Righto, here's my quick explanation of how to wire in a 2 wire shift light (ie any 12v light to act as a shift light)
It can be done in any order really so it's up to you where to start.
However I recommend that you disconnect the battery before you do anything else!!!
I started by mounting my light on the steering column cover. The front of the steering column pops up, then there is two clips each side at the back which you need to release. Then the whole top of the steering column cover will come off. Then mount your light however you would like to. I used 2 self tapping screws into the plastic. Remember when you drill and screw into plastic, take it slow so it doesn't crack.
Since the light came with some wires already attached, I bought a simple plug to attach the wires to which can be easily disconnected if you need to. You do not have to do this and it can be simply crimped or soldered together, your choice.
I then got a 12V positive supply from the fuse panel in the drivers footwell. There is a few spots you can use, I just used one of the spare relay slots with a blade crimp going into it.
Next you need to run the other wire to the pcm. To do this, run it under the dash to the passenger side footwell. Remove the plastic cover from the footwell (If there) not forgetting to remove the footwell light from the cover as you pull it out (also if light fitted). Look up and you will see the through firewall gland. From the engine bay it looks like this...
Run your cable through there, ensuring you have enough to get to the pcm, which is located underneath the coolant reservoir tank.
Remove the plastic cover by unclipping the front end and slightly sliding the cover towards the rear of the car to unclip the back end.
Using a socket, (size I can't remember!!) undo the connector farthest away from the engine. (Red connector)
The pin I received was off an old pcm so it already had a wire on it...
Carefully remove the grey plastic cover from the top of the connector and push the pin into slot 47 until you feel it click and lock in.
In this picture it is the brown wire I am holding in my hand. Every slot is numbered except the ones where numbering is not possible.
Again connect the wire from the pin and the wire from the shift light as you see fit. This time I soldered the wires together and for safety measure put an insulated tube crimp on it.
Put everything back together and neaten up the job.
The only thing which needs to be done now is for your pcm to be set to have shift light enabled.
And that is the install of a shift light. The Pin 47 switches to ground (car chassis) and the bladecrimp is supplying 12v from one of the spare relay supplies. My 12v globe has a red lens over the top of it including a red cover for the tube itself.