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Discussion Starter #1
Sorry if this has been asked before. Has anyone installed any aftermarket BSD / rear cross traffic detection units in an Outback with Starlink? Found a couple units that look promising, but understand that they can trigger emails from Subaru via Starlink even if not subscribed.
 

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2019 Subaru Outback Limited 2.5i WGM
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The Starlink service is provided through a cellular modem built into a unit called the DCM (Data Communications Module) which is installed right below the stereo/nav unit. It wakes up periodically, and polls various other modules using the car's CAN bus.
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Unless your aftermarket Blind Spot Detection unit actually connected to the car's CAN bus, and the DCM somehow knew how to poll it for information (both of which seem very unlikely), then the Starlink service will have no information about this unit being installed.

I don't think any of the safety systems (LDW, BSD, AEB, etc.) actually provide data to the DCM anyway; however there is a "crash" signal which connects directly to the DCM in the event that the car's impact sensors register an accident. This is how they know to call up your car (yes, it has a cell phone number) after an accident.
 

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Discussion Starter #3
Thanks for the reply. Apparently the unit connects to the CAN-BUS to monitor speed and maybe turn signals. Speaking with tech support at the company that manufactures the unit, they said there's reports that owners get constant emails from the Starlink system even if you're not subscribed to the program. Didin't say specifically what the notices said. Also saw another unit that said similar and noted that there's a problem with OnStar, also. They said the unts will work properly, though. Just trying to get a handle on what type of unit to install as there are others that don't connect to CAN, but I'm not sure if they are as good.
 

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That's surprising. Maybe the DCM sees the device (if it has the same CAN bus address as the factory BSD unit, for example), but then can't talk to it properly.

I know that the DCM is at the "top of the food chain" on the CAN bus. That is, no other device in the car relies on the DCM being present to operate properly. The DCM just needs to see the proper devices, and polls them, or picks up broadcast messages.

I know this because I removed the DCM from my car, and bypassed the speaker and mic connections, and there are no warning lights or other errors. All the safety systems work properly. This also makes sense because the DCM (and the Starlink service), are not available in many markets.

By the way, the mic in your car is always live, and always connected to the DCM and its cell modem. The Starlink service can listen to the sounds in your car at any time. Will they? Probably not, at least not without you requesting help, or them letting you know they are listening. Probably.

Within a month after getting our new Outback, Subaru sent an email saying that our washer fluid was low. I find it extremely creepy that a car company is continuously monitoring where my car is. So, I contacted SOA, and had the Starlink service cancelled, and all emails and messages halted. I then removed the DCM from the car. I haven't heard a single peep from them since, not even "Your car is offline! Please bring it to a dealership".

And yes, I lost the emergency services and crash notification. This is worth it, in my opinion, to not have big brother watching. And yes, my cell phone can always be tracked, I know. But I can turn that off, or replace it, pretty easily. Where is the "OFF" switch for Starlink? I'm not paranoid (honest!), I just feel the need to resist the assumption that my personal data is the property of Subaru of America. I know, I should just give up.

I have also wondered what happens when the DCM wakes up, finds a marginal cell signal, and then gets into some kind of error-retry-error-retry loop. Could this be the source of some of the battery drain problems which seem to plague some owners?
 

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Discussion Starter #5
"Maybe the DCM sees the device (if it has the same CAN bus address as the factory BSD unit, for example), but then can't talk to it properly. "
This is what I was thinking.
After reading your experience, I'm tempted to give the BSD unit a try and if a problem, just remove power to the DCM. I was leaning towards not using Starlink anyway. Thanks!
 

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Your profile shows a 2012 Outback. If that's correct, then your generation of DCM may have relays for the front tweeter connections. This means that removing the connectors (and power) to the DCM will still allow you to hear normal audio from these speakers, as the relays default to the normal connection.

However, later generations of the DCM changed to using active elements (FET transistors) to perform the switching between normal audio, and Starlink audio. This means that if you remove the power to the DCM, you will lose audio to the front tweeters.

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Another possibility is that the aftermarket BSD unit is somehow interfering with the DCM's ability to communicate on the CAN bus. I've had this happen with an OBD code reader plugged in to my 2012 Impreza: if I leave DashCommander running on an Android tablet, and then turn off the car and turn it on again, I will sometimes get a check engine light as the car turns on. The code is that the ECU can't talk to the TCM (transmission control module). I think the OBD module is trying to talk to the ECU when it is turned off, and the CAN bus requests are queued inside the OBD module. Then, when the ECU is powered up again, the OBD reader performs all the reads at once, and there are so many that other communications are temporarily blocked.

The CAN bus doesn't really have a mechanism to shut down a node which "talks too much". It is assumed that all modules on the bus will be well behaved. There are some very important modules on the CAN bus, so making sure that any device you attach is well engineered is very important. Here is the CAN bus architecture for Gen5 Outbacks. The factory BSD units are shown as "RDR" (Radar), and there is a private CAN bus between the left and right units, so only one connects directly to the main CAN bus.

Also, note that the DCM is not shown on this diagram, but it must be connected to the BODY-CAN bus. Haven't traced out the connection in the wiring diagrams, though.
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Discussion Starter #7
Ha! I had forgotten to update my profile...its now a 2019 model. Thanks for passing that info on. Saved me from having to re-hook up the DCM, as I wouldn't want to loose the speakers.
Instructions (non-Subaru specfic) have the unit connecting to the OBDII at the 6 & 14 (CAN - J2234 hight & low) location. This is all above my pay grade, but it's interesting.
 
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