Does anyone know where I can find the truck's 3G/LTE module?

Ahhh I did not know this, I agree, a 5v line may not need shielding, though it was simple enough to do, and it just might make a difference. It is feeding a mic.

 

**IMPORTANT EDIT**
Read the follow up replies to this post for the full information. TLDR is that you’ll likely need to get 5v from somewhere other than D37-15.
**EDIT END**

Ok, I jumped the mic connections in my Tacoma and used a patch from my head unit's USB connection to power it. Everything is working correctly and I'll post some pictures but I realized as I went to post this that there's a way easier way to accomplish this patch. All the wires you need are on connector D37 of the DCM and you don't need to bring power in from an outside source.

First thing, disconnect your battery, you're going to be moving an airbag and working on or near critical electronics. Here's a video showing you how to access your ECU which is right next to the DCM.
https://youtu.be/V0LdhmlkhPY
(I don't understand how this is a perfect video that easily explains how to do this, but is the only video on that channel and the channel only has 19 subscribers. It's Internet gold!)

Tip: get a small box or something to set the airbag on so it's not dangling by the two thin wires while you're working.

Next, I used a plastic trim tool to press the latch on connector D37 so I could wiggle it out. I didn't disconnect anything else.



Tip: Leave D38 alone. That's the speaker connection running through the DCM. The door speaker and dash tweeter work when plugged into the DCM, even with the fuse pulled. It seems to have some kind of bypass built in.

Here's where I did a bunch of extra steps to run wire down from my head unit to the DCM. Don't be like me. Instead use some jumper wires to accomplish this:


What's going on here you ask? Well, using knowledge and diagrams shamelessly stolen and hoarded from across Tacoma World, including this very thread, I'll attempt to explain.

Here's the connection from the microphone to D37:


You can see the following information:
D37-5: power for the microphone (5v acc)
D37-6: microphone in +
D37-7: microphone in -
D37-23: ground for the shielding

Here's the connection from the head unit to D37:


You can see the following information:
D37-16: microphone out +
D37-32: microphone out -

D37-15: power for the DCM's USB connection from the HU (5v acc)
D37-31: ground for the DCM's USB connection from the HU

So here's the jumped connections we're making:

D37-5 <-> D37-15: microphone power (5v acc) from the HU
D37-6 <-> D37-16: microphone + in to out
D37-7 <-> D37-32: microphone - in to out
D37-23 <-> D37-31: shielding to ground via the HU

What should be used to make the connections? I basically used hobbyist breadboard wires with the normal pin shrouds removed and replaced with heat-shrink to prevent shorts. The pitch of connector D37 is smaller than the normal 2.54mm spacing on a breadboard so you can't fit the wires next to each other with the shrouds on. The square pins do fit in the connector hole, but very tightly which is actually good for our needs. They won't easily fall out. I did trim about 1/3 (2mm) of the pin tips off because some wouldn't go all the way in. I have pins and a crimper so I made short wires but you can buy wires with two male ends.

Example wires:

$7 ELEGOO 120pcs Multicolored Dupont Wire 40pin Male to Female, 40pin Male to Male, 40pin Female to Female Breadboard Jumper Ribbon Cables Kit Compatible with Arduino Projects

https://www.amazon.com/dp/B01EV70C78

Here's pictures of what I did, but like I've explained, you can do it easier (probably).






Disclaimer!!!
I'm just some dude on the Internet. Don't trust me. Think about the information I've provided and decide for yourself if it seems legitimate. I'm not responsible for your actions. I haven't actually tested the exact instructions from above, but I will probably go back and re-do my work soon (we all know this means anywhere from this weekend to just after the heat death of the universe).

I have non-JBL premium audio with navigation for my head unit. I'm only assuming that all 2020+ model head units have these same connections to the DCM.

For reals, disconnect your battery. The airbag could be a real bad time and the ECU could prevent your Tacoma from running at all if something goes wrong.

 

Figured I'd throw my $.02 in here, as I banged my head against this wall for months when I first got the truck. If you have a unit with the SOS button you need to supply 5V to the mic for it to run. I see that dmca is using the 5v "power supply signal" on pin 15 on the D37 plug. This was my first plan, but did not work. On my truck that 5V rail would droop to about 3.2V under load, and the mic would not function. I suspect because it's a power Signal rather than an actual power rail. I instead used pin 19, labeled as "Power source (IG)" in the manual (11V-14V) and ran that into a buck converter and out to pin 5 to take it down to 5V. That's been working great.

 

Good to know. Like I said above I hadn’t tested that. I’m using 5v from the USB port at the head unit currently. I haven’t seen a full breakdown of the DCM connector so I’m not aware of the other pin’s functions. Thanks for adding your knowledge.

 

It’s interesting that didn’t work because on the head unit side those pins are labeled as DCM power supply.

 

Oh, that's important info. Here are screengrabs of that pinout. Didn't realize you had done the USB instead, thought maybe you had just been luckier than I.
In that case yeah, anyone looking to do this: Can't use pin 15, voltage will droop.

 

DM me if you are serious about buying a Bronco. '77 Bronco Sport Wagon...

 

That is strange, because the actual DCM power supply is Pin 1, and is always on regardless of ignition status.

 

Here's how I did it, maybe it'll help someone. I couldn't fit any kind of project box in the space available, so I removed the DCM board from the case and housed my buck converter in the DCM case. I could not find a matching connector for D37 to save my life. I looked everywhere. My only thought was to buy another DCM and rip the female connector off the board. The cost was high enough that I just patched the other ends of the wires you see into the male connector and called it a day.

 

I guess you could de-pin R50-10 at the head unit and move it to the R49-23 position. Then you could use D37-15 for microphone 5v power without having to run a wire down.

 

Yeah I'm sure there are a lot of other ways to get a good 5V signal. I didn't want to mess with tapping or re-wiring any existing plugs so this is what I came up with. Can be completely reverted if necessary, with the only permanent change being that small hole I drilled in the DCM case to put a ground lug on.

 

I wonder what OP is up to now....possibly fashioning a tinfoil hat out of non aluminum tinfoil?

 

I like to believe that they're out wheeling and living life instead of spending all their time on TW. That's the dream, right?

 

Going to revive this thread to add another option…
I researched this when I had a 2017 sport. I found that the DCM transceiver has its own connection to the shark antenna on the roof. That can be disconnected and replaced with a “dummy load” resistor that would convert the RF energy into heat thereby negating most, if not all transmissions.
In this case, your hands free would still function as well. At the time I had found the correct item on Amazon. It was coaxial connector with a 5w dummy load resistor built in for just such an application. You have to match the connector size to your DCM transceiver to get the correct one. This option retains the factory GPS.
I will be working to identify the correct part numbers to share with the group.

If you eliminate the ability of the truck to “call home”, it cannot share your data- nor can XM radio sell your location/speed info to insurance companies (which they currently do now)

 

Did cellular connectivity start in 2020 or do all third general models have this?

 

I am not sure…
Sold the 17 and have a 21 now- which does have the DCM cellular connection

 

Does killing power to the DCM also kill power to the Sirius XM radio?

 

No, the DCM is down by the ECM behind the glove box, and the SXM receiver is a board in the head unit.

 

Glad I’m not the only one who’s done this

 

This has been discussed before in:
Simpler solution for disabling the DCM telematics - Silencing Antennas | Tacoma World
See post #12; it was found not to work entirely. Seems those elusive radio frequency waves like to go where they want. @Disgruntled Scientist did a lot of work on this.

I have some confusion, it is my understanding your 2017 did not have a DCM, don't believe they started until 2020.

The DCM has TWO cellular antennas; the main cellular antenna to the shark fin on the roof and another backup cellular antenna just below the surface of the dash in the middle; in that same under dash antenna assembly is the GPS antenna for the radio/navigation. The DCM GPS antenna is in the shark fin; the radio's AM/FM antenna as well. This is how it is on my 2021 OR AC.

I removed my SIM from the DCM, not something most will want to do, but an electronic hobbyist should be more than capable. Now, that completely eliminates any cell communication to Toyota.

The radio Satellite antenna goes to the shark fin; that makes for four antennas in the shark fin.