how to disable the DCM/Telematics unit in the car

So, I haven't pulled the DCM yet. Waiting for my new tweeters to arrive before I pull the dash apart again and pull out the head unit to gain access to underneath it (where I assume the DCM resides).

For the time being I have pulled the fuse for the DCM and replaced the fuse with a toggle button. This is the wiring harness I made. It's a little more complex simply because I wanted the button's internal lighting to work as well so I had a visual indicator of when it was on.

The button fills one of the empty (poverty) button slots on my driver side area. This allows me to cut power to the DCM unless I want to use the microphone. With it off I get zero status reports about my vehicle on the app. No TPMS, no door indicators, no odometer reading, nothing. But I still don't trust that it's fully disabled AND it supposedly has its own internal battery. Hence why I plan to pull it. I also have SMA Male / RP-SMA male plug RF coaxial Termination dummy Loads 1/2 W DC- 2.5GHz 50 ohm caps to replace the antennas on it to reduce the range at which it can broadcast if I decide to leave it in.

Ideally I would like to buy a cheap (~$25) dead telematics unit off ebay that has matching plugs, desolder the plugs on it and make my own jumpered connector that plugs right into the factory wiring harness. I don't like the idea of just jumping those pins directly on the harness, I want to make my own connector that is reinforced and will properly seat itself.

I'm curious to see if anyone else has done it but I really doubt it. The Prius crowd is very... complacent. The Tacoma boys want their stuff to work and don't want outside interference, I fck with that vibe.

 

An analogy of types, so to speak, near 25 years ago when wireless started using the 5Ghz band or the 802.11a band, there was a lot of discussion about safety of wireless transmissions of 5Ghz and above. like microware towers and such. Not so much discussion about those issues these days since the discussion now focus more on current developments of those older technologies. Don't forget, about those who keep pumping new stuff out for public use while telling us all that they are safe.
One really has to be willing to choke on their words while believing them or give those words and completely different meaning than what most other people would think them to mean.
Geeezz, Politics and Eco nomy$ and the human quest of supremacy does have it's own unique set of downsides to it self. Ignored by many.
My old man used to tell us as we were growing up, "The more we know, the more we understand how much we don't know"
Nikolai Kardashev - Wikipedia

 

The easiest way of doing it would have just been to refuse all connectivity trials when you first bought the car. If you do that, it automatically and semi-permanently* disables the DCM.


*It can be turned on again at a dealership, but it's a royal PITA and takes between days and weeks.

 

It's still transmitting even if you opt out of all services.

Even if you do opt out, that's not a guarantee that they're not collecting, using, and selling the data they get. See the recent GM lawsuit: https://gmauthority.com/blog/2024/03/gm-hit-with-2nd-onstar-data-collection-lawsuit/

Also, look at the kinds of issues that can arise from shitty programming, like parasitic drain: Subaru Battery Drain due to shutdown of 3G net - Subaru News & Rumors - LegacyGT.com

Privacy agreements don't matter anymore. If a company can get your information and collect it, they will, and they will sell it, because the penalty will likely be cheaper than the profit made from it.

I said it elsewhere about this... you guys lock your doors, you roll up your windows, but you give ZERO consideration to digital security. You just blindly trust that these things will never be used against you and will never fail in a way that will cause you problems. If you're not using any remote services then there is ZERO reason to keep the DCM hooked up/powered.

The minute some 10th grade drop outs figure out how to remotely unlock your car, they're going to thanks to the DCM and remote services.

You are exactly the kind of person I speak about when I say that Prius drivers are complacent.

 

You got some proof that the DCM stays transmitting after opt out, or just some conspiracy theories? Because I know Toyota dealerships can't transmit to it after it's been disabled unless they jump through a ton of hoops.


Also...

Something like 10 years of different types of DCM in so many different brands and models of cars. That's plenty of time for hackers/crackers to come up with something and spread the knowledge to car thieves all over the world. So why isn't it already happening thousands of times a day?

You can call me complacent, but I call you needlessly paranoid. There are so, so many things to spend your mental bandwidth on to make your world a happier place, I can't imagine wasting all that energy on things to make yourself worry more and be negative.

Say you're correct and somebody manages to hack into my DCM and steal my car. How is that any different to me from them breaking my window and hotwiring it some other way? If they want to get in and steal it, they're going to steal it one way or another. I'm not going to deprive myself of the functions of the car that I enjoy using just because of a remote possibility that something sorta bad might maybe happen someday possibly. That's just a tiring way to live.

 

The most smooth-brained response ever. Congrats.

It's not a conspiracy theory, multiple lawsuits have been issued to automakers for collecting and sharing customer data when they weren't supposed to. I even linked the latest one. It's not a theory if it's been proven to be real.

"Because I know Toyota dealerships can't transmit" Based on what? You KNOW? Ok, where's YOUR proof?

"So why isn't it already happening thousands of times a day?" It HAS happened, example Hacking cars remotely with just their VIN All it takes is for a weakness to be found and then your car is compromised. It's just a matter of time til someone finds the weak point to attack. Just like we see with the latest canbus attacks on vehicles.
How to Get Away With Car Theft: Unveiling the Dark Side of the CAN Bus - VicOne


"How is that any different to me from them breaking my window and hotwiring it some other way?" First, no one 'hotwires' modern cars. You need to deal with authentication, immobilzers, etc. Second, why bother locking your front door if thieves can just break a window to get in? Do you see how ignorant you sound? WELL IF THE THIEVES CAN STEAL MY CAR ANOTHER WAY THEN I SHOULDN'T BOTHER MAKING SURE THEY CAN'T STEAL IT THIS WAY. Wow, great logic there.

This thread is not meant for you. Clearly you are happy with your situation. For those of us who don't use remote services and as such do not have any use for the DCM, we're gonna tinker with it. Because some of us didn't buy a 5th gen prius just to have a circlejerk about who gets the highest mpg. Some of us like projects and like modifying things. Not you though.

 

If you guys are willing to write a guide on how to do it with pictures and the likes, I'd be interested. From what I've read about the Tacomas, it didn't seem super easy and I am not sure the Prius is exactly the same.

Also if you have a pictures of the connector, I can try finding the matching one or its parts number elsewhere.

As a side note, when using the poverty buttons, did you just drill into the blank one or did you find a replacement switch? I just learned the blanks are not the same size housing as the regular switches and it's horseshit

 

They are the same size. The one on the far left upper area is larger and is meant for the light adjuster switch. Can be seen here:

It's bigger because it needs room for the components in the rocker knob.

Otherwise the buttons are the standard toyota button size. The button I'm using fits just fine and is labeled for corolla but it's a standard Toyota panel button.

Do note that Toyota is weird and has notches on their oem switches and those fit certain switch holes. Just today I used a dremel to cut all the notches off the switches so I could move them to any position I wanted. Now my AHB and front defrost switches are next to my gas cap switch because I don't use either function really so they're in low priority area. Meanwhile now I have the upper row of switch holes to use as I want. One for DCM, another will be for a gain knob for my subwoofer, and another will be for aftermarket illumination.

 

That’s your dad?

In case anyone else is curious:

DCM = Data Communication Module

 

Have read many of those reports. And while there are certainly some devious car makers, Toyota has never been implicated in these subterfuges.

In fact, Toyota goes above and beyond the other car makers. They completely separate out the insurance reporting service. They accurately describe its function, and make it easy to discretely disable.

Claiming Toyota is violating their legally binding privacy assurances qualifies as an extraordinary claim. Extraordinary claims require extraordinary proof.

Given the complete absence of any proof implicating Toyota, this qualifies as a conspiracy theory.

 

So in a semi related area- I hate that I have to subscribe and pay (!) ATT to get my display to mirror what's on my phone, and I refuse to pay. I already pay for unlimited cellular on my phone. I just want my car to integrate with my phone, and not be stuck with a different provider to duplicate stuff I already pay for and that I am happy with. Is there any way to make my gen 5 act more like my gen 2 or gen 3?

 

FORGIVE me if I asked a question that has already been covered in detail by others. Prius chat has gotten huge!

 

I was wondering why I had you on Ignore. Now I remember...

 

Ohhhhhhhhhhhhhhhhhh, Toyota's never been caught so they must be the best boy corporation who would never do anything bad! /s

You know what's weird? If I said I was going to remove my back seat, there'd be no one coming into the thread trying to dissuade me from doing it. It's REALLY odd how so many people get so defensive about other people wanting to disable their car's internal cellphone (which it is, it even has an e-sim). Suddenly everyone comes out and is like "hurrrr why do you need to do that??!? toyota doesn't collect your data! you shouldn't do that!". It's so weird.

And it's not even JUST about privacy, as I stated above. It's about heading off potential issues such as the parasitic drain we've seen from other past DCMs, and it's to reduce attack surface area of the vehicle. Canbus hacking wasn't a thing... until it was. And now it's a major issue. DCM hacking, while it has been limited so far, MAY become a larger issue. Additionally we're seeing reports such as how automakers want to have vehicles that can essentially reposes themselves back to the dealership ( Ford Applies to Patent Self-Repossessing Cars That Can Drive Themselves Away ), and things like California toying with the idea of having cars be limited to an area's speed limit ( New California bill could require cars to have speed limiter technology ). Removing the DCM potentially prevents external control like that as well.

Again, I have ZERO use for any service provided through the DCM, and as such it's a fun little project for me (and maybe others) to mess with. If nothing else, it becomes information for the community at large. So the opposition to anyone doing it is really stupid.

Cool story, grandpa. Great contribution to the discussion.

 

Telematics requires an antenna, right? Why not disconnect that?

 

And a cellular modem. Believe that prior models had a fuse specifically for that modem.

Removing the antenna or fuse should easily, and more importantly, reversibly render any wireless connectivity completely non-functional. And with the antenna removal, it shouldn't impact the odometer and other systems, as areas without cellular data coverage remain quite pervasive.

Conspiracy theorists are going to conspiracy.

 

To confirm, you have absolutely no evidence of Toyota ever doing what GM has recently be caught doing, or of a Toyota connecting remotely to a vehicle from which an owner has asked Toyota to disable remote connectivity?

Even for the tinfoil hat types, baffling to through all of this to disable the system when disconnecting the antenna would not only accomplish the same, but probably do so in a way that doesn't cripple the cars odometer and other systems.

It's hitting this with a sledge hammer, when a pair of tweezers would do.