Are there are any updates?

[torhne]

I am having a tough time visualizing the diagrams for the D2 connector and its transistors. I have a diagram but wanted to see up close one that was already done, if you have it yet?

[sparcules]

@torhne, Sorry, I didn't document this project very well. I have two Arduino projects listed here. XJ_Cab_Display and XJ_DR44_Alternator. The XJ_Cab_Display uses a Teensy 3.2, provides in-cab control and display, it drives an OLED screen, has a two push button interface, and is mounted in the dash of my XJ. And the XJ_DR44_Alternator uses an Arduino Nano, controls the voltage output of the DR44 alternator, uses a serial port to have COMMs with XJ_Cab_Display, has not user interface, and is in a PVC tube under the hood.

D2 for my in-cab control and display is assigned to the Mode push button that is mounted in the panel. I use pull-ups in the Teensy and the button shorts D2 to GND when pressed.

D2 for the alternator driver, I found a wire under the hood that is only hot when the engine is running. This works well in my 1989 XJ. Models after 1990 may vary. It's been a while since I hooked this up and unfortunately, I didn't document it very well. If this is what you're looking for, let me know and I can trace the wire and let you know where it's located.