Simpler solution for disabling the DCM telematics - Silencing Antennas

@Disgruntled Scientist
I don’t believe so, terminating the antenna output is two fold. One to make sure the signal does not go too far from the cellular radio. The second is keep the circuitry from burning up, if that is possible with low power digital cellular.

The only error would be a low or no cell signal indicator on the radio head.

The use of the terminator gives the cell transmitter someplace to put its power. Think back to CB days when transmitting without an antenna would destroy the output of the transmitter. This apply to most any radio type.

 

Sorry to drop away for a few days, was out after having surgery the past week.

I do remember getting that email a few weeks after installing the app and then opting out of their privacy agreement. Probably has to do with the install/reinstall rather than anything connector related.

These are definitely FAKRA connectors that Toyota is using, but looking around Amphenol's website, it looks like a Gen 3 or Gen 4 connector body instead of the available-to-consumers Gen 1/2 chunky plastic plugs. I bet the pin is connecting at times, but staying seated is the longer term problem.
https://www.amphenolrf.com/rf-connectors/fakra-connectors.html

Going back to basics, coax should carry all of its signal inside the center conductor, not through the outer shielding/braid. I cut apart one of the cable whips from the kits I've been selling (thank you to those of you that have bought them!) and everything looks about right for a thin RG-174-like coax with an inner conductor, dielectric, and outer braid. I'm guessing this is probably not our suspect.

Looking at Toyota's antenna harness troubleshooting doc, RM100000001KYYI, their diagnostic procedure checks for the outside of a coax connection (outside compression ring, not center pin) to body ground starting from the roof mounted antenna.


This tells me that the antenna on the roof is providing some kind of body to ground connection near the roof. In theory, if Toyota didn't take the lazy way out, the inside of the DCM module should also have that outer connector surrounding the pin reasonably well connected to ground on the circuit board inside the DCM. If not, any impedance mismatch between the connector inside the whip cable, terminator, outside braid of the whip, and remaining circuit board traces would turn into a tiny, very shitty, antenna.

I'm guessing you're trying to be funny, but this actually may not be far off from the next actual step; tying the SMA connector body just below the terminator cap straight to some piece of metal grounded to the chassis.

I've got about another week before the doc takes me off of light duty restrictions, but I might throw together three ring-crimp terminals on a wire with a spade lug at the end just to force a good ground connection from the end of the whip.

 

Does anyone have an easy link for instructions for removing/uninstalling/reinstalling the fin looking antenna enclosure for the roof without breaking anything? Maybe it would shed some light for those knowledgeable on how these transmitting and receiving things work.


Me, for now, i just want a better view inside the roof, i am only as far as the center light with new wiring before getting stuck between center light and the back.
I have the recommended parts, but wanted to wrap up one thing before starting another. I was trying to run wiring for cameras from the front to the back of the roof through the middle, but fiberglass fishing tool is stuck on something

 

I would love to know this too/ am interested in a streamlined roof. That fin is hideous!

 

Getting the headliner out is a massive PITA, particularly with the back plastic. I had to do it to get my NMO antenna mounts (ham radio guy, guilty) drilled through and routed. I didn't grab pictures since the novelty of putting holes into roofs of vehicles has worn off.

Here's the official guide for getting the headline out of a 23 TRD OR double cab:

 

I actually wanted to keep the fin, but maybe put my own GPS antenna inside.
Was hoping to gently remove from outside and put back, not remove the headliner, but headliner might be the way to go if i don’t have better luck soon.

If you don’t care about the function to eliminate, you could just break it, then whatever body shops do to fill before blending and painting to make it look like there was never a fin or a hole in the roof. Too much work imo

 

I have "dropped" much of the headliner, not "removed" by peeling the door molding off the pinch weld and then the latch mechanism between my two doors on the access cab. Plus the center lights and console, console is the easiest as you just pull at one of the rear corners and then the other corners. Lights were a bit to figure out. Don't remember much more than that.
First two pictures show the roof antenna connection.




Second two are of the right rear antenna connectors.

 

The pic in your post #28 shows quite a bit of difference between the "real" versus the "Toyota" FAKRA which is what makes me question the connectors. Plus, FARKAs are made in both 50 and a 75 ohm versions. How that is done is the spacing between the center conductor and the shield and the size of the center conductor.

Does your cable have any markings on it? I notice you use the word "type" to describe the RG-174.

According to Wiki:List of RF connector types - Wikipedia
the FARKA is just a modified SMB connector, nothing special, perhaps Toyota makes changes to avoid any royalties. According to your post #28 picture the FARKA looks so much better built than the Toyota pseudo FARKA. It wouldn't be the first time a manufacturer makes minor changes to fit their needs, and pocketbook. I can't wait for the weather to clear to go exploring in the local Pick n Pull.

 

Update

Tried grounding the outer connector bodies after @altitude-nerd suggested it. My first attempt used the x3 12 inch wired adapters assembled into a harness with the outer bodies wired to a crimp ring terminal for grounding. Before installing I checked the resistances from the inner pin to the outer body for verification and discovered one of my wired adapters was faulty and showed less than 1 ohm of resistance with and without the 50 ohm resistor attached. I am guessing the inner conductor and outer braid shorted somewhere even though the outer insulation and connections looks fine. Since I only had the x3 wire adapters I then tried making another harness with the x3 shorter adapters but the ring terminal crimp connections I used to make electrical connections with the bodies were too wide to allow all three connections into the DCM module at once. In the end I used x1 12 inch wired adapter (that I verified works) and x2 of the shorter adapters. I verified resistances and everything looked good. The shorter adapters were plugged into the two outer connections on the DCM module and the 12 inch wired adapter was plugged into the middle connection. I then grounded everything to a nearby bolt. Luckily the nuts and washers from the wired adapters fit the shorter adapters and allowed me to clamp the ring terminal crimp securely. End result was a little janky. The ring terminal connections were not quite the right size for what I was doing but it worked out for a short-term proof of concept. Below is pictures of the final harness and installation. After installing I went for a test drive and the truck again updated the current mileage shortly after parking and turning off... Perhaps I might try having nothing plugged into the DCM module. If the results don't change then @Toycoma2021 theory about the center pin not making contact looks a bit more likely.

 

The center pin is only one of my theories. Another is that there is a hidden antenna connection somewhere, or... a multitude of things. I wonder if TechStream can turn this module off as well? Perhaps the way @caribe makaira did it is the only way. I can't seem to find that thread right now.

 

I did a little searching on the web for the Toyota antenna connection harness to possibly repurpose the Toyota-FAKRA connectors and I think it is 86101-04210 (https://toyotaparts.ourismantoyotaofrichmond.com/oem-parts/toyota-antenna-cable-8610104210). The diagram shows what looks like a connection/plug but I do not know what it goes to.


It could be an anomaly of the diagram, but it looks like a connection to me. If so it would be the only thing connected to the front or rear antennas aside from the DCM module. I'm pretty sure this connection it is not for the head-unit.

This diagram only shows the telephone/GPS antenna in that area.

This diagram is a bit confusing but might be showing a connection.

Does anyone have pictures of the front antenna in-situ and the surrounding wiring? Alternatively can anyone find instructions for disassembling the dash far enough to access this area? My google-fu is weak and could not provide for me.

 

Is your phone still connected to the truck via Bluetooth? Even though you deleted the app, the truck could still be transmitting the data through your phone.

Also, contrary to popular belief, app permissions don't disappear just because you deleted the app. Any time you delete an app you should remove all permissions first. Toyota wouldn't be the first (or last) company to leave enough of the app behind after "deleting" to still collect your data.

 

Wow, now that we are wondering about continuity of the center signal carrier pin/cable, somewhat pleased i didn’t get to this yet. Procrastination pays sometimes….

I really appreciate yous figuring this out though.

How hard is it to rewire or manually splice together 2 snipped off cables of this type, to receive a proper connection to a resistor? Could there just be a good amount of overlap on the center conductor and a big sloppy solder together, and wrap the messy splice up, or does it need to be done more neatly and with attention to anything in particular?

In case a dodgy connection turns out to be the culprit, snipping some oem cables, or ordering the oem part seems like the next attempt to solve. And, theoretically, can’t the theoretical damage occur due to no resistor to absorb the energy?

Sorry, i’m pretty clueless on how radio stuff works. I was serious about wrapping the hidden parts in foil - hey it works for ezpass/ipasses, but in the pics, it looks like there’s not enough space to fully enclose with foil on all sides.

That looks very involved. I have no sunroof, so I hope a few more attempts at fishing will work out.

Dome light and the little hook things are easy, and easy to find howtos on replacement, little light has tabs easy to poke and free with a pointy trim tool. I got some flex, but not enough to see what’s getting the threaded metal part of the glowinthedarkfishfiber thing stuck. Instead of pulling apart further, I’m going to see if a cheap usb endoscope camera tells me enough to get by.

 

Even with Bluetooth disabled or turning the phone off the truck still seems to be communicating. To be double sure I disabled bluetooth again today and had the same result. When my phone is connected to Bluetooth it connects to an aftermarket head-unit. The aftermarket head-unit is a simple one that does not have wireless car play, GPS, or satellite radio. The GPS and satellite radio antenna connections are currently unplugged behind the head-unit and only the HD radio connection is plugged straight to the head-unit.

I reinstalled the Toyota app, verified all permissions had been removed, and then deleted the app again.

I checked my home wifi and could not find my truck as an online or offline connected device. The aftermarket head unit can recognize and change car features (like how long the lights stay on after closing the door). I checked the available features and saw no options for wifi/updating/or cellular connection.

 

Take a look at my first picture in post #67, I’ll bet those ribs are what your probe is getting caught on.

 

How I read this diagram (I'm going to ignore the right side of the vehicle which has been documented correctly) in the middle of the dash there is one harness for pre 2019 and one after 2019 both shown at the same time. All total there are two connectors going to the two different years "Navigation Antenna Assembly" and SIX various connections into the radio. Of course, I don't believe all six are used for all years.

 

Well, this thread is a DEAD END. See:
Does anyone know where I can find the truck's 3G/LTE module?
Post #19 specifically.

The cell antenna is inside the DCM.

I haven't read through this thread yet:
Disabling DCM telematics transceiver “safety connect” connected services module) | Tacoma World

 

so i guess we have to remove the module, wrap it up like a TV dinner and ground it
is the only way to go?

 

I'll open my DCM up, disconnect the battery, find the antenna and terminate it.

 

Please take a few pics please.