Will splicing power for my gauges from the cigarette power outlet take any power away from that? I dont know much about electronics. I still want to be able to charge my cell phone or plug in my laptop with its GPS. I figured out that the red wire with black spots is the 12volt switched wire, the brown is the ground and the red/grey wire is a dimmed light source.

 

I don't have the wiring diagram to tell you which lead is which, but from an electricity standpoint, branching a power circuit shouldn't "starve" the cigarette lighter of power. Both circuits would still see 12 volts. The problem you may have is that if the wire from the battery to the splice is not a big enough gage (i.e.: thickness) for both loads (you didn't mention why you need the splice) then you could risk overheating that wire. Each load will draw whatever current it needs to draw when it's turned on (the current would be the device's rated watts divided by 12 volts). I don't think that the battery charger draws more than a fraction of the current that the cigarette lighter does, but if you're splicing in some high current, full time load then this could be a consideration. You probably won't have a problem, but I'd have somebody check the ratings of your devices before proceeding.

 

Another thought... even if your new load doesn't have an impact on the wiring, you may need to resize the fuse feeding the cigarette lighter. I don't have the fuse size in front of me, and it's still probably not an issue, but these are the things to consider before playing with electrical circuit.

 

I want to install Cyberdyne digital oil temp/pressure gauges. Im not sure on their wattage, but it needs 12volt switched, a dimmer, and a ground.

 

Check on the dash lighting circuit (do a search) as you can find 12v dimmable for the lights. A small load like the gauges shouldn't hurt power availability. Carful witht e tap, though, and tape it well. I usually throw a small ziptie over the tape - don't want it coming undone a year or two from now - or ever.