S17 Crown networking and entertainment system discoveries (AVC-LAN and BEAN perhaps?)

[Arbition]

Hey all,
So for the last two days I've been poking around my car in the areas related to the audio and video systems in order to try and work out how to control the aircon from something other than the centre panel. I have the video screen version, meaning some of that control is touch based. Very bad if you're considering a complete replacement of the centre screen for something else. Along the way I have found out some interesting things related to the network of stuff in the car. So far, the components I have come across are: The multi-screen, headunit, DVD navigation system and TV tuner.

Probably the thing of most interest to people is the AUX in, so I'll start with that. I first heard about this when I was reading http://forum.jdmstyletuning.com/show...thlete-V/page2 (post #19). However I was unable to find the input plug that was talked about. The last thing I found was the tuner, using this as a clue http://www.jp-carparts.com/toyota/pa...3&part=2066538. I took apart the TV tuner and started poking around with a multimeter. I found a couple of audio OP amps, which was a little puzzling, especially because I found that they were using the blue plug as a source, rather than as the output. I also eventually traced one of the lines going to the large control chip. It was only after this that it dawned on me that I should check whether this is as described. I started by checking that TV functionality worked without the blue plug. It did. Then I checked the jdm style tuning thread for colours in use. They mostly matched. Finally I bridged the white with green stripe to a ground. Bingo, on the Channel select screen came up the VIDEO option (which again is different to as described in that thread). This also leads me to believe that there were multiple versions of this system, which is also supported by the many different version of components that were used throughout the lifetime of the S17 crown (as per the jp-carparts.com link).



The plug on the left is presumably the antenna, because it was separate from the loom with the other three. The plug on the right seems to be the R4 audio bus connector, referenced in http://elinux.org/images/e/ed/Avc-lan.pdf. This means that in all likelyhood the 5 pin 1 row connector is the video output. In the wagon version, the tuner is found under the right hand side false floor storage compartment.



I also notice a small amount of water is collected below it and the yellow stuff is moist in some areas, which is a little worrying.

Next up, I found that the DVD navigation system is rather optional to the operation of the rest of the system (except perhaps for GPS synchronising the clock, I haven't had the car powered for long enough to be sure of this). I did find that in removing it, the default screen often becomes a blank and unlit screen, and its buttons don't cause any response whatsoever, so it seems that the navigation unit is completely responsible for its own operation. This makes me wonder if it is thus possible to replace it with something else and utilise full touch capability with it (something the AUX does not have). Not my plan, but someone else might want to have a go. In the place of the nav computer, I put this for sizing:



That is nearly a fully fledged computer there (ITX form factor). Well, I plan to completely replace the centre screen as I implied earlier. This means I'm going to have to do something about air conditioning control. I started swapping plugs in and out of the headunit and the display. It seems the minimum needed to operate the aircon controls is the two outermost plugs on the display and the white plug on the headunit. Once I found out about the R4 plug referenced in the elinux pdf, I was extremely confused as to why it was necessary at all. It was apparent that the white plug alone does not supply power to it. I eventually tried putting a 68 ohm resistor between the data lines on the plug.



This worked. It dawned on me the reason this was needed was as a terminator. The elinux pdf implies that the resistance of the terminator should be higher, but I just copied what I found on the deck for that job. The cable shown here was part of an interceptor loom to connect the ETC toll system, something which I don't think we'll be using in Australia. It too used the twisted pair system. Now there is a problem. The elinux pdf is for AVC-LAN, intended for control of the entertainment system. According to this http://share.qclt.com/%E4%B8%B0%E7%9.../be/multi2.pdf, this http://www.toymods.org.au/forums/tec...iplex-etc.html and the elinux pdf, Aircon is controlled by the BEAN bus. The bean bus is a single wire protocol, but clearly what has been causing this issue is a twisted pair bus of some kind, which I would say is most likely AVC-LAN, mostly because of the R4 connector found on both the headunit and the tuner. This implies that the display is actually issuing AC commands via AVC-LAN and something else is converting it to BEAN (or something entirely different).

Edit: Found the amplifier (looking at the headunit didn't show much in the way of amplification, so I wasn't surprised) above the passenger side kickboard near the chassis. It is easily distinguished by its large heatsink fins (though they may not be easily visible without removing the glovebox). Disconnecting this had the same effect of making the aircon and audio systems unusable. I accidentally plugged it back in while live, and noticed that the aircon screen repopulated itself, albeit, with a different button layout. Switching screens and then back to the aircon screen restored the layout. This makes me think that this screen may be somewhat dynamic (ie the multi display determines what controls it should show at runtime, rather than being pre-programmed).

In terms of something which does airconditioning control, the most promising thing I have found is this http://lexus.popformance.com/ but I know rather little about the Lexus SC300 SC400 and Soarer.

Another miscellaneous discovery I found is in the BEM, which I took apart once I worked out that the sound of the door chime could not have been coming through the speakers. The chime being so loud that when I put my ear around, I couldn't adequately determine the exact source. Note the large piezo buzzer. Taking this apart any further would have been risky, due to the soldered and cheap ribbon in use between boards.




Finally, some more nitty gritty details I recorded https://docs.google.com/document/d/1...it?usp=sharing where I discover just how common the twisted pair system is.

[Arbition]

I might add, I'd like to know how systems with the two row monochrome LCD system does it.

[egamirrorim]

Subscribed cuz I'm expecting an JZS171 Wagon soon.

Were you able to see any identifying marks on the amplifier?

[Arbition]

Sorry I did get photos, just that it was late and I didn't feel like processing them. Here:

[smash palace]

Hi Guys
I finally got my Crown wagon from compliance ( 4 months)
and have started modding ,so far I have fitted a viper alarm and have found the aux connecter, its under the centre console arm rest.
Next I will be adding a Ipod interface and have a go at using a different amp.

Stuart

[1jzmonsta]

Sorry to bring this back from the dead but can someone tell me do all the crown models have an amplifier as i can’t seem to find mine. I’ve looked behind the glovebox to the chassis side and there is nothing really there that looks like an amplifier