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

[JimInWI]

My 75D is now limiting to 24A as well. Tried a few different L2 chargers and all have the same result. Started about a week ago when we the temps were pretty hot, so wondering if that had anything to do with it. Surprisingly no errors. Planning to do the swap.

Mine is an XS2-1. I'm seeing some XS3-1 units on ebay. Has anyone successfully swapped for one of these?

 

[john pane]

Tesla gave me the old charger when they replaced mine (2017 75D). It's not clear this is useful to anyone, but if it is please let me know.

 

[dbldwn02]

My 75D is now limiting to 24A as well. Tried a few different L2 chargers and all have the same result. Started about a week ago when we the temps were pretty hot, so wondering if that had anything to do with it. Surprisingly no errors. Planning to do the swap.

Mine is an XS2-1. I'm seeing some XS3-1 units on ebay. Has anyone successfully swapped for one of these?

Someone here got a 2-1 to work in place of a 1-1. My original post stated it wouldn't work but it looks like maybe I just got a bad unit.

I think it's safe to try. Just make sure you stage the firmware update before you do the swap.

 

[brian_paonia]

The is a full DIY on all models how to replace the onboard charger on tesla service website. You need to create and account and there you can find a complete how to.

Can you post a link to this? Does it require purchasing a subscription? Thx

 

[brian_paonia]

Hi, thanks so much for this forum and this post - so much good info.

2017 MS 75D 105K miles. Been seeing decreased charging for several months now at L2 chargers. Supercharging fine. SC remote diagnosed onboard charger, so I bought on on eBay for ~$400. Part numbers all match - says it came off a similar generation MX.

Using this post and the MS service manual, I swapped the chargers yesterday and successfully ran the software update. Errors cleared until I started charging and then same symptoms appear. 40amp Wall connector starts charging and the quickly throws CHG_u012_PilotCurrentReduced error and changes to 24/30 A.

I suppose it is possible that I bought a used charger with the same degraded state of my own. The seller is OOO for Labor Day weekend. Curious if anyone on here has any theories worth chasing. Seems like potentially the charge port/wiring could be at fault, by wouldn't I see issues with supercharging too?

Appreciate any thoughts anyone can offer - thanks!

 

[dbldwn02]

Hi, thanks so much for this forum and this post - so much good info.

2017 MS 75D 105K miles. Been seeing decreased charging for several months now at L2 chargers. Supercharging fine. SC remote diagnosed onboard charger, so I bought on on eBay for ~$400. Part numbers all match - says it came off a similar generation MX.

Using this post and the MS service manual, I swapped the chargers yesterday and successfully ran the software update. Errors cleared until I started charging and then same symptoms appear. 40amp Wall connector starts charging and the quickly throws CHG_u012_PilotCurrentReduced error and changes to 24/30 A.

I suppose it is possible that I bought a used charger with the same degraded state of my own. The seller is OOO for Labor Day weekend. Curious if anyone on here has any theories worth chasing. Seems like potentially the charge port/wiring could be at fault, by wouldn't I see issues with supercharging too?

Appreciate any thoughts anyone can offer - thanks!

I would say charging port but Tesla diagnostic says onboard charger. It's hard to say what it is without a little more info. Do me a favor and plug it in, and figure out how low the voltage is dropping. It could be a bad connection somewhere in the circuit. Teslas throttle current when they detect excessive voltage drops.

Also, try a different Level 2 plug outside of your house and see if the "new" charger is throwing the same codes as before.

EDIT 1: Thinking about it a little more...Did your original bad charger go past 24 at all or did it stop there? Could help narrow it down.
EDIT 2: And you're probably correct about the charging port being fine. Our cars super charge at 60-120kw at 400V which is between 100-250 amps. The onboard charger is only 48amps of 240V.

 

[Jose Garcia 54]

Using this post and the MX service manual, I swapped the an eBay onboard charger with my original charger on my 2017 Tesla X.

The update did not succeed. And my 12V battery died since the HV system was disabled during the failed update, preventing the 12V battery from charging.

I had Tesla mobile service come and they explained that the charger I put in might not be compatible due to a VIN blacklist on the ebay charger or Tesla changes their firmware to prevent onboard chargers from being swapped. They say an error "onboard charger MIA" was showing when they tried to update my car via CAN.

Looks like i will have to tow my X to service and pay for a new charger. Hopefully they discount the labor since the car is already opened up.

 

[dbldwn02]

Using this post and the MX service manual, I swapped the an eBay onboard charger with my original charger on my 2017 Tesla X.

The update did not succeed. And my 12V battery died since the HV system was disabled during the failed update, preventing the 12V battery from charging.

I had Tesla mobile service come and they explained that the charger I put in might not be compatible due to a VIN blacklist on the ebay charger or Tesla changes their firmware to prevent onboard chargers from being swapped. They say an error "onboard charger MIA" was showing when they tried to update my car via CAN.

Looks like i will have to tow my X to service and pay for a new charger. Hopefully they discount the labor since the car is already opened up.

Man, I'm sorry to hear that. I really hate when we're not "allowed" to work on our own cars. It's a two hour job. If they sold remanufactured chargers for $1000 it wouldn't be so bad, but $3000 for something that goes out after 4-6 years is way too expensive.

What was wrong with your original charger? Was it the same problem some people have had?...Half rate charging? 24amps...

If your old charger still works-ish, put it back in and keep using it.

 

[Jose Garcia 54]

Man, I'm sorry to hear that. I really hate when we're not "allowed" to work on our own cars. It's a two hour job. If they sold remanufactured chargers for $1000 it wouldn't be so bad, but $3000 for something that goes out after 4-6 years is way too expensive.

What was wrong with your original charger? Was it the same problem some people have had?...Half rate charging? 24amps...

If your old charger still works-ish, put it back in and keep using it.

Thanks. It was a good learning experience at least. Car could charge but not supercharge. I have free supercharging and drive a lot so it is important for me to be able to supercharge.

Since my 12V is dead, I think it is easier to just take the car to Tesla now. The mobile tech left without selling me a new charger. Even if I had a new 12V I would need to get a battery maintainer.

 

[dbldwn02]

Thanks. It was a good learning experience at least. Car could charge but not supercharge. I have free supercharging and drive a lot so it is important for me to be able to supercharge.

Since my 12V is dead, I think it is easier to just take the car to Tesla now. The mobile tech left without selling me a new charger. Even if I had a new 12V I would need to get a battery maintainer.

Ahhh...ok, that makes sense now. This thread is more for a faulty AC to DC onboard charger. Supercharging issues are a whole nother beast.

Your onboard charger runs in bypass mode during supercharging. The DC goes in and goes right out, bypassing nearly all the electronics in there. If the supercharger bypass relay isn't clicking over to DC supercharging, there can be several other things that are wrong with your car.

The HV relay in the charger could be bad...but it's not something you hear of frequently
Your car could also be inadvertently blocked from the supercharging network, hence the "blacklist VIN" comment from the tech.

What errors do you get when you try to Supercharge?

Also, your 12V battery isn't bad, it's just dead. A 6 amp charger was enough to bring mine back to life and keep the car on for the duration of the software update.

 

[Zeemo]

Using this post and the MX service manual, I swapped the an eBay onboard charger with my original charger on my 2017 Tesla X.

The update did not succeed. And my 12V battery died since the HV system was disabled during the failed update, preventing the 12V battery from charging.

I had Tesla mobile service come and they explained that the charger I put in might not be compatible due to a VIN blacklist on the ebay charger or Tesla changes their firmware to prevent onboard chargers from being swapped. They say an error "onboard charger MIA" was showing when they tried to update my car via CAN.

Looks like i will have to tow my X to service and pay for a new charger. Hopefully they discount the labor since the car is already opened up.

When you did this you need to connect your 12V battery to a power supply preferably set at approximately 14V which will allow for 20 or Amps (thats what I used). or have another car with jump leads connected.

 

[dbldwn02]

When you did this you need to connect your 12V battery to a power supply preferably set at approximately 14V which will allow for 20 or Amps (thats what I used). or have another car with jump leads connected.

Unfortunately, most U.S. chargers don't let you pick the voltage, only the amps. My car charger only does 6amps which was enough to get the software update done. I started with a fully charged 12V battery too.

The 2nd car battery is a good idea, too.

 

[JimInWI]

I attempted a swap this weekend with a used charger from eBay. The one I received looked like the case had been opened, which made me a little suspicious so I went ahead and opened it up. I saw evidence that one of the power boards had already failed (burn marks on one component). There are 2 40A fuses on each board so I decided to check them. Sure enough, they were blown. Fuses on the other board checked out okay.

Decided to open mine up to investigate since I already had it out. No evidence of a failed component but both of the fuses were indeed blown on one board. For fun, I swapped the fuses from the good board on the ebay unit into mine and reinstalled. Tried charging and both fuses popped again. Pretty sure I heard it happen. So that confirms a bad board in mine, and the reason I'm limited to 24A.

Just an FYI for anyone who would want to check theirs. I did find replacements on DigiKey, but I wouldn't recommend just swapping them like on the Gen2 chargers. If they are blown, it's probably for a reason.
https://www.digikey.com/en/products/detail/littelfuse-inc/0HEV040-ZXBD/5233893

 

[dbldwn02]

I attempted a swap this weekend with a used charger from eBay. The one I received looked like the case had been opened, which made me a little suspicious so I went ahead and opened it up. I saw evidence that one of the power boards had already failed (burn marks on one component). There are 2 40A fuses on each board so I decided to check them. Sure enough, they were blown. Fuses on the other board checked out okay.

Decided to open mine up to investigate since I already had it out. No evidence of a failed component but both of the fuses were indeed blown on one board. For fun, I swapped the fuses from the good board on the ebay unit into mine and reinstalled. Tried charging and both fuses popped again. Pretty sure I heard it happen. So that confirms a bad board in mine, and the reason I'm limited to 24A.

Just an FYI for anyone who would want to check theirs. I did find replacements on DigiKey, but I wouldn't recommend just swapping them like on the Gen2 chargers. If they are blown, it's probably for a reason.
https://www.digikey.com/en/products/detail/littelfuse-inc/0HEV040-ZXBD/5233893

Good info! Doesn't look like you can replace those banks either...kinda hardwired to the backplane on the right? Was hoping if my "new" one goes half out again, I still have my old one with a good bank in it.

In my line of work (generator/HVAC mechanic) I'll usually replace fuses one time and if they pop right away, then yea, there's definitely a good reason they're popping.

 

[brian_paonia]

I would say charging port but Tesla diagnostic says onboard charger. It's hard to say what it is without a little more info. Do me a favor and plug it in, and figure out how low the voltage is dropping. It could be a bad connection somewhere in the circuit. Teslas throttle current when they detect excessive voltage drops.

Also, try a different Level 2 plug outside of your house and see if the "new" charger is throwing the same codes as before.

EDIT 1: Thinking about it a little more...Did your original bad charger go past 24 at all or did it stop there? Could help narrow it down.
EDIT 2: And you're probably correct about the charging port being fine. Our cars super charge at 60-120kw at 400V which is between 100-250 amps. The onboard charger is only 48amps of 240V.

Hey sorry I missed this reply - didn’t get a notification and sort of tabled the issue for now. I tried several level 2 when I first noticed the issue - same results. The charger never goes past 23 amps. Voltage steady around 243V - i haven’t seen it deviate much from this. I have there chargers at home - a new wall charger and actually 2 mobile chargers, one first gen and one second. All same symptoms and I tried at least two of them with the used ebay charger before I pulled it back out and returned it. Im leaning toward I got another bad charger from ebay. seems people are pulling these parts from salvage vehicles and either it’s hard to or choosing not to test them.
thanks for the consideration, I guess I’ll try another ebay charger.

 

[dbldwn02]

Hey sorry I missed this reply - didn’t get a notification and sort of tabled the issue for now. I tried several level 2 when I first noticed the issue - same results. The charger never goes past 23 amps. Voltage steady around 243V - i haven’t seen it deviate much from this. I have there chargers at home - a new wall charger and actually 2 mobile chargers, one first gen and one second. All same symptoms and I tried at least two of them with the used ebay charger before I pulled it back out and returned it. Im leaning toward I got another bad charger from ebay. seems people are pulling these parts from salvage vehicles and either it’s hard to or choosing not to test them.
thanks for the consideration, I guess I’ll try another ebay charger.

Yea, that's unfortunate. It definitely sounds like a failed AC/DC bank in the on-board charger still.

There's two AC/DC banks in our chargers and they seem very fragile for the function they perform. I guess we can be grateful that it's only 50% speed reduction versus a complete failure. Per previous posts, it sounds like there's replaceable fuses on the boards, however it seems they just immediately pop if you replace them. Indicative of an actual problem and not a nuisance trip.

I wish Tesla would sell remanufactured or new units directly to users. I'm not sure how much of the $2800 is labor and how much for the actual charger. I saw some brand new in plastic chargers selling for $800-1000 on ebay, several months ago.

 

[JimInWI]

Good info! Doesn't look like you can replace those banks either...kinda hardwired to the backplane on the right? Was hoping if my "new" one goes half out again, I still have my old one with a good bank in it.

In my line of work (generator/HVAC mechanic) I'll usually replace fuses one time and if they pop right away, then yea, there's definitely a good reason they're popping.

There would be a lot of ungluing and unsoldering to remove a board. I did find a video on YouTube that showed a guy actually repairing a power component on the bottom side of the board, but it he didn't even fully remove it. If the ebay seller lets me keep the bad one, I may try tearing it apart for fun.

 

[kg7jo-]

I recently successfully completed the replacement of the Gen 3 charger in my Model S 75D. However, all four fuses in the charger burnt out simultaneously, most likely due to issues with my UMC. I purchased an XS1-1 charger from eBay, and upon its arrival, I discovered that the Blue PTC plug was cracked. So I removed it, but forgot to reinstall the plug from my original charger. This led to BMS_F036_SW_HVIL error, and it wasn't until after reinstalling the system twice that I realized that was the problem. Anyway, thanks for the post, and saved me $3k so I could take my family out for a fancy dinner.

 

[dbldwn02]

I recently successfully completed the replacement of the Gen 3 charger in my Model S 75D. However, all four fuses in the charger burnt out simultaneously, most likely due to issues with my UMC. I purchased an XS1-1 charger from eBay, and upon its arrival, I discovered that the Blue PTC plug was cracked. So I removed it, but forgot to reinstall the plug from my original charger. This led to BMS_F036_SW_HVIL error, and it wasn't until after reinstalling the system twice that I realized that was the problem. Anyway, thanks for the post, and saved me $3k so I could take my family out for a fancy dinner.

Good to hear!

Thanks for posting the error code for future reference!

 

[Alluck]

cant you turn on service mode anywhere?