Thanks for the kind responses everyone... Lots of good information. To give a little more background, I am designing a dashboard instrument cluster, and this is a small subset of that. I'm trying to plug into an existing car switch pack which contains some switches, pots and some LEDs for position indication, and what I'm trying to do is read the position of the switches and then light the correct LED.
The switchpack looks like this:
and is wired like this:
I am then plugging the pack into my board using a ribbon cable. The board I'm plugging it into is wired as below. There's a lot on there but most is not relevant. The incoming connector is labeled CON_LIGHTS and is in the bottom right along with the transistor array.
So each of the 8 channels on the transistor array is powering 1 led on a 470ohm resistor, so I'm hoping to send 12v to the led via the array. The switchpack then has a ground rail which connects all leds to ground so I must supply + power.
It sounds then that I've got the array the wrong way around... Would there be a better tool for the job?