Hopefully this can help someone else out who encounters this weird problem. This may apply to other Lexus/Toyota cars MY2022+.
NOTE: this does NOT apply to cars prior to ~2020 as those use the older 3G network (known as Lexus Enform) and cannot be fixed.
NOTE: if you have CERTAIN 2023 ES250, ES300H, ES350,LS500, RX350, RX350H, RX500H, RZ450E, UX250H you may have your own separate recall, google "SPECIAL SERVICE CAMPAIGN 24LC02"

Problem symptoms
One day I went out to drive my car (2024 IS500), the SOS module said: "Communication module activation failed.", and it did this every single time I started the car. It did this for about a month before realized it wasn't going to fix itself.

Things I tried:
1. Disconnecting the battery for 30mins - no luck
2. Deleting/re-adding the car from the Lexus app, which I had never used - no luck, but it did tell me the DCM was working.
3. Calling Lexus at their number (877-201-0237), tier 1 support had me try pressing the button and turning the car on/off. Didn't do anything.
4. Pushing the SOS button triggers a builtin message: "Communication Module is not active"

The fix:
Ask tier 1 support on the phone to escalate my case and call back when it's fixed. It was a problem on their backend.


Background:
Lexus/Toyota cars use a module called a DCM to phone home, handling stuff like the SOS emergency calls, remote start/locking, and reporting back to the Lexus/Toyota apps. It's basically a cell phone module in a box that hijacks the Bluetooth microphone (it actually provides it power), it takes over one of the stereo speakers (depending on the exact car), and even has its own builtin battery to keep it active in case the main vehicle power is lost in an accident. It can actually be removed, but then you'll lose that stereo speaker and use of the Bluetooth microphone. It's possible to make a bypass harness that reconnects those things without the DCM, but I didn't want to do that.

2024-Mar Bought the car, installed Lexus app, opted out of Main Data Consent (thus disabling all telematics in the car).
2024-Dec Communication module problems appear out of nowhere.
2025-Jan Lexus fixed their backend and the car re-connected itself.

After re-adding the car and enabling all trial subscriptions/phone home stuff, I could see partial telemetry being reported. The tire pressures and mileage were being updated! But the car didn't know any better, still complaining about the problem. And I couldn't use the app for anything.
This is the point where I called Lexus and they escalated the case. After 2 weeks they called back with some instructions. I have retyped them here, but don't do these unless they tell you or you're wasting your time. You may have a different issue.

The first time I started the car, the DCM enrolled OK since it sounded its message, or "IVR" as the tier 2 rep said (maybe Internal Voice Recording?). Anyway, it said "Communication Module Activation Complete".
I restarted the car 3 more times just to follow the directions, though I doubt it was necessary. After several hours the app updated and everything was working then.

Unfortunately, as I don't really want Lexus to sell my driving data to my insurance company, might turn this off again, and we'll see if it makes the DCM freak out again. Who knows. Hope this novel helped somebody, lol.

 

Thank you.

 

Big Brother Lexus does not sell your driving data to Bigger Brother State Farm. It does tattle if your partner has the Lexus App and looks into the Driver Pulse page however...

 

THANK YOU for making this extremely informative post.

My story is very similar to yours, so your story doesn’t surprise me. Like you, I don’t want MY driving data to be shared with anyone.

I’m a retired engineer, who had several years in the military, and continued in the aerospace/defense sector for many more years after that. Obviously, protecting information has been a part of my whole adult life.

Let me offer a few perspectives, that go back to basics and very much apply to all this automotive telematics. In the old days, when you did business with anyone, whether it was a doctor, accountant, or lawyer, any information that you provided to them was to be used only for the purposes for which you provided it. Honorable people wouldn’t even think about making money off of that information, or use it in any way against your interest. Fast forward to today and people have set up whole industries based on collecting, processing, and distributing that information about specific people, so that they can make a buck…or a LOT of bucks. Electronic data collection, processing, and distributing has made this very cheap to do, and when you put together a lot of data, about a lot of people, over a long timespan, you can learn much more about people than they would want you to know. None of this would happen if people truly respected information provided by clients.

How did this happen? Don’t we have government that is supposed to be there to protect the public? Surely they’d make laws to make this kind of sharing illegal? Unfortunately, special interests who see $$$$ for themselves, convince the politicians to look the other way. What’s even more devious, they actually WANT the businesses to collect and retain all this information, and call it business records. Why? If the government wanted that kind of data, it would be illegal for them to do so, without a search warrant based on probable cause. Now if the businesses have collected that “business data”, the government can get it from the business, and that is legal.

So businesses, in this environment, consider any data about people that they come across to be fair game for them to collect, store, and process as they see fit, unless there is a specific law in place to prevent it. When all this data is put together, it becomes very valuable…the more intrusive, the more valuable. And remember that the government is not looking out for your interest.

So we end up with car manufacturers…and this issue. Look at the kind of data that they routinely collect and sell. They not only record data in your car, like the event data recorders that all cars have in them, which you have no control over. They have a a cellphone in your car that is routinely transmitting info about where you car is, and has been, where it’s going, how it’s being driven, speed, cornering, braking etc. Even a remotely controlled microphone in your car, and in some cases, video too! Sure they say they won’t use that without your permission..but do you trust them? Should you? I say NO and NO,

When I got my new 2025 Lexus RX, I was amazed by the car and its capabilities …ALL THAT CAME TO A GRINDING HALT, when I saw that my Lexus app showed all my driving since I got the car, organized by trips, and showing the exact end points and times, even the exact route! I never asked for that to be done! Even worse, each trip included scores for braking, cornering and acceleration scores,

Now, Lexus “brand engagement center” tells me that I can disable the tracking, but that doing so will prevent me from using the connected services. I tried that, and my car went dumb! No maps at any level! NOT EVEN THE CORRECT TIME!

Time comes from the GPS satellites, and doesn’t need ANYTHING from Lexus. Same is true for GPS location-a cheap little handheld GPS from a sporting goods store does all that on its own. I’ve worked with GPS professionally. I remember GPS from the 1980s when it was in development at the USAF Avionics Lab. Anybody who takes a few minutes online reading up on how GPS works will see the dishonesty of the argument!

ALL of the services can easily be provided in a way that will protect the customer’s data.
I can address each service individually, in another post, but an example would the sending of emergency services if your car is in a crash. They might say, how would we know where to send the help. An acceptable alternative would be for them to only send location after the crash is detected.
They have no need to know where I’ve been or how I got there. And if they cared about our privacy, they would collect the minimum amount of data necessary to do the job, use it only to call emergency services, and delete it after a time certain.

If you decline the master data agreement, they cut you off from a large group of services which have nothing to do with location, like remote start. THIS IS PURELY PUNITIVE! They advertise all the wonderful capabilities that the car has, yet nowhere did I see a list of functions that will be disabled if you don’t agree to provide whatever data they want from YOUR car! SOUNDS LIKE ILLEGAL BUSINESS PRACTICES, to me. Can you say FRAUD? Can you say DECEPTION?

THEY DON’T ACCEPT ANY LEGAL RESTRICTIONS ON WHAT THEY CAN DO WITH YOUR DATA, YET THEY DEMAND THAT YOU GIVE THEM A BLANK CHECK!

 

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Thanks for sharing your experience. Please update us if your situation changes.

The fact you had to go through this whole needless experience is additional proof that Lexus telematics is working against our interest. The worst part of this is that most of these services can be provided to the customer, with much less PERSONAL information. Providing your driving data to an insurance company should require specific listing of such information and require the explicit, revocable approval of the car owner. If you, the owner, did not initiate this, you have to ask yourself if you really want to be doing business with a co-conspirator.

 

The conspiracy has MANY tentacles! it needs to get a big dose of systematic weed killer!

 

I subscribed to the free Service Connect service through the Lexus App on my phone. That unleashed the warning that the communication module failed to connect and that I needed to contact the dealer. I unsubscribed, but that did not stop the loud warning each time the car was started. Today I took the car to the dealer for an oil change and to address this issue, and the dealer did some sort of software refresh or update (not specified on the bill) which stopped the annoying warning. Dealer treated it as a warranty claim even though my car’s warranty has expired - problem solved with no cost to me other than a 90 minute round trip drive to the dealer.