  • If you don’t know how to use a multimeter for checking AC/DC voltages, you probably should stop here.
  • Electrical gloves
  • Wife to hold up coolant lines so they don’t spill everywhere
Part 1 - Pre-Setup and Software Staging – Your car won’t be driveable if you don’t accomplish these procedures first!

1. It’s almost guaranteed you’ll need to flash the firmware on the new charger after you install, so you’ll need to have a software update pending before you start the replacement
2. Go to a Tesla Service center or approved body shop (most body shops work but not all)
3. Push and hold on your Model in the Software Screen, let go after 5 seconds
PXL_20220216_200109414.jpg


4. Enter “service”
PXL_20220216_200121801.jpg


5. Remove speed limit
PXL_20220216_200129924.MP.jpg


6. Back out of menu
7. Pick “Software Reinstall”
PXL_20220216_200022515.jpg


8. Pick “Full Reinstall”
- Partial Install probably works, but why chance it?
9. MCU will eventually show a software update is available.
- Could take up to an hour
- Do NOT install yet!
- Leave car in “Service Mode” just in case
10. Drive home
11. Ensure software update is ready to be installed before proceeding

Part 2 – Replacing Charger

1. Move driver and passenger seat all the way forward
2. Roll down windows and open all doors
3. Take pictures along the way, to help with re-assembly
4. Remove frunk…
-
PXL_20220217_022559201.MP.jpg


5. Disconnect 12V battery (negative terminal only) and fireman’s loop


PXL_20220113_043317703.jpg



6. Charger is located under rear bench seat
7. Pull up on the front part of the seat. There are two retaining clips that you’ll probably break in doing this. The only way to get it out without breaking them is to use a flat head screwdriver. I couldn’t get it, so I just pulled up hard on the seat. I’ll order more later.
8. Disconnect seat weight sensor connectors…3 of them

PXL_20220108_174456867.jpg


9. Remove side seat small pieces by pulling at the top, toward the front of the car. They should pop out.
10. Remove seat backs starting with the larger one. There’s a rod that connects them at the hinge point. You have to pull the seat toward the door to get it out.

PXL_20220108_174646185.MP.jpg


11. Remove 8 bolts to release the cage. (Large Blue "Remove" is the seat trim piece that comes off in step 9.

PXL_20220108_175222780.MP.jpg


12. Cage has one cable running to the frame of the car. Disconnect before removing cage
13. Remove cage to access the charger
14. Pull Blue PTC plug from charger
15. Red clip needs to be pulled to unlock it
16. Put on electrical gloves
17. Open small lid of charger to access 4 HV terminals (T-20 Torx screws)
18. Check terminals against chassis ground for voltage (AC AND DC).
- If more than a couple volts are present, STOP and make sure you disconnected 12V battery and don’t have your car hooked up to a charger.
PXL_20220108_184853328.jpg


19. Disconnect ground cables (2 of them) from charger (1 is Torx, 1 is a metric bolt)
20. Disconnect:
- 4 orange HV cables
- Nuts on input cables
- Torx on output cables
- The black retaining clips are a pain to release…use flat head screwdriver
21. Disconnect communication cable from far side of charger
- Red clip needs to be pulled to unlock it
22. Remove two bolts and two studs holding charger in place
23. Place towels under coolant lines
24. Get someone to hold coolant lines up
25. Disconnect coolant lines using pliers to release clamps
26. Plug coolant ports on charger if you have plugs, otherwise be prepared to make a mess
27. Remove charger and install new charger
28. Install coolant lines
29. Release Wife or Husband to go back inside
30. Reinstall ground cables, HV cables, comm cable, PTC Blue plug, etc…
31. Reinstall cage, rear seat, seat sensor cables, etc…
32. Connect Fireman's Loop and 12V battery
33. Errors will mostly likely pop up
34. Start firmware update
36. Cross fingers and get a drink (this will take a while)
37. Reinstall whatever left over pieces you have.

If all went well, congrats on saving $2500+
 
That was a great post, you should add it to www.fixyourtesla.com, or wherever the future wiki for fixing all Tesla issues ends up

Wha'dja do with the old charger?
Thanks, will do.

I put it on the shelf for now. I found a tear down video showing how to use it as in an ICE to electric conversion conversion but not how to repair it. The components are dense in the case.
When I have time, I'll tear into it. It half works so it can also be a fall back if the "new" one decides to completely die.

I feel for those who can't do this repair on their own. 4.5 year old car and already needing to spend $3.5k to fix it. I got lucky finding help on this forum. Got the job done for $500 and 3 days of trial and error. Learned a lot though.
 
Thanks, will do.

I put it on the shelf for now. I found a tear down video showing how to use it as in an ICE to electric conversion conversion but not how to repair it. The components are dense in the case.
When I have time, I'll tear into it. It half works so it can also be a fall back if the "new" one decides to completely die.

I feel for those who can't do this repair on their own. 4.5 year old car and already needing to spend $3.5k to fix it. I got lucky finding help on this forum. Got the job done for $500 and 3 days of trial and error. Learned a lot though.
I assume the step of going to a SC or approved body shop allows the car to enter service mode via location?

Also I’m curious if you’ve torn in to the charger, I have a 2016 X and i Can supercharge fine but my home charger and wall charger both start to work fail within a few minutes with the red ring on the charge port and error CHG_f083. I thought maybe I could replace fuses like a gen1 on board charger but it looks like you’re saying that’s not possible. I watched a couple Rich Rebuild videos and he took apart both a 48a and 72a charger and I could see the fuses in his video, did you discover there aren’t any fuses now?

Thanks in advance.
 
I assume the step of going to a SC or approved body shop allows the car to enter service mode via location?

Also I’m curious if you’ve torn in to the charger, I have a 2016 X and i Can supercharge fine but my home charger and wall charger both start to work fail within a few minutes with the red ring on the charge port and error CHG_f083. I thought maybe I could replace fuses like a gen1 on board charger but it looks like you’re saying that’s not possible. I watched a couple Rich Rebuild videos and he took apart both a 48a and 72a charger and I could see the fuses in his video, did you discover there aren’t any fuses now?

Thanks in advance.
Yes...you need to be in service mode before you swap the charger. It's the easiest way. Otherwise you're left with a brick on boot.

It's definitely your charger that's shot. Supercharging bypasses pretty much the whole onboard charger.

I didn't break into my old one yet but I watched a guy on YT break apart a gen3 48amp charger. Didn't see any accessible fuses in that video. My issue definitely wasn't fuses so I didn't was time ripping it apart at the time. I probably will, in the future.

Gen2 chargers have the fuses. My gen3 doesn't have accessible fuses, if it even has any.
 
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