I'm about to begin the install on a Mychron3 XG Log and I want to make sure it's done correctly. Since there are a number of people with these systems here, I thought I'd check my understanding against the more experienced users. Where possible I'd like to use existing signals/sensors.
This will be going on a 1995 slowly winding its way towards ITA and it will replace the dash entirely. For the next track day (my first focus) I'm trying to get speed, RPM, water temperature and oil pressure (dummy light at least).
-RPM pickup wire (blue) connects to the dash board/datalink tach connection.
-Speed sensor provides +V, GND from the XG Log and a sensor line that varies between +V and GND depending on the hall effect (didn't get these, so I'll need to prep a new set)
-Water temp - Here things get a little hairy. The 1995 wiring diagram makes it look like the dash has a signal line (Blk/Blue) that would connect to the analog input. The ground line would run to the dash ground. That leaves +Vbattery and +Vref coming out of the XG Log. If I'm not powering the sensor off of the XG log, do either of these get used? Tie the Vref to the dash +12v line? Both of them?
-Same as water temp applies for the pressure switch, although I'm less concerned about wiring that up.
Am I even close? Also, does anyone have any idea why the horn ties into the datalink?