Simpler solution for disabling the DCM telematics - Silencing Antennas

If you plug in the antenna cables one by one into the head the unit GPS antenna is the only one will work. That's the only one going to the antenna

 

I have pulled the DCM module and removed the SIM card. I have an inoperable DCM module.

Your suggestion of trying different antenna connections to see what would happen occurred to me some time ago, but since I have an inoperable unit and no way to see GPS or Telephone reception even if my unit was operatable, I shelved it; another idea came to mind after you mentioned it so I took another tack. The information below may be of GREAT interest to others who may wish to reuse the DCM GPS antenna for another use and "Possibly" the Easiest DCM deactivation ever. Needs testing.

My tack was to use TechStream error codes which it turns out the DCM module does generate. Previously I had stated I did not see any error codes; in fact I did not see the module from within TechStream at all because I had no power to the unit for it to send any data to TechStream - I need to stop working on so many projects at the same time! I have since reconnected all cables and replaced the DCM fuse, so the unit is powered and operates in all ways (Microphone, Left speakers still function), just without the SIM.

The DCM does detect if the individual antennas are present or not, if the antennas are not present it brings up a code saying just which one is "Open". I eliminated two antennas at a time and found the Top antenna plug on the DCM module is the Telephone Sub Antenna, while the Middle antenna plug is the GPS Antenna, and the Bottom antenna plug is the Telephone Main Antenna. The Titles of these antennas come from the original post in this thread.

::::NOW for the kicker of this whole thread::::

It may be all that is needed to deactivate the DCM is to disconnect the antennas with "no" termination. My intuition says that the DCM detects disconnected antennas so it does not self-destruct trying to transmit into an unterminated output. It may turn out the OP @altitude-nerd was too good at what he was doing, and the trouble started because he knew GOOD engineering practice of terminating Radio Frequency outputs; what may be needed is BAD technician practice the DCM detects and deactivates itself.

The pertinent error codes:
B153713 "Telephone Sub Antenna Circuit Open"
B15C113 "GNSS Antenna Circuit Open" - [GNSS is inclusive of GPS and other world satellite systems.]
B15CB13 "Telephone Main Antenna Circuit Open"
also
B15CC49 Backup Battery Internal Electronics Failure - [I have my DCM battery disconnected.]

Errors from within TechStream also revealed the DCM tries to contact Toyota every 2 hours, as other errors of "no" communications were present. I made no note of these error codes.

All Antenna codes appeared within TechStream within 5-10 seconds of disconnecting an antenna.

The disconnection of the Telephone antennas from the DCM module still needs to be "tested" to see if it does indeed deactivate the DCM from transmitting to Toyota. @Disgruntled Scientist I believe would be a great candidate for this test.

Another test would be to Short out the Antenna plugs and see if the module sends a "Shorted Antenna Circuit" code to TechStream. This "Shorting" would be even more imperative that the DCM deactivate itself to avoid self-destruction due to a transmission.

Not exactly Toyota codes, but close enough:
Lexus NX - Diagnostic Trouble Code Chart - Safety Connect System (lexunx.com)

Even with all this I do not know which antenna is the Main and which is the Sub Telephone antenna, i.e. roof or dash.

I would like to posit that the dual Telephone antennas are for redundancy in case of an accident that destroys the Shark fin on the roof during a rollover accident. The underside dash antenna may remain intact in such an accident.

 

After some more digging into the white papers, it looks like it starts collecting data from the very beginning and the data can not be erased. I would love to dump that BGA chip! Not sure if I still have a BGA programmer or not, anyone else happen to have the ability to dump BGA's?

 

Anyone know where the Bluetooth radio is in these trucks? I completely removed every single A/V component and OEM wire from my truck. Head unit is gone, Even down to the speaker wires are even gone. The DCM is out of the truck in pieces on the bench in my shop. I have NO OEM factory wiring harnesses connected at all, but "Tacoma" Bluetooth is still being broadcasted? If you try to connect to it, it won't, but if the BT radio isn't in the OEM head unit or the DCM where is the BT radio located???

 

I don't think there is an external antenna you can hook up to your phone for better reception. ????

Where is the under dash antenna?

 

I'm stumped. Unless the phone keeps some memory and just needs to be power cycled. I've seen that happen with Wi-Fi. Don't use much Bluetooth.

Had no idea what a BGA chip was, learned another acronym. The Kyocera chip certainly qualifies. Finally found an old schematic of the Telematrix unit and the three-pin metal connector is indeed a USB connection to the radio. Attached.

The other antenna is just below the underside of the dash between the radio and the instrument panel. Two coax cables enter the rear of it; perhaps in your removal of everything you already took it out too.

 

Wait what? That does not seem to line up with the rest of this thread. People are saying it kills the right hand tweeter and are specifically doing electrical wiring tweaks to recover the right tweeter.

If pulling the DCM fuse simply kills the connection and the mic but nothing else I am going to buy a 2024 Tacoma. Those are the two things I would want to disable anyways

 

On an iPhone, pull up the Bluetooth list, tap/select the circled “i”of the Tacoma signal. and you should be able to “forget this device”.

 

Fujitsu-Ten 726e head unit

 

So the GPS plug that goes into the back of the head unit is not in the shark fin?

 

I just verified, it is the right side not the left side; both the right tweeter and right front door speaker are affected or so I believe, although I can only hear the right door speaker with my hearing. If you remove the module or unplug the speaker plug from the module then you lose the speakers. If you remove the DCM fuse only - the speaker connections are intact and the only thing you do not have is the microphone in the headliner. Sorry for the confusion, when I was doing my work I had the front dash pretty much apart and I did not have my left speakers either - but that was another issue. My hearing is not great and I do not hear the tweeters, either left or right, even with the BASS and MIDrange adjusted all the way down with the TREBLE up all the way up I cannot detect that either left or right are working.

Before buying verify for yourself by removing the DCM fuse, the fuse legend is on the inside the cover of the engine fuse box and the fuse puller is also attached to the inside cover. I cannot state if the 4th generation 2024 is the same as the 2020-2023s. First turn on the radio, use the fader controls and alternatively adjust the fader right and left to see that everything is working. Then remove the fuse on the 2024 and reverify that the speakers work.

My vehicle is a 2021 Access Cab Off Road V6 AT.

 

The chip in the green box holds all the secrets. That is the BGA that needs to be dumped. It's a Micron, but I can't find a white paper on it. Anyone have and extra junk unit we can take apart? Need to remove the Kyocera daughter board from the Toyota PCB. These units have no value, they can not be used in another vehicle, ever. So if you know someone with a junk yard and can pic one up for like $20 let me know.

 

Not according to the drawing in Post #42 of this thread. In that post *3 shows the location of the dash antenna array, while *1 is somehow not shown in the drawing, I have seen in other drawings that *1 refers to the roof antenna array. This assumes the roof antenna array is the primary for the DCM telephone and DCM GPS, while the Dash antenna array is the GPS for the radio/navigation and the Sub DCM telephone antenna.

 

I think total removal or removal of the UICC chip is the only way to make it not be able to call home.
My biggest concern with this box is it records data no matter what. they state, so-say (here's where my hackers days come in) that data can not be erased. So even disabling the call home feature still records everything you do. GPS data, etc, as long as it can get a signal.

I'm for sure going to call in a complaint to Toyota. Also can't wait till next time I go to the dealership and they can't read it

 

Here is a picture of that chip from my DCM module.

Don’t know for sure, I've not been concerned with the radio.

All that is for sure on my vehicle is that three coax leave the DCM. Then one of the three coax heads towards the radio area, I presume this is one of the telephone antennas as there is no reason to have two telephone antennas collocated. My presumption is also based upon that the drawings saying the under-dash antenna assembly has Telephone & GPS.

A total of four coax go up to the roof. The two from the DCM, GPS & Telephone and two that come from the radio area, again a presumption of AM/FM & Satellite radio.

At my radio area there are three coax that plug into the back of the radio. AM/FM, Satellite radio and I presume a GPS. This GPS I again presume goes to the under-dash antenna assembly and is used for Navigation with the extra telephone antenna from the DCM. Don't have schematics for this, just investigative time.

I had to draw this out on paper to see the picture.

 

Wait, if you pull the DCM fuse you don't lose the speakers, but if you remove the DCM you do? Man this just shows I really do not understand electronics. If the DCM is getting no power, and the speakers run through that, how are they powered?

Doesn't pulling the DCM fuse result in the infotainment screen showing no signal, and information on the car no longer being updated in the Toyota app?

 

The radio feeds the audio into the DCM, within the DCM there is a DPDT relay that is normally unpowered or unenergized, in this unenergized state the audio is free to travel from the radio direct to the speakers (via the DCM relay). Only when the DCM commandeers the speakers away from the radio is the relay energized and disconnects the radio from the speakers. See the DPDT diagram at:
File:Relay symbols.svg - Wikipedia

The speakers are connected to the C1/C2, the Radio is connected to B1/B2, while the DCM audio is connected to A1/A2. With the DPDT relay unenergized the flow is from the Radio B1/B2 to the Speakers C1/C2. Remove the DCM and you remove the relay making all these connections. Thus no DCM, no audio to the speakers without installing speaker jumpers at the connector replacing the connections normally made by the unenergized relay.

Another way to look at this is the water hose analogy - If you join two hoses together to reach the far corner of your yard you are fine until a neighbor dog comes by and chews the hose in two. In this case the dog chews the connection between the two hose sections.

 

Found this picture of the Shark Fin:

in this thread:
Broken Antenna on 2020 SR | Tacoma World

 

You say you cannot find a data sheet on the Micron. It seems to be protected or obsolete on Micron's website.

Try this page to get the real number:
FBGA & part decoder | Micron Technology Inc.

Then paste the number that comes up into their main page search:
Search results | Micron Technology Inc.

This info will tell you a little bit about the chip basics.

I would not understand anything if I went any further in the inquiry of the chip. It may be registration is needed on their site to get the Data Sheet.

This site might be of some help too:
JY990 [VFBGA162] - Micron | Elnec

Oh, this too; ESPECIALLY This.
Part Detail | Micron Technology Inc.

 

I opted out of the Toyota services and pulled the DCM fuse. There are rare times I could use the mic, primarily on long road trips. If I don't care about local data collection in the DCM for the short time it would be on so I can use the mic, would simply adding a switched fuse bypass and running it into the cab work?

$18 uxcell 1 Set 133.5cm 52.56" Universal Automotive Switched Fuse Bypass Kit Fuse Bypass Switch

https://www.amazon.com/dp/B0CJJP33X2?ref=ppx_yo2ov_dt_b_product_details

The only downside I can see is putting a hole in the fuse box cover (should not be hard to seal once the harness is run) and finding a place to pull the harness through the firewall. Any thoughts on this route as it seems easier than rewiring the mic?