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 #378914  by LUNAT1C
 May 3rd, 2019, 2:47 pm
Reading through all of this (being an engineer, I'm very interested in learning about it, but being a mechanical engineer, much of it flies over my head) has me wondering if it might be possible to get an iDatalink Maestro to work in an LH. In my Jeep, the Maestro serves a dual function of acting as a steering wheel interface to work with my Kenwood radio, as well as pulling data from the Jeep's diagnostic port so the radio can easily display such things as current tire pressure for each individual tire, vehicle speed, G-force, fuel consumption, RPM, oil pressure, trans temperature, 0-60, 1/4 mile time, etc. etc. Some of those bits are comical in a 6000+ lb Wrangler, but some of them I appreciate as I don't need to cycle through the EVIC in the IC to find it.

It would be nice to have some of that data displayed easily in my M as well. Naturally the Maestro does not have the LH cars on its compatibility list. I wonder how much work would be needed, as I'm certain a DRBiii would pull that live data from the diagnostic port.

Just thinking out loud. Not really related to this project since the 8.4 FCA radios don't do that.
 #378925  by 00R/T
 May 4th, 2019, 10:09 am
LUNAT1C wrote:Reading through all of this (being an engineer, I'm very interested in learning about it, but being a mechanical engineer, much of it flies over my head) has me wondering if it might be possible to get an iDatalink Maestro to work in an LH. In my Jeep, the Maestro serves a dual function of acting as a steering wheel interface to work with my Kenwood radio, as well as pulling data from the Jeep's diagnostic port so the radio can easily display such things as current tire pressure for each individual tire, vehicle speed, G-force, fuel consumption, RPM, oil pressure, trans temperature, 0-60, 1/4 mile time, etc. etc. Some of those bits are comical in a 6000+ lb Wrangler, but some of them I appreciate as I don't need to cycle through the EVIC in the IC to find it.

It would be nice to have some of that data displayed easily in my M as well. Naturally the Maestro does not have the LH cars on its compatibility list. I wonder how much work would be needed, as I'm certain a DRBiii would pull that live data from the diagnostic port.

Just thinking out loud. Not really related to this project since the 8.4 FCA radios don't do that.
I’m familiar with the Maestro, but I don’t know the full extent of its interaction on the bus when it comes to the runtime data. If it’s just passively listening to the messages already being sent and parsing them, that should be relatively simple. If it’s sending requests for stuff, that’s a bit trickier. The other concern is that the LH doesn’t send a lot of data like that under normal operation, so it would probably require requests. I’m also not sure what you can request while driving. It’s definitely sometging that can be investigated, though.
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 #378926  by paintballdude05
 May 4th, 2019, 11:11 am
Wow Steve great work! I wish I had the skill and time to do this kind of project, I find BUS interfaces on newer vehicles to be really interesting.
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 #378931  by M-Pressive
 May 4th, 2019, 3:32 pm
Pretty incredible stuff Steve!

Any chance you could get a heated steering wheel to work?
 #378936  by 00R/T
 May 4th, 2019, 7:10 pm
M-Pressive wrote:Pretty incredible stuff Steve!

Any chance you could get a heated steering wheel to work?
Possibly. It’s something I’ve thought about. I’d love to have a wheel thickened and rewrapped and see about putting a heating element in. The only wire at the clockspring that can handle the current is the one for the horn. I don’t know if the internals of the clockspring are sufficient to handle it continuously, though. My thought was that I would then take the wires that are used for the cruise control or the radio switches and use them for a CAN or LIN signal instead. Have a module inside the wheel that handles the horn, all the switches, temp sensor for the heater and the relay to turn it on talk to another module under the dash that interfaces with the rest of the car.

The best way to do it would be to use the wheel and clockspring from a newer car if you could do it mechanically, but then you no longer have the correct airbag. I don’t know if it would throw a code or not, and who knows what would happen in a crash, so that’s a concern.
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 #378937  by 00R/T
 May 4th, 2019, 7:26 pm
I can cross another item off the list. Since I’ll be hiding the ATC head, I need to relocate the temperature sensor and aspirator somewhere that they can still sample interior air. Since the thermistor is currently mounted directly to the ATC head PCB, I decided to switch to the unit used in most of the modern FCA vehicles. It’s all integrated in one unit and designed to be installed away from the controls. I’m planning on making a mounting boss for it (probably 3D printed) and finding somewhere to put it. I’ll cut vent holes in the surface, epoxy the boss over them, and mount the sensor to it. I’ll need something relatively flat with enough space behind it and that is exposed to cabin air. I’d also like it to be somewhat inconspicuous in case the slots I make in the panel for air to flow through don’t come out the best. The typical spot nowadays is in the knee bolster, so I’ll probably use that if there’s enough room behind it.

Unfortunately the new unit uses a 47k thermistor instead of the 10k in the ATC head. It’s a nice, small, epoxy dipped piece that the sensor is designed around. I was able to find comparable 10k ones, but after doing testing at various temperatures I found that the one used in the head has a very unusual temperature curve that didn’t match anything I could find. So, I desoldered it from the head and carefully rebuilt the sensor with it. It didn’t go in perfectly because it was a bit too large and I didn’t have the exact size wire, but after some careful solder work and some hot glue it should be functional.

Thermistor I removed from the sensor:
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Sensor with thermistor from ATC head:
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3D model of my mounting boss design:
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 #379280  by remi
 June 11th, 2019, 3:09 am
Hi Steeve,

I don't know if this will help but anyway... The 1999 or 2000 ATC I have has a custom Motorola MCU, MC68HC05 based. The VFD driver is indeed an OKI chip, a MSM5267B-15 to be accurate. It's a 33 channels driver, although the VFD only uses 25 channels IIRC. I haven't checked if it is relying on the OKI chip to drive the two amber leds on the side of the switches...
Anyway the OKI chip is a basic shift register. The logic analyzer confirmed it's working on 33 bits per word, there's a data line, clock, and a latch. I don't think the "blank" is even used. I have identified the VFD pinout and VFD to OKI wiring but the logic analyzer does't correlate to my findings so... more work required.

I'm stunned by this project, this is great work! Keep it up :)
 #379344  by 00R/T
 June 15th, 2019, 4:55 am
Thanks for the update, Remi. The more we know about the guts of these systems the better!

I apologize for my lack of updates, but it’s due to a lack of progress. The bare PCBs that are going to go into the ATC head arrived a few weeks ago as did the components for them. However, I’ve been really busy with spring chores around the house and just haven’t had the time to sit down with them yet. It’s going to be quite a bit trickier to test this part because the head won’t run without being in the car. Hopefully it works straight away and I won’t have any debugging to do, but I’ve been doing this long enough to know how unlikely that is!