Hey Red....et al;
I installed the very same Dakota Digital Quad Gauge several years ago.
Very nice!!!..considerable work!!!!...worth it for me.
Here goes:
Voltmeter interface: Easy and straight forward. One dedicated wire and system ground, of course.
Water temperature: I fabricated a custom water temp sensor (supplied with Quad Gauge) journal on the output side of the thermostat en-route to radiator hot/pressure port (on top).
I left the OEM water temp. sensor to ECM circuit intact and un-mucked with fearful of additional electrical loading by the Quad Gauge.
Oil Pressure: The OEM pressure switch, gated 6psi, is an integral part of the oil journal in cylinder head. Remove it and you will see what I mean.
I turned a custom adapter on a lathe that replicated the geometry of the OEM switch...then a "Tee" to service an off-the shelf oil pressure switch for OEM circuit and the oil pressure sensor supplied with the Quad Gauge.
Fuel Level: I worked with the engineers @ Dakota Digital to modify this part of the circuitry of the Quad Gauge. Instead of measureing the sourced or sinking current of industry standard fuel level sensor (typically 240 ohms) the Quad Gauge fuel level input stage was changed to a buffer amplifier then A/D conversion to microprocessor based on 0 to 5Volts.
What you will need to do is go into the programming function of the Quad Gauge and select "custom fuel" sensor. Then simulate the OEM fuel level sensor voltage at 33%, 66% and 99% fuel remaining. The microprocessor interpolates everything in between.
One word of caution here!!!!!....fuel remaining in % is ONLY as good as the OEM fuel level sensor....which SUCKS as a linear analog signal device for measuring fuel level.
I made drawings and schematics for the engineers @ Dakota Digital detailing the modification. Let me know if they no longer have them on-file and I will send along to you. Dakota Digital said they were going to assign a new part number for the change. They never told me what it was going to be. Just tell them you want to install it on Triumph Rocket and perhaps they will remember. They were great to work with....VERY Accommodating.
There is also an external alarm signal path to light an LED should any or the parameters be outside the user programmed limits, high and low for volts and oil, high for water temp., low for fuel remaining. I hooked this up to an external LED....pretty nice.
It's a lot of work to integrate the Quad Gauge on a Rocket but I considered it a fun and a worthwhile challenge.
I REALLY Hope this Helps.....
Got questions??????....I am just a pm away!!!!!
Good Luck
Gary