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Discussion Starter #1 (Edited)
I'm working on trying to replicate the install of the official cell phone accessory in my 1993 3000gt VR4, but I need help with some details about how the phone is installed, what parts I need, etc.

Yes, I know it's an analog cell phone and I won't be able to actually use it. It's mostly for show/novelty, and I plan to try modifying the handset to work as a bluetooth headset.

UPDATE: I found wiring and connector diagrams for the factory phone. See this post and posts afterward.

UPDATE: I am looking for these hands-free parts (see this post)
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--- ORIGINAL POST BELOW HERE ---

Here's what I know so far...

I've had some people insist that there was no official cell phone accessory option, no standard way of installing them in the car, etc.. So I will start with the evidence of an official accessory existing. The original sales brochure for the car mentions a cell phone option, and that "complete pre-wiring" is already provided:

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The official 1993 Mitsubishi accessories brochure has some details about the phone in a section dedicated to the 3000gt:

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So I know it's a DiamondTel Model 92 cell phone, and there are even hands-free features and speed dial controls mounted to the steering column when installed.

Getting the phone itself is fairly easy. There were a few ebay auctions, and I picked one up that looks to be in good condition (not delivered yet) that includes:
  • The portable phone base (big box with battery, antenna, etc).
  • The handset.
  • Power adapter for a 12v car outlet.
  • Leather carrying bag
  • Instruction manual
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Bare minimum, I need to get the appropriate handset cradle and mounting bracket to install it on the side of the center console. Someone shared a screenshot of an old craigslist ad for the cell phone parts out of a 3000gt, so I at least know that the bracket I'm looking for looks like this:

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It also looks like there's a junction box with wiring that is used to hard-wire the handset cradle into the car's power and antenna wiring.

UPDATE: That gray box is the "Hands free controller" that integrates the phone base station with hands-free controls, the phone handset, and the car audio system (see this post).

If anyone can provide additional info, I would very much appreciate it:
  • What kind of "pre-wiring" exists in the car and where is it?
  • What are all the parts I would need to replicate a full install, and how are the parts installed?
    • Please share pictures if you have this phone installed in your car!
    • For example, even if I got my hands on the junction box from the above photo, I have no idea where to put it.
    • I haven't even seen what the steering column auto-dial controls look like yet.
  • Are there any part numbers for the install kit or individual special parts?
  • Are there any technical documents, diagrams, or installation instruction documents for the install kit?
    • I've already searched through the service manuals and technical documents available on 3sx's website and couldn't find anything.
  • Does anyone have any of these parts collecting dust? I'm interested in buying.
Thanks!
 

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I recall taking that wiring out at some point. If I recall correctly, it came in under the carpet on the pass. side of the console...but it's been a long time ago. It'll be obvious when you find it.
Cool project, I like it.
 

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Discussion Starter #3
Parts guy at the local Mitsubishi dealership couldn't find any info in any catalogs he has access to. He even dusted off their microfiche machine and ordered a new bulb for it so he could search through archives.

I've now sent messages to both Mitsubishi Motors and Mitsubishi Electric (division that made the cell phone) asking for assistance. I'm hoping someone will have the curiosity and willingness to dig through old archived info to help me out.
 

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After having many of these cars apart - sometimes down to the bare floorboard - I can say with absolute certainty there is no pre-wiring for the cell phone. And the Mitsu cell phone did not use the AM/FM antenna. It used a glass mount antenna that was added. My best guess is that the accessory kit might have included a T-harness that plugged in behind the radio or at the ignition switch to get power. That's just speculation. But if you're going to make it bluetooth, all you really need is ignition and ground to power up the light bulbs and the bluetooth handset circuitry that you bury inside of it. That should be easy enough. Ignition is blue behind the radio. Ground it to metal in the console. Would love to see pics when you finish it.
 

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Proper Radwood shenanigans. I would love to have the cellphone as just a 90's nostalgia gimmick, working or not...

I remember some friends bought a 91 Eclipse GSX Way back when that came with the optional Mitsubishi Car Cellphone... I can't even begin to understand how incredibly rare option must be on those cars, much more common on the 3/S I'm sure but I can't say I've ever come across one.
 

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Discussion Starter #6 (Edited)
I recall taking that wiring out at some point. If I recall correctly, it came in under the carpet on the pass. side of the console..
Thanks for the tip.

After having many of these cars apart - sometimes down to the bare floorboard - I can say with absolute certainty there is no pre-wiring for the cell phone.
...
My best guess is that the accessory kit might have included a T-harness...
I wonder if the sales brochure description of "complete pre-wiring is already provided" is not talking about the car, but about custom wiring and junction/amplifier box provided provided with the accessory kit. Either way, I'm guessing it's designed as mostly plug-n-play rather than requiring wire splicing.

And the Mitsu cell phone did not use the AM/FM antenna. It used a glass mount antenna that was added.
Yeah; there's no need for me to add that antenna to my car. I gotta draw the line somewhere :)

But if you're going to make it bluetooth, all you really need is ignition and ground to power up the light bulbs and the bluetooth handset circuitry that you bury inside of it.
Right. Bare minimum, I want to have the outward appearance of a complete/correct install with the handset cradle mounted to the center console with the correct bracket and the cradle wired to power so that the handset turns on. If I can get my hands on some of the other "hidden" parts (correct wiring, junction box, etc) so that I can get a plug-n-play power supply to the cradle, then that's a bonus for simplicity and completeness.

Next step is a basic integration bluetooth hands-free device electronics into the handset's microphone and speaker, and a few buttons as necessary to answer/end calls, etc.

The ultimate goal would probably require some custom microcontroller programming and electronics to support more complete functionality of the handset so that I could dial a number into the handset, see that number appear on the screen, then send the call, maybe even have access to the contact list on my phone, etc.. At that point, I would probably be ripping out all of the electronics/screen of the handset and putting in a more modern LCD display that I can control. I'll probably have to get a second handset to tinker with. I predict a lot of research into bluetooth profiles and bluetooth chips in my future.

(UPDATE: I have an even better idea for adapting to bluetooth, described in this post)

Would love to see pics when you finish it.
If I get enough parts to start doing something, I'll start another thread and report progress.

Proper Radwood shenanigans.
Ha! I've actually thought about how this might make it worthwhile to take my car to Radwood. I might also have to invest in some era-appropriate "successful businessman" attire to match my fancy expensive car and portable phone.

I could even carry the bag phone around with me for full effect.
 

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When I bought my car it had the external cell phone antenna and some extra cables to the trunk (that werent for the CD changer as it had that too). I bought the car from my neighbor who was the original owner so Im wondering if he removed the phone and associated extra parts at some point. I can try to get in touch with him to find out, and see if he might even still have them if he did remove it.
 

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subbing for updates! I had also wanted a dealer installed phone for "novelty". please post more pics and updates if you get it installed! :)
 

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Discussion Starter #13 (Edited)
First set of parts acquired:
  • DiamondTel Model 92 Handset.
  • Transceiver.
  • Transportable cover (contains battery and phone cradle that mounts onto transceiver).
  • Removable antenna.
  • Cigarette lighter adapter.
  • Fancy carrying bag.
  • Instruction manual.
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Above: battery and "transportable cover" separated from the transceiver (right).
 

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Discussion Starter #14 (Edited)
First challenge was to make the handset operational. The battery was dead, so I first plugged the cigarette lighter adapter in a car to test. I was able to turn the handset on, but it simply displayed "CHECK 3" on the screen and did not respond to any button presses.

Luckily, the instruction manual contains setup/programming instructions:

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I was able to follow these instructions to give the phone my phone number, and enter random values for all the cell phone carrier data (doesn't matter, since all analog cell networks in the US were shut down 11 years ago).

The handset now powers on and is fully "functional", although is has "no service". I'm able to pretend to try to make phone calls, adjust all settings, add phone numbers and names to the address book, etc.. The fun part is that if I use the option to display the phone's own number, it displays the phone number I entered during setup (my actual cell number).

Next I worked on reviving the old NiCd battery. I don't have the A/C adapter, and I didn't want to leave it sitting in a car with the ignition on for several hours, so I got creative with a battery charger:


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The battery is technically 2 separate 6v batteries with 1400 mAh capacity each. The phone runs on 12v, so I assume the two pairs of terminals on the battery pack are connected up in series inside the base. I had to charge each pair of terminals separately. I'll probably do a couple full discharge/charge cycles to try to recondition the battery, but it seems to be working well so far.
 

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Discussion Starter #15
Here's some pages from the instruction manual about different ways to install the phone in a car. What's still not clear to me is if there was any particular "official" way that this would be installed by a dealer into a 3000gt, and if there were any special parts for installing into a 3000gt.

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Interesting note here: if the power cable is wired into the horn relay of the car, you can setup the phone to honk the horn if the phone rings while the ignition is off (so that you can run back to your parked car to answer the phone).

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I have seen a picture of the transceiver mounted in the trunk of a 3000gt like one of the above suggestions:

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Looks like the transceiver mounting bracket is bolted to the plastic cargo tray in the trunk. However: is this an "official" dealer install, or is this just a normal after-market install? This picture is consistent with a suggested installation from the instructions, and also with the picture from this post by twinblown.
 

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Discussion Starter #16
And on the topic of how to make the handset actually useful for making/receiving calls...

The approach I'm leaning toward now is to NOT modify the handset itself to be a hands-free bluetooth device, because it would involve completely losing/replacing all the interesting original functionality of the phone itself.

My new plan is to leave the phone itself intact, but intercept the signals to/from the antenna and emulate communications with an old analog cellular base station. I basically need to build a device that pretends to be a cellular network station, but forwards/translates commands and audio signals between the phone and a bluetooth chip using the Hands-Free Profile (HFP).

The end result would be that the phone believes that it is really connected to a cellular network. All features of the phone would work normally. Outgoing calls would be routed to my modern cell phone via bluetooth, and incoming calls to my modern phone would cause this old phone to ring normally.

I found a somewhat similar project that emulates old analog cellular base stations, but complete with radio transmitters/receivers. I'll be studying this project carefully for inspiration: http://osmocom-analog.eversberg.eu/

Here's an intro (from the same project) to how the "AMPS" cellular system in the US works: http://osmocom-analog.eversberg.eu/docs/amps.html
 

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Discussion Starter #17 (Edited)
Pro tip about programming the DiamondTel Model 92 handset: The instructions in the manual for entering programming mode (power on, hold "clear", press 1951426, release "clear") only works up to 3 times. The instructions cryptically say "(3 times only)", and I didn't understand how to interpret this until after I had programmed the phone 3 times and could no longer program it. After saving changes 3 times ever (including previous attempts to program for a previous owner), this code will no longer enter programming mode.

I think I got lucky with my phone and had all 3 programming attempts available because the phone was in an error state (displaying "CHECK 3") when I received it, so it had probably defaulted back to initial factory settings due to spending years without power.

When you are locked out of programming the phone due to the 3x limit, then you must use a different numeric code (the "reset code"): power on, hold "clear", press 8291112, release "clear".

I have confirmed that this alternative "reset" code always works, regardless of whether programming has been performed 3 times since the last reset. So I would recommend always using the "reset code" (8291112) rather than the standard programming code (1951426).

I found this information on this web page (appears to be a collection of technical details about many phones): T E X T F I L E S
(see the file with description "CELL: Diamondtel (Mitsubishi) MESA 52 and 55", which has details for more phones, including the 92).

Fun Fact: apparently the "DiamondTel Model 92" is also known as the "DiamondTel Mesa 92".

Excerpt from that file about the Model/Mesa 92:

Code:
-------------------------------------------------------------------------------
                 DIAMONDTEL MESA 92 transportable/portable
-------------------------------------------------------------------------------
                NAM Type:  EEPROM
            Manufacturer:  Mitsubishi
              Programmer:  Handset
          ESN Prefix DEC:  134
                     HEX:  86
ESN, S/N Match Required:  No
        Stamped Model # :  1st 2 digits of serial # are 92
    Programmable Handset:  Yes
      Available Channels:  832

    Programming Sequence:  Power On
                           Depress and hold END while inputting 1951426 or
                            8291112 (if phone has been programmed 3x)
                            enter within 10 seconds
                           Enter information for each step then press SEND
                            to increment
                           Press END to write NAM information

                        # of digits
             Dual Number:  1    0 (1 number) or 1 (2 numbers) + SEND
           Mobile Number: 10    XXX-XXX-XXXX + SEND
        System ID Format:  5    XXXXX + SEND
        Local Use Option:  1    1 + SEND
              MIN Option:  1    1 + SEND
  Initial Paging Channel:  4    0333 or 0334 + SEND
   Access Overload Class:  2    XX + SEND
         Group ID Format:  2    XX + SEND
         Timer increment:  1    0 + SEND
(if Dual Number was 0 then skip 2nd programming sequence)
         2 Mobile Number:  10   XXX-XXX-XXXX + SEND
      2 System ID Format:  5    XXXXX + SEND
      2 Local Use Option:  1    1 + SEND
            2 MIN Option:  1    1 + SEND
2 Initial Paging Channel:  4    0333 or 0334 + SEND
2 Access Overload Class:  2    XX + SEND
       2 Group ID Format:  2    XX + SEND
       2 Timer increment:  1    0 + SEND
           Security Code:  4    XXXX + SEND
                     VOX:  1    (0 or 1) + SEND
            Roam Inhibit:  1    (0 or 1) + SEND
          Continuous Tone:  1    (0 or 1) + SEND
      Disable Cumulative:  1    (0 or 1) + SEND
  Disable ignition sense:  1    (0 or 1) + SEND
   Disable own # display:  1    (0 or 1) + SEND
             SID Lockout:  1    (0 or 1) + SEND
            Dual Handset:  1    (0 or 1) + SEND
             RJ11 Option:  1    (0 or 1) + SEND

Press END to exit Program mode.

         New Unlock Code:  FCN + 7 + 4-digit security
                            code (NAM) + new 3-digit unlock code
           System Select:  FCN + 1 + x
                                 X=0  AB or BA Standard
                                 X=1  BA or AB Alternate
                                 X=2  Home
                                 X=3  Pref only
                                 X=4  Non-Pref only

Press CLR to exit.
 

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Discussion Starter #18
Found some more info that confirms my suspicion about why I had 3 programming attempts available. The handset stores its settings in EEPROM, which generally does not require constant power supply to retain its data. But data in these chips does decay over time due to imperfect insulation in the chips, crazy "quantum tunneling" where electrons can randomly go somewhere else, etc.

The wikipedia page about data degredation says this:
Solid-state media, such as EPROMs, flash memory and other solid-state drives, store data using electrical charges, which can slowly leak away due to imperfect insulation. The chip itself is not affected by this, so reprogramming it once per decade or so prevents decay.
Most likely, my phone had been without power for 10+ years and the EEPROM data became corrupt. The phone probably detected the corrupt data upon power up and triggered the "CHECK 3" error code. Upon entering programming mode, the phone likely re-initialized its EEPROM memory to recover from the corrupt data and start fresh.
 

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And on the topic of how to make the handset actually useful for making/receiving calls...

The approach I'm leaning toward now is to NOT modify the handset itself to be a hands-free bluetooth device, because it would involve completely losing/replacing all the interesting original functionality of the phone itself.

My new plan is to leave the phone itself intact, but intercept the signals to/from the antenna and emulate communications with an old analog cellular base station. I basically need to build a device that pretends to be a cellular network station, but forwards/translates commands and audio signals between the phone and a bluetooth chip using the Hands-Free Profile (HFP).

The end result would be that the phone believes that it is really connected to a cellular network. All features of the phone would work normally. Outgoing calls would be routed to my modern cell phone via bluetooth, and incoming calls to my modern phone would cause this old phone to ring normally.

I found a somewhat similar project that emulates old analog cellular base stations, but complete with radio transmitters/receivers. I'll be studying this project carefully for inspiration: http://osmocom-analog.eversberg.eu/

Here's an intro (from the same project) to how the "AMPS" cellular system in the US works: http://osmocom-analog.eversberg.eu/docs/amps.html
I guess you don't need to hook up the old analog antenna because the call is actually being placed via your smartphone? or are you putting in the old analog antenna anyway?
 

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Discussion Starter #20
Correct. I would be intercepting the signal at some point before it reaches the antenna to process it and convert it to work as a bluetooth hands-free device. If I added the analog antenna to the car, it would be only for completeness of appearance. I don't think I care to take it that far. I care more about the appearance of the handset installation in the car.
 
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