After market stereo

[zoltanb]

Question for audiophiles, would it be possible to install a swi-jack between the crt and the after market radio? It would be great to be able to control the radio from the crt. I finally decided to install a radio under the arm rest and new speakers and an amp in the trunk. Thanks for your help.

[handmedownreatta]

i think daniel did that.

[KDirk]

Daniel's solution was good (and probably the best implemented so far of any posted here) but did not give one full control of an aftermarket stereo via the CRT controls. So far, there is no off the shelf way to achieve that. I've been experimenting with some things, but nothing is an easy, seamless solution.

There are a couple of problems here. First, all the CRT controls for radio and tape are relayed to the CRTC which then converts the touch screen button press to an E&C command. E&C bus is the GM data network in mostly 80's and 90's cars for remote radio modules using separate control heads. In the Reatta, the CRT is the control head, the remote radio module is the silver box in the center console.

Converting E&C data to control aftermarket equipment is very difficult as E&C is a pulse width modulated communications protocol, not a standard serial data line as with most other vehicle data buses. The hardware needed to transmit and receive PWM encoded data is rather specialized and timing critical. There is also the issue of there being no (known to be anyway) documentation for the E&C command set. GM has, intentionally I'm sure, kept that info for themselves.

Further complications arise from the hardware design of the CRT controller. It uses two microprocessors, an 8088 and an 8052 (both old Intel CPUs). The 8052 handles the PWM (E&C) bus but it seems the communications back to the 8088 (which handles the main CRT program and screen display functions) is designed in such a way that an externally sent command does not get reflected back to the CRT. For example, if you have an external device that sent a command to "tune up" or "select FM preset 3" to the remote radio module, it will get that command and act on it, but the CRT will not reflect the change, rather it will continue to show the last station selected by buttons on the touchscreen. So it is not a true bi-directional bus in which the CRT monitors the status of the radio. Rather, it just assumes that what was last selected from the touch screen was acted upon, and so that is what the CRT display shows.

It was probably needless for me to get so technical, but I think this information is useful and should be posted. What would really be needed is a module (from an outfit like PAC or Axxess) that could eavesdrop on the E&C bus to intercept commands, and then convert those to commands that would feed the remote control input on an aftermarket head unit. Simultaneously, it would need to be able to transmit E&C commands back to the stock system for things to remain in sync, or things would get very confused. I am not aware of any such module offered by the usual suspects, and that also includes Metra.

So, for now, there is no fool-proof way to use the CRT to gain full control of an outboard head unit. Given the obsolescence of the E&C bus, I doubt anyone will develop such an interface now. If it was going to be done, it would have happened 15+ years ago when there were still new a lot of new cars being made that utilized the E&C bus.

KDirk

[padgett]

Personally I am fascinated by what you can do with a 7" tablet and OBD-II (why I have not been here much lately). AFAIAC all the Reatta really needs is an Aux jack and a place to put the tablet, it already has all of the diagnostics built in. I just wish they hadn't dumped the CRT when the 'vert came out.

[KDirk]

Padgett,

That is a nice setup. It is too bad there is really no OBD-I support in terms of applications for these. I know the diagnostics are built in on the Reatta, but many programs offer the ability to read OBD-II data to use the tablet (or notebook) as an auxiliary instrument panel with additional (or more detailed) engine data readouts & gauges. Even some aftermarket navi head units offer this functionality now for OBD-II. Wish the same were possible with OBD-1 systems, but really only the handful of PC based tuner software programs offer anything close (are not really made for this purpose), and will not run on a tablet.

The thing I would like most is a way to fully integrate the CRT controls such that they could have command of an outboard aftermarket stereo rig. I am working towards that objective, but it will still be a kludge unless I magically become a master of 8088 AND 8052 machine code and entirely rewrite the CRTC firmware (not likely to say the least). No, this level of integration isn't really necessary, but then I want a lot of things that aren't really necessary.

KDirk

[D-a-n-i-e-l]

Question for audiophiles, would it be possible to install a swi-jack between the crt and the after market radio? It would be great to be able to control the radio from the crt. I finally decided to install a radio under the arm rest and new speakers and an amp in the trunk. Thanks for your help.

Yes you can do it. it is not too hard. you have to cross ref for wiring, but most controls can be used, just be sure to get a programable one. I have not done it yet but if a gut wanted to he could get the kenwood KOS-v's to run off the TCC and not have to use a remote or Kenwood touch screen. It would be a nice touch and not very intrusive to the tcc.

[zoltanb]

Thanks for the info, I hope you guys can come up with a workable solution. Thank You for your efforts.

[handmedownreatta]

there were many gm cars with compatible radio modules.mine is from a 94 regal as i recall.i wonder if any gm cars came with a better radio that the radio module would work with our cars?

[KDirk]

There were a number of other remote radio modules that can be used in the Reatta. Some omitted the graphic equalizer and substituted bass/treble controls in it's place. Some BOSE system RIM modules can also be used, but these are un-amplified and require an additional outboard amp to be useful. These were installed mostly in mid 1990's Cadillacs with the optional up-level Bose/Delco Gold systems. I believe these typically have tone controls (bass/treble) but no balance (L-R) control. Both of these variations will work with the Reatta CRT setup, as the CRTC contains programming to recognize at least three different types of RIM modules. Keep in mind that some CRT equipped Rivieras had the radio without the EQ, and in 86/87 Rivi's even the outboard tape deck was optional.

I think the better solution at this point (if just wanting better sound) is to mod the Reatta RIM module with pre-outs and use a good outboard amplifier to run the speakers, abandoning the amp built into the radio. It may have been pretty decent in 1988, but it falls short in both power and fidelity when compared to current auto sound gear. By doing this, you retain the EQ, if that is important to you. It also takes the original amp circuit out of the equation, and along with it the higher noise and distortion of the stock amp. Done right, it should also reduce or eliminate the effects of the bass roll-off "programmed" into the stock amp contained within the radio module. This still leaves you with full CRT control of the stock tuner, volume/balance/fader, EQ, and tape input if still being used. Other mods for using more modern auxiliary input sources have been discussed here in detail in the past. A search of the forum should yield some interesting reading.

KDirk

[handmedownreatta]

actually im pretty happy with my satelite radio fed in through the tape player input.it sounds good to me too.it does irritate me that i have to go to the radio page and hit play everytime i crank the car.i drove a car with hd radio for a week and liked the song information.it would be awesome if someone could figure out how to make an aftermarket hd radio module work with the reatta crt.

[padgett]

Two color CRT is not the way I'd want to go. Personally I'd remote a Windows SBC to use a panel-touchscream (Windows 8 is designed for this). Biggest problem is that the CRT is 4x3 and modern displays are 16x9. moates.org has ODB-1 adapters and software just is a lot easier with a 7" tablet and Torque or Touchscan (OBD-II) & a Bluetooth adapter.

What I am working on involves making a car a mobile hotspot an not only having normal stuff like audio and instruments but also full web access for sat-nav and entertainment plus built in unlimited telephony (not cell, VOIP). Carmakers are getting closer (Bing in Toyotas) but will probably never want the owner/driver to know as much as possible with OBD.

Technophreaks will note that Bing is Android based.

Everything is possible today (see all-in-one plans like Smart-Talk) just lacks integration.