Sylvain:
First... it's assumed that you're referring to the Red wire on Pin 1 of the 37-pin connector on the SV-EMS-220/221. (There is also a 37-pin connector on the SkyView display, also with a Red wire on Pin 1.)
Short answer - wherever you want
Longer answer - This is the wire for the "Voltmeter 1" function. It is optional, especially with a VPX which will also report system voltage. If you choose to use Voltmeter 1, connect it to whatever point of your electrical system you want to monitor the voltage. Common connection points are the battery + terminal, the alternator + terminal, or your main voltage distribution bus. It will then display the voltage at THAT point of your electrical system.
One of the Black (ground) wires of the 37-pin connector (Pins 3, 5, 13, 16, 17, and 30) of the SV-EMS-220/221 should be connected to the main GROUND bus of your electrical system, ideally the connection point as the engine block's ground for best performance of the engine sensors that use the engine block as a ground connection, such as the temperature sensors. In the SV-EMS-220, Pins 3, 5, 13, 16, 17, and 30 are bonded together, so which one you use is up to you; some of the black wires are bundled with other wires.
Hello Dynon,
I would like to know where I have to connect the DB37 pin 1 (red wire) with a VPX installation.
On a second hand, can you telle me if I have to connect on of the DB37 black wire (Ground) to the ground plane ?
in advance thank you
Sylvain