As I recently installed the GVIF interface sans HKS Camp2 and I don't use the navigation system other than access to back up camera and gauges, I find myself questioning what would happen if I bypassed the nav unit's fiber optic cable altogether and just installed a loop?

Has anyone tried this? In theory, when I pressed the Nav button on the TSD, would my media box just display instead?

There isn't enough information in the wiring diagram, but from the electrical training guide, there is no interface with the canbus network, just GVIF and MOST.

Does anyone have any spare FO cable they could test this or send me?

 

FO cable is inexpensive. Will any of this work for you? https://www.monoprice.com/mobile/cat...0optic%20cable

 

Thanks Stuart. yes making a loop would be inexpensive but they come in different sizes and I don't know the specs.

 

Couldn't you use one of the existing fiber cables as a test? There are some on eBay and Amazon too.

 

are there unused ones sitting in my trunk?
I'll check ebay again. I wasn't successful before

 

The fiber optic link is the MOST data link. Since the car is configured for navigation, my guess is some type of fault will be generated if the nav. unit is disconnected from the MOST.

 

Try Amazon too, there are many MOST cable there. Actually now that I think about it, I am not certain this would work unless you could cheat the system into thinking the GVIF is the NAV as I believe it is going to be looking for the module you would be disconnecting, I doubt it is a passive system as the NAV also feature a touch interface.

 

Thanks Stave, I assumed that initially but as I read it in the training manual, as long as the loop isn't broken, there are no errors generated.

Now what that does to the function on the touch screen is the question but since MOST loop is closed and GVIF is the only connection to the touchscreen, I'm curious to see what will happen if anything.

The loops are cheap if I find the right size:-)

 

I suspect your right and that's really what I'm testing because currently if we touch the nav screen, we get a connection to the box via the "agree" message. In theory it shouldn't be passive. The TSD has it's own code and I have no idea how to access it, but between the two something will either error, as Steve suggests, or nothing happens, or the connection goes through.

It's worth $20 for me to find out.

Yes I have way too much time on my hands and have become disheartened in looking at the HUD options.

Looks like this Male loop would work:

 

By all means go for it, it's fun and perhaps find a way around OE design. Now if SDD could be integrated into the TSD... As far as the code for the TSD, I would still like to find a way to customize the graphics, I've seen it done before, most recently with the David Brown Speedback X150 conversion.

 

Well I finally gave this a shot. I didn't work.

My hope was that the GVIF input into the head unit was passive and would accept a signal, but as jahummer alluded, the system looks for the Nav unit itself.

Steve, FYI, no error codes thrown with the loop in place before turning on the ignition. The Nav button on the touchscreen just goes gray.

I did then plug in the power to the nav unit and the GVIF connector only while leaving the Most ring out of the loop, hoping it would trick the TSD into accepting a signal but as Steve indicated, it must be coming from the MOST ring, so I surrender to my $19.00 experiment.

Stuart, FYI, the Audi/ BMW/ Volvo test rings are all the same size and fit our Jaguars, so thanks for the advice. I'll keep them for future diagnostic needs.

It's a shame SDD doesn't allow you to manually reconfigure the TSD. Then we'd have some fun. I guess the final test would be to remove Nav from vehicle configuration, but I don't see how that would allow the TSD to still accept a signal. I'd love to know the code in the TSD.

Oh well KJ, we're still touching buttons

 

So it seems. You gave it a good shot, thanks for trying!

 

I took a shot at analyzing the electronics inside of the touch screen unit to see what can be done to force the touch screen to show what is coming in the GVIF input (which connects to the trunk NAV unit) when the car is in reverse.

The display is a Toshiba LTA035A350F touch screen display. It receives video in the form of a parallel-delivered 8 bit R value, 8 bit G value, and 8 bit B value, which comes to the display via a wide ribbon cable from the circuit board closest to the display (which I will refer to as the 'bottom' board).

Inside the touch screen unit, on the bottom board, the GVIF video feed coming from the NAV unit is delivered to a Sony CXB1458R decoder chip which decodes it into parallel 8 bit R, G and B values, which are output onto a bus that leads to the Toshiba display.

Meanwhile, on the top board, data from the MOST network is converted to a video display, which I believe is also in the form of 8 bit R, G and B values, which are delivered via a ribbon cable from the top board to the bottom board, where those signals couple through TI Z245 family tri-state buffers onto the bus that leads to the Toshiba display.

The touch screen unit's internal controller enables either the output of the Sony chip or the output of the tri-state buffers, so that either the video created inside of the touch screen, or the video from the NAV unit (but not both) drives the display, based upon whether the user has selected the Navigation screen or not.

I believe the control signal that makes the video selection is also on the ribbon cable between the top and bottom boards. My next move is to verify this theory.

If the control signal is on the ribbon cable, then the system could be hacked relatively easily by interrupting that control signal at the ribbon cable, and inserting a very small logic circuit that forces the Sony chip on and tri-state buffers off in response to an incoming control signal, e.g., a signal indicating the car is in reverse. If the enable signal is on the ribbon cable, it is a transistor or two added to the circuit to accomplish this, which I believe can be done within the existing touch screen housing.

I believe what everyone would want would be to have a control line that forces the video from the NAV input to the screen, or alternatively allows the touch screen to behave normally. In the forced mode, the video would be whatever is produced by the electronics in the trunk, e.g., the NAV output, backup camera video, video gauges, DVD video, etc., as has been implemented by others in this forum.

If anyone would need a different function than simply being able to force the NAV input to the screen in response to a signal control voltage, let me know, as I would like to be sure I can cover everyone's need before I develop a solution.

Note that if I work out a solution, to market it I would have to have a core swap, or a core charge, for the touch screen assembly so that I can have enough touch screens on hand to keep inventory on modified units.

 

twhumphrey thank you for taking this on. Look forward to your results.

I am still very interested in knowing how to hack the TSD graphics. I know it can be done because I have seen it before.

 

Yes indeed, looking forward to your results.
While you could leave it up to the user to provide a 'front end' to the control voltage, it might be useful to build in the ability to take a control voltage from multiple sources, say 2 or 4, such that multiple truggers could be used, other than the backup lights (such as a manual switch to turn on a front parking camera).
Best of luck!

 

twhumphry, there are also the Fakra connectors on the head unit. WhiteXKR was looking into those but abandoned them.

Cambo is also convinced that they could be used for back up camera as he has used them the add back up cameras on Land Rovers. I was working on this with him. He ultimately got side tracked with higher priorities and deferred pursuing it to a future date TBD. I'm not sure his availability but he is a resource.

See this thread
https://www.jaguarforums.com/forum/x...camera-171736/

I think any resolution that would be most useful is one that allows members to resolve without "opening the TSD" as not all of us are tech savvy, but definitely appreciate anyone taking it on.

 

I have some hope that my hardware workaround may allow me to enable the Fakra connectors to receive NTSC or PAL video. Once I start hacking on this I will find out.... and let everyone know.

 

I'm still waiting on a car to arrive that I can test on myself, rather than doing stuff long distance. Not long now... although that's what I said last time...