How to remove trunk trim to access the ECU?

[minnesnowta]

Apologies if this has been answered before, but I couldn't find any relevant threads. I am looking to either peel back or remove the rear/trunk trim on the driver's side so that I can potentially swap out the ECU.

Inspired by this thread, it seems like the ECU is relatively easy to access on a Model 3, but I have yet to find any guide on how to get to it on a Y. The closest I can find are videos about how to swap out the tail lights, but those videos only peel back the trim enough to stick a wrench in to loosen the bolts that hold the lights on, not remove the panel (or at least peel it back) enough to easily access the ECU.

My Sept 2021 MYP has the cut-down ECU without CCS support. It appears that the proper ECU with CCS support is available from Tesla for $150ish and it should be a drop-in swap (though, would have to reflash the firmware, which should be possible in service mode, or wait until the next software update is available).

Has anyone else done this on their summer 2021 Y's that came without CCS support? I realize I'm jumping the gun since the official adapter isn't for sale in the US yet, but it would be nice to have it enabled for when it does go on sale.

 

[Fourdoor]

Are you talking about the charge controller board?

Keith

 

[Darmie]

Are you talking about the charge controller board?

Keith

Well, they did call it an ECU.

I did read most of that thread and I'm not sure if he ever got all his concerns corrected.

 

[minnesnowta]

Are you talking about the charge controller board?

Keith

Possibly? The part is described as "CP ECU, ASSY, GEN 4, NA", part number 1537264-00-B. Supposedly, I have a trimmed-down version of this part, part number 1537264-80-B, which lacks the CCS hardware. It should be a drop-in replacement from what I have read.

Well, they did call it an ECU.

I did read most of that thread and I'm not sure if he ever got all his concerns corrected.

He has a more difficult situation in that he has an older 3 with more changes required to get CCS to work. The summer 2021 Y's should be able to swap out the "stripped" ECU with the full featured one. At least, that is what I gather from that linked thread.

I'm surprised there's no tutorial/video out there yet for removing the driver's side trunk trim pieces and I'm afraid of snapping something doing it without a guide.

 

[minnesnowta]

Well, two steps forward and one semi-step back. I looked at the trim piece in the Tesla parts catalog to see where the clips are and determined I just had to pull it out. In order for it to come free, I had to remove these pieces:

• The plastic trim piece surrounding the trunk latch (only clips holding it in, also have to peel back rubber molding to free it).
• The driver's side "side support" (the part where the trunk lids rest on - only clips so pulls right up)
• The driver's side trunk pocket liner (has a pin in the middle that you have to pop up with a screwdriver)

Once those are out, you should be able to remove the side trim piece. Once you free the first few clips, you'll need to unplug the connectors for the 12v power port and the seat folding buttons. There is also a clip with the center-pin you need to pull up at the bottom. I was then able to wiggle the whole piece out and reach the ECU. Confirmed I have the stripped-down version (P1537264-80-B), so hopefully it's just a drop-in replacement with the full version.

Since this was just a "dry run", I didn't actually switch out the ECU as I don't have the replacement yet. My trouble with this is when putting the side trim piece back on. You can see on the diagram (part #4) that there are clips along the bottom of the panel near the rear seats. I can't figure out how to get them on cleanly and I am bending the straight plastic "prong" trying to put it back on. I think I need to remove the rear seat to get more clearance to put the piece back on correctly.

I had to reassemble everything the best I could as my wife is about to go out in the car, but I'll muck with it some more when she's back.

 

[minnesnowta]

Wife took our other car for her errands, so I was able to quickly get back to it. Disassembled the same way, but this time I guided the plastic pin (see pic) into the right spot first, then everything clipped back together perfectly!

 

[smatthew]

Just a note - its not "THE ECU" it's just "an ECU" or "Charge Port ECU"
The car has many small brains in it.

 

[EVer Hopeful]

this time I guided the plastic pin (see pic) into the right spot first

a technique I learned many years ago

 

[FalconFour]

Awesome post Now I know, too. Yep, your swap should be as easy as order -> get reflash (update or ask service to request a reflash) -> install -> apply update. I did get the "earlier gen" Gen4 ECU upgrade done, by means of an adapter harness I developed (with a little help, in that thread), that puts the right sensor signals in the right places to satisfy it that my Gen3 charge port is really a Gen4. It totally works, Supercharging at 250kW and all, and I'm fairly comfortable calling it a solved case now. None of that applies here, though - the Y is already Gen4, it seems. Just needs an alternate version of the ECU that's not lacking the CCS/PLC brains.

However, at "install", we're still left wondering how to de-energize the car without being able to easily access the 12v battery. The theory I've seen, grounded in how it's done on the Model S, is to just disconnect the "first responder loop" and it ought to boop the whole car dead. But there's some disbelief in that... it may just leave the car running on 12v.

Anyone with a Y ever do a "full reboot" or otherwise need to shut down the whole car?

 

[minnesnowta]

However, at "install", we're still left wondering how to de-energize the car without being able to easily access the 12v battery.

From that video I posted in your thread about the Y 12 volt battery swap, it seems fairly trivial to remove the plastic cover in the frunk to access the 12v battery. I have yet to try it, but he popped it off in the video without a sweat. I'll know more next week when I finally tackle the replacement.

I assume the car remains in service mode after disconnecting the 12v and "main" battery? Otherwise, I'll have to wait for the next update to be pushed to my car and attempt the swap then.

 

[FalconFour]

I assume the car remains in service mode after disconnecting the 12v and "main" battery?

Yup. Stays through reboots until you exit via the button in the menu.

 

[minnesnowta]

My ccs-enabled ECU arrived today at my SC, so I picked it up, put my Y in service mode, drove home, swapped out the ECUs, triggered a software reinstall and now I’m CCS enabled! Thanks again, FalconFour, for your write-up on how you got it working on your 3.

Note: I didn’t power down the car at all. I just unplugged the three connectors from the old ECU and plugged them into the new one. The car beeped at me while I did it, but all is well after the software reinstall.

 

[blaferty]

would you explain how to put car in Service mode?

Also, how to trigger a software reinstall?

Thanks

 

[minnesnowta]

would you explain how to put car in Service mode?

Also, how to trigger a software reinstall?

Thanks

You'll have to figure out the riddle here: Retrofit CCS compatibility onto earlier (NA) Model 3 - DIY approach - the part at the end, "Make a left turn while standing still, as you press the button to walk through the door", is not needed.

 

[minnesnowta]

Also, how to trigger a software reinstall?

Sorry, forgot to address this and I can't edit my last post. It's a fairly obvious option in the service mode menu. You can also skip the entire service mode situation if you install the new ECU while you have a software update pending. Just hold off on installing the update until you replace the ECU.

 

[thcmas35]

I have a '21 MY built 10/2021. CCS was not enabled.
I called the Glendale, AZ store this morning and they had the 00-B ECU in stock for $140. I went down to pick it up. They said they had more ECUs but could not give a number of how many. I installed tonight.

Powered down in the menu, unplugged high voltage connection under the frunk, unplugged negative terminal on the 12v, removed plastics, installed board. I reassembled everything. At this point ccs is still not enabled. I downloaded software that I had waiting to install, and verified ccs enabled on my 21 MY with just replacing the board and doing a software update. Woot woot! Thanks all!

 

[minnesnowta]

I have a '21 MY built 10/2021. CCS was not enabled.
I called the Glendale, AZ store this morning and they had the 00-B ECU in stock for $140. I went down to pick it up. They said they had more ECUs but could not give a number of how many. I installed tonight.

Powered down in the menu, unplugged high voltage connection under the frunk, unplugged negative terminal on the 12v, removed plastics, installed board. I reassembled everything. At this point ccs is still not enabled. I downloaded software that I had waiting to install, and verified ccs enabled on my 21 MY with just replacing the board and doing a software update. Woot woot! Thanks all!

Thanks for the info! I should have done the power-down steps like you did, but I figured what's the worst that could happen since none of the connectors seemed high-voltage. Also, good to hear that a regular software update also enables the new ECU rather than having to deal with service mode.

I guess I should have made a new post with a title more appropriate for replacing the ECU rather than lump it under "how to remove trunk trim...".

I should also mention that I have successfully charged at an Electrify America station using the CCS adapter from Tesla South Korea (imported via Harumio):

 

[shyamster]

Has anyone tried this with a 7-seater model Y? I can go all the way to getting the side trim loose but the bottom part of the trim is firmly stuck below the third seat

 

[theoriginalkar]

I have a 21 Model Y. Is there a detailed post out / instructional guide on how to access the ECU? Visual aids are welcome!

 

[Yipsan]

just found this while i am preparing to install tomorrow!