There is such a vast array of vehicles and ignition systems
that it is impossible to provide much information here. With some
diligence you should be able to find information specific to your application in
a service manual, best source, or on the Internet.
I recommend that you find a good clean switched +12v power source as close to the actual battery as possible. Connecting to, or near, the charging system is not recommended. I actually prefer to run my power supply directly from the battery with an in-line switch. A very good ground is essential to a successful installation and I would take the extra time to be especially sure that you have a very good one.
I don't think Actron™ is involved in the tachometer business any longer so I am making an older tachometer Installation page available here for a general "overview" of basic connections.
This is the very best information tech site I have found and it covers a lot of applications. Where do I connect the green wire is about the best one.
Raptor Performance™ has an excellent installation page as well with notes for a lot of vehicles and you may find what you need there.
This Unit has 6 pads
on the PCB for external connections:
 | +12v Red |
| Ground Black |
| SPI Out White |
| Tach
In Green |
| Shift Light Red (+5v from the PCB) |
| Shift Light Black (Ground) |
NOTE: The Shift Light has provisions on the board for an LED if you are mounting one in your project box. I have also used pads to take two wires out of the box for a remote light. This is a 5 volt circuit from the PCB regulator with a series 620W resistor (R1). You can clip R1 and use your own remote circuit with Q3 (VN10KM) sourcing ground. Current regulation is strongly advised!
