Yes, I read both numbers in the photo
I suspect the part number is the number for the outer casing and the assembly number is for the whole thing.
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Does anything need to be changed software side to enable a DIY added OEM trailer wiring module for Model 3?
- Thread starter rotarypower101
- Start date
I suspect the part number is the number for the outer casing and the assembly number is for the whole thing.
Again Thank You to anyone willing to help and discuss this topic, still trying hard to find clarity on this informations details.
It's possible I misinterpreted that thread?
u/majeric said he was getting the parts installed by tesla in june 2023, but I didnt see anything that indicated the trailer module was/was not flashed while at tesla, or that flashing the module was specifically necessary?
May be totally missing some detail? And apologize if I am misunderstanding anything.
I believe Tesla's "Toolbox" software was almost certainly used to expose the "Trailer Mode" button, as over here that button is not exposed on Model 3 normally. But that is a completely separate detail to if the tesla module is active immediately when plugged in.
Fortunately we as endusers can get access to the Toolbox software, and enable the "Trailer Mode" functionality.
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Sorry to belabor the point...Have another read through @majeric's thread linked in post 16. He has done what you intend to do and all your questions are answered, albeit an experience group of one!
People saying something structural will be missing are mistaken. Or rather they just don't realise the towbar, or hitch for you, is not just the detachable ball, but also the structural crossmember that the ball attaches to. There's no physical way to fit the ball to your car and be 'missing something structural' since you must fit the crossmember! Note that in the UK/Europe the OEM hardware is a vertical detachable ball setup made by Westfalia. You will have a similar crossmember that likely provides a standard US square receiver, I would guess. So not same part number as majeric used.
So seems like mechanically and electrically it'll all work out fine. However, big however, sounds like you want to actually tow and not just fit a bike rack, which on paper isnt permissable with a Model 3 not factory equipped for towing. Well that's up to you! As above it will physically work, but if anything happens you could be in hot water.
But I have to ask - why all the trouble? I heard from a friend that in the land of dreams you just pick up a Ford F150 for 100 bucks and it can tow your house.
On post 16, he says
Is this what is being referenced? (emphasis added)
I didn't read a followup Confirming this detail.
Think I will need to ping him directly and ask. Maybe he is able to clarify this point.
What is the other comment you are referencing the module is active explicitly when plugged in?
Its probably obvious, but have read through the thread multiple times slowly, and don't know what you are referencing?
If I missed something blatantly obvious apologies on that also.
Will you link the comment explicitly, sorry for the specificity, thats what I am trying to find Is a unambiguous answer.
I think you guys are correct, I think I have misquoted the part number, which I have incorrectly transposed directly from a photo.
It sounds like the module/ECU "part number" might be the second string of characters?
And I think the 8 in my part number is actually a "B" , even though it sounds like that string is irrelevant.
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stopcrazypp
Well-Known Member
"A picture is worth a thousand words" so not sure why people haven't used them as visual aids yet. The install guide in that third party one tells you to discard two OEM brackets in the trash and install theirs:
They introduced the access cover around 2019 and a possible NA tow hitch briefly appeared on the catalog in 2021:
Tesla hints at finally releasing Model 3 tow hitch in North America
You can see in the latest manual in the UK how the OEM hitch bar is installed:
"The trailer hitch assembly is attached to the body of the vehicle with 6 nuts."
Model 3 Owner's Manual | Tesla
However, Tesla never released that in the US.
You can see the US EPC currently only has the ECU and doesn't have the hitch:
Parts Catalog
From this UHaul video you can see the 3 bolt threads left on each side after you remove the rear absorber from this US market 2020 Model 3:
The OEM bar would just bolt on the three holes and you discard the OEM rear energy absorber (just like how the OEM Model Y hitch is installed as per below thread).
Do you need to reinstall the reinforced bumper bar for an OEM Model Y tow hitch?
The Uhaul design (and it seems many aftermarket designs) keep the OEM rear energy absorber.
I don't see any other structural components that are different. People who say so should probably chime in (maybe they are referring to the OEM trailer bar?)
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stopcrazypp
Well-Known Member
The US does not have tow ratings on the sticker. It is not a thing for police to pull you over and check it (as it is apparently in the UK). Perhaps that is why Tesla doesn't offer an aftermarket install in the UK? Tesla doesn't either for the Model 3 in the US (only for the Model Y).
LiamPope
Member
Ok I guess it was the wording in post 37 'tow bar fitting has been booked' that gave you the impression he took it to Tesla? I just took that as booking his own time, or a friend or mobile mechanic, since as @init6 pointed out, two more posts down it was clearly done on someone's front garden, not at Tesla, and he says the trailer module functions worked without coding.
The second person I was referring to was @dhrivnak, post 21 who seemed to be directly answering your original post saying he did it and no software change needed. But I see his post is a little vague, sounds like he might not have fitted OEM wiring, and maybe just meant his hitch and lighting works fine, not specifically the OEM trailer mode function.
But go through @majeric's post again - it seems to have all the info you are seeking! But you may well have a different experience simply as yours is a US car and ours are a different market. But sounds like you have potential solutions even if the module doesn't work upon plugging in - try take it to Tesla, live without the trailer mode (doesn't seem a big deal), or obtain the Toolbox software and code it in yourself.
dhrivnak
Active Member
Just for clarification I added a 4 pin wiring harness using inductive pick ups on the wires and then added a 7 pin plug with a wire to my 12v battery. Most 7 pin plugs only use 5 of the 7 pins.
This comment answers my original question!
Thank you for taking the time to spell it out, and link the reference.
Really Appreciate it! Thank You !
Have passively been looking for this answer for quite awhile in many other section, with little success...
Glad I asked here and Very grateful to everyone taking the time to help answer what is probably a bit of a esoteric question.
pdk42
Active Member
I suspect the challenges with fitting a tow bar after the car is delivered are entirely due to paperwork and regulations rather than physical limitations. Unfortunately, these barriers are impossible to fix for the little people, so it’s effectively game over unless you want to ignore them. If you do ignore them, then you are opening yourself up to liability risk if something did go wrong.
Of course, if all you want the hitch for is for is fitting a bike rack, then that’s fine.
Of course, if all you want the hitch for is for is fitting a bike rack, then that’s fine.
As much as I’d like to have the option of towing, I’m fine with just using it for a bike rack as the roof option isn’t ideal.
I’ve actually managed to source all the parts to retrofit myself and just waiting on Tesla to deliver the ECU and trailer socket. Will hopefully fit next weekend.
Managed to get this done today. 2-hour job.
Caveat: I checked the service menu for alerts. It’s aware that the tow package isn’t active in my config and warns that trailer mode won’t function properly. But the lights work and I won’t be towing a trailer anyway so not fussed.
Caveat: I checked the service menu for alerts. It’s aware that the tow package isn’t active in my config and warns that trailer mode won’t function properly. But the lights work and I won’t be towing a trailer anyway so not fussed.
Cardo
Active Member
Seeing as the “missing structural component” seems to simply be that easily installed cross-member, I genuinely don’t understand why Tesla don’t register all M3s with towing capability, like what is done with pretty much all other cars.
I was never convinced about the structural limitation line because they've been allowing aftermarket tow hitches to be installed in the US.Seeing as the “missing structural component” seems to simply be that easily installed cross-member, I genuinely don’t understand why Tesla don’t register all M3s with towing capability, like what is done with pretty much all other cars.
Can a car be tow-rated retroactively?
stopcrazypp
Well-Known Member
As pointed out, in the US, it is not a thing to have a tow rating sticker on the car for the police to check. The hitch might have a sticker with a load rating, but not the car, as such there is no barrier to aftermarket solutions.
However, according to above, in the UK, the sticker/ rating is associated with the car.
True, but US applicability can be interpreted incorrectly by those that aren't fully aware. I'm sure most US folks know that, but lest anybody in Europe think we've no limits tow limits.
US allowed tow rating is not explicitly y placarded, but it most certainly exists. It's simply derived. There are a number of factors gating what's allowed.
Rating laws are based on:
GCWR (Gross Combined Weight Rating).
This is placarded in teh tow vehicle and is the maximum weight (typically) of the loaded tow vehicle plus loaded trailer. Some states allow the combined GVWR of tow vehicle plus GVWR of trailer as an alternative (whichever is greater).
GVWR (Gross Vehicle Weight Rating)
This is the max weight allowed of the loaded tow vehicle or trailer.
GAWR (Gross Axle Weight Rating)
Maximum weight over an axle. Usually denoted for front and back separately.
Other ratings:
Tire Load Rating:
Is a thing that exists too, and is formally defined by the DOT. But laws against misuse? Not that I've seen as regards common lightweight vehicles (their are for trucks, RV's, etc). There may well be of course.
Mfg tow ratings:
While ratings standards do exist not all mfg follow them. Nor are there any laws that I've seen. This is all about warranty first, liability second. So long as you don't violate placarded weights if you break a mfg tow rating recommendation it's meaningless from a legal violation perspective.
Personally I installed a hitch in my "Y" that allowed a greater than factory (500lb vs 350lb) tongue rating. Doesn't increase any of the placarded weights of course.
stopcrazypp
Well-Known Member
Yes, you still need to follow GVWR/GAWR rating but the point is US vehicle stickers do not have towing separately labeled on the vehicle sticker, as such there is no check for that by law enforcement, and that makes it easy for aftermarket installs.
This may have to do with towing being far less popular for cars in the US, due to the popularity of pickup trucks. In Europe, towing seems to be far more common even for small vehicles.
Cardo
Active Member
From what I’ve read, realistically no. It’s apparently to do with the homologation of the vehicle and is pretty much set in stone. But it’s odd that Tesla have essentially gone with two separate lots of homologation for cars with factory fit tow bars and those without.
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