Subaru Starlink does not use satellite communications. No connection to Starlink the satellite company.

 

I wrongly assumed Subaru Starlink uses satellite communications, but I did know it was not at all connected to Starlink the satellite company.

 

1-I believe you're mistaken about Starlink using satellite communication. Subaru's Starlink uses cellular services from ATT. Please do not confuse Elon Musk's satellites Starlink with Subaru's cellular Starlink system. Subaru's Starlink uses ATT cellular services. Musk's Starlink is a satellite internet service for those willing to pay premium costs for internet services.

My Subaru dealer glared at me after describing Starlink features when I replied 'So I can use my phone/MySubaru app to remote start halfway around the world?" He simply said "Don't do that!" Cellular is cellular and all interconnected to allow all phones to connect around the world as long as a cell tower is nearby and is part of the world wide cellular network.

Once out of cellular tower range (last time I checked, it was a 3 mile radius), a cell phone is effectively dead until reaching a tower. I found a dead spot in NJ, in the same area after several trips when listening to Sirius XM radio. Dead spot. I didn't need to take a call or make one so I'm not sure about that part of cellular dropouts.

2-The data communications module (DCM) interacts as the interface between celluar services (Starlink and phone) and the entertainment head unit. The automatic muting of radio, podcast, plug-in/bluetooth audio is the dcm interrupting/muting audio to allow incoming cellular phone texts, calls and outgoing calls made thru the vehicle.

If you remove the dcm, you effectively disable Starlink and vehicle phone services unless the dcm bypass information states differently. Subaru Starlink and vehicle cellular phone services will not work without the DCM. Please correct me if I'm mistaken. Your cellular phone still operates independently from Starlink and infotainment system.

 

Replying to your generous comment via your numbering…
1 - Sorry to confuse with the Musk monster Starlink satellites that clutter our dark skies, but yes, good info that Subaru Starlink probably doesn’t use any satellite communications. I get now that the green overhead console light just means the DCM is alive and ready to try SOSing via cellular. Not that such will be successful.
There is a lot going on with cell tower usage and mobile services sharing and being linked, but somehow Subaru‘s contract with AT&T doesn’t plug into that at our location. Verizon uses a tower on top of Wawona Point within view of our cabin that works great, so everyone in our small mountain community uses Verizon. AT&T is present, but only in certain areas around town and not usually strong enough for voice. AT&T cellular is absolute zippo at our cabin, otherwise I’d try a cell signal booster that boosts weak cell signals.
(AT&T again makes a “Cell Booster” that serves as a mini cell tower where there is no service, but they absolutely require having an AT&T Wireless plan to do the setup. AT&T stubbornly won’t let us get one and set it up without a wireless plan - Even though our internet connection here at the cabin (which is how the mini cell tower booster works) is AT&T Internet via DSL.)
2 - I guess my hope to find out more about the Bypass still stands. It must not cut out the DCM entirely, but just removes it from using Subaru Starlink. So… With the Bypass maybe a mobile phone connected to the car via Bluetooth still works to yap or play music. There’s some reasons along the lines of keeping audio functions for which people install the Bypass, rather than just removing the DCM.
Logically one would think unsubscribing to Subaru Starlink could stop the problem of the car attempting to send that car-shutdown status report to the Subaru servers via AT&T, but I’m guessing the car side of the “big data info collection” world would still try to happen. And the DCM Battery would still wear down and die from the continual searching for AT&T cellular. (According to earlier lawsuits there were non-hybrid cars with regular car battery drainage issues, perhaps pushing Subaru to introduce the separate small DCM Battery.)

 

Subaru uses the DCM to collect data on the car and how it is being driven, whether you have an active Subaru Starlink account or not. That data is by default shared with other parties, including insurance companies and data brokers.

Disconnecting the cellular antenna cable from the DCM will limit the DCM's ability to communicate with the outside world, while retaining some in-car functions.

Fully removing the DCM is the only way to completely get rid of the data gathering and tracking functions (Which is what I did.)

Just bypassing the DCM won't stop it from being a parasitic drain if that's going on now. The only way to do that is to replace the DCM or remove the DCM.

 

I haven't looked into service manuals insofar as which antennas are connected to it and/or the head unit. Subaru service manuals are not diy friendly compared to GM, alldata or Mitchell data.

If you choose to disconnect the DCM in its entirety or just the main electrical/electronic connections, it may not affect the head unit but may trigger error messages. You can consider disconnecting the backup battery to the DCM and see if error messages popup, allows Starlink to operate when in range of ATT's cell tower or it halts Starlink altogether. When Starlink fails to 'call home' periodically, whether subscribed or not, Starlink headquarters might attempt sending an error message to your infotainment display and/or email you of an issue. It would be trial and error for you to examine what's behind the infotainment unit/DCM, connections for power/communications/antennas. In theory, disabling the DCM, completely or partially should not interfere with the infotainment system. The DCM controls cellular signals to the infotainment head unit, interrupting audio to switch to incoming or outgoing calls, is on standby mode before and after.

I came across a power graph related to Subaru's parasitic power draw when ignition is off. One part showed a spike of approximately 0.25 amp, a quarter of an amp but momentary - a few milliseconds. The rest of the graph depicts normal parasitic current, below 0.070 amp, <70 milliamps. Power for memory chips, clock, ecm memory related to emissions parameters, and other memories for modules. The quarter amp spike, I think, is Starlink calling home. No mention of frequency of transmitted signal and I assume it's well within guidelines meeting minimal battery drain. Service manuals don't reveal the dilemma when Starlink's backup battery dies and Starlink begins calling home, duration of transmitted signal and frequency (once a minute, fifteen minutes, whatever) that became an issue with discharging the main battery after the Starlink backup battery died that required either replacing older DCMs or software updates to halt the error. I think older 3G DCMs are incompatible with 5G and created the TSB for removal and inserting a bypass module or owner desiring Starlink services when subscribing with an updated DCM.

 

I have had zero errors in my 2024 resulting from removing the DCM, and no communications from Subaru about it.

 

So this is embarrassing.

Trying to send someone an explanation of what I did to remove the DCM... and I can't find the image I had that showed which ports on the DCM and "control unit" are which.

Anyone happen to have the ports diagram for a 86201G / Denso DNNS122?

 

This is an image of the back of the model head unit in question.

I am 90% sure from memory that the upper right double connector is FM/AM, the blue connector is Sirius XM, the lower right grey connector is GPS, and the brown connectors are for the USB and AUX ports. The two big white connectors are data connections to the car.

Just need to be sure before I give someone advice based on this, I do not want to have someone pulling the wrong plugs based on what I said.

 

Thanks to @Nutjob1 I have the image I need, and info to spare.

 

This reminds me, why on earth does the non-Nav head unit have a GPS connection?

 

Maybe Starlink wants to know where to send the ambulance, and you're justified in your dislike of being tracked.

But.. The unpopulated common module is a reasonable take as well.

 

Just guessing; the GPS antenna is baked into circuitry whether used (in earlier head units using Tom Tom stand alone nav) or not. I'm still attempting to understand Subaru electronics and GPS is a little confusing between AA/Carplay (presuming nav is from phones with their own gps, bluetoothed onto the screen, bypassing the gps antenna in the head unit/dash. As I let electronics stew in the one cell between my ears, I'm tasting from perspective as time passes.

 

Nah, the DCM lobotomy should be plenty.

 

OK, you dragged out the geek in me with this reply. Perhaps on a technical level, the infotainment/head unit is being lobotomized; the DCM removal to halt Starlink cellular services. Without Starlink, surreptitiously eavesdropping while providing services and data mining, DCM removal halts gossiping.

On another issue, this may halt over the air updates since DCM removal blocks automatic OTA updates via cellular (ATT) services with or without Starlink subscription.

 

If Subaru did useful OTA updates, it would be like Tes. (ducking!)

By the way, my other car brand, Lex, does not do useful OTA updates either. 1 update in 18 months, and it was for a meaningless radio/nav update. Real updates require a trip to the dealership and hours while the techs figure out what to do.

 

Well, there are updates and then there are updates. The geek in me says vehicle electronics may not be keeping up with faster than unexpected issues inadvertently popping up like the two people discovering a flaw while researching a Subaru topic, exposing ota communications to anyone interested in illegal access. They reported their discovery immediately to Subaru with Subaru immediately updating software. These two people could have offered or sold the info to the dark web but they didn't and made news headlines.

I don't obsess as others may about ota updates. In the overall scheme of things, having ota updates is way better than dropping off my cuv at the dealer and not knowing how long I'm without, unless a loaner is provided. Guess how many loaners dealers will have to have when a everyone needs updates? The scheduling nightmare isn't pretty since this cuts down on profit making services and puts owners off for "We don't have an opening until 2039".

Ota update is useful and most likely a sign of ever faster electronics and issues that may pop up.