I'm getting ready to wire up my carputer screen and the two RPM switches for my aux. port and VDI activation and would like to get some input on which method might be best.

I was originally going to take a 15a relay switched off of an acc. source for both items (since they draw very little) but I'm thinking to myself that it's way overkill for a 7" LCD and some switches.

So my other option is just pull directly off of an accessory circuit of my choosing and see how it goes. I'm thinking this method will be ok as long as I choose something that's not vital to the vehicle's operation, but I don't want to go off the head unit's harness so I'm looking for suggestions on where to tap in.

Thanks!

 

cigarette lighter

 

You should do your original idea and use a relay connected directly to the battery, triggered by ignition on. No matter how many amps you think you will be pulling, it is alot safer to do it this way.

Run a fused power line from your battery into the cabin and so that you do as little cutting of your original harness, pick up a 'add a fuse' fuse holder from your local parts store and trigger the relay off of that. Just plug it into your cabin fuse box and thats it.