Thanks for the suggestion.
Bob
Hello Sean,
Just a few more quick thoughts:
For a while I liked my idea of Velcro-ing an iPhone over the Trip Computer and enjoying all kinds of functionality via Bluetooth to the aftermarket stereo. A kludge for sure, but it worked.
Then after reading your fascinating posts about redesigning the Trip Computer, I wanted to try something similar, but maybe somehow hack into a Garmin GPS and cobble together a Raspberry Pi based interface to provide extra functions?
Or dig into the Garmin’s Linux OS and application software to customize it for the XJS? (Hardware interface might get really challenging - not to mention understanding how to retain GPS functionality and add features without source code!!!)
But now that you have enlightened me about how to operate the existing Trip Computer, I am enjoying its basic functionality! I must be showing my age - I guess that I must be very 1980’s…
In any event, for now I have an old Garmin Nuvi glued to the passenger-side ashtray cover - the antenna is nicely exposed to the sky through the windscreen. And for the moment, I’m enjoying the Jaguar Trip Computer as originally designed.
Maybe down the road I will try to understand how to build up a separate interface for a dedicated processor to monitor various sensor inputs, and keep nice statistics about the health of the car. Wish they had required OBD II a bit earlier than they did! (a nifty iPhone bluetooth interface to OBD II is available). I wonder if anyone has deciphered the proprietary Jaguar diagnostics signals, and created DIY hardware/software to process them.
Endless fun!!!
Cheers,
-john
Ron,
I still have the one I pulled from my 94 parts car.
Please contact me offline for details._
Best to call me @650.455.1110
Steve
Hello,
Some thoughts have gelled a bit more…
Our beloved 1991 XJS Classic “Maxie” has an aftermarket stereo with Bluetooth. So we can enjoy a nice speakerphone, 45 million song music library, and Tesla-like voice command GPS navigation via the iPhone.
Recently dear Maxie had an episode with her Crankshaft Position Sensor. What if her iPhone could have diagnosed this and simply told us where she hurt???
Just a Dream at the moment: Build custom interface hardware and cabling to connect to her ECM diagnostic connectors, and possibly to her Trip Computer as well. This hardware isolates signals and routes them to a Raspberry Pi Linux computer (also hailing from her homeland!).
The Raspberry Pi, in turn, transmits coded signals via Bluetooth to her iPhone brain. On the iPhone, a custom app interprets and displays the data.
In the future, the app is expanded to utilize her voice recognition and synthesis. (We have already programmed “Siri” to respond to “Maxie”…) 
“The car is the closest thing we will ever create to something that is alive” - Sir William Lyons, Founder of Jaguar.