need help finding "hot" wire under bed

im trying to find a Hot wire under the bed but i really want one that is only hot when the key is in the on position. i see people talk about tapping off the trailer harness the problem is i have a 4 pin harness so idk if my harness has a acc hot wire. please point me in the right direction.

 

I don't think there is one.

I gave up looking and just ran a new wire from the engine compartment fuse box for my compressor and camper shell lights.

 

could use the running light wire, and then just hit the parking lights on when you need juice. or there is always the fuel pump wire, but better seal it off pretty good if you tap into it.

 

I don't know about under the bed but there is one on the brake lights but you have to have the lights turned on. That is how we hooked up the bed lights on my dad's taco. Works good, look below.

 

Can we ask what you are trying to power?

I do not like to tap into existing circuits for power unless the circuit can handle the load. Many automotive circuits are not "over-engineered" enough to allow much additional draw, depending on where you are tapping in.

The great way to do it is using a relay that is powered on by a key on circuit. The control side of the relay uses very little power (amps) and can then send power to an accessory at the feed side rating. Put a fuse or fuse link in from a battery lug and run the wire back to where you need it. Calculating the amount of wire and size is easy once you know what you want to run. Just use a calculator like the one here http://www.powerstream.com/Wire_Size.htm to see how much the voltage drop would be. Use a large enough wire to handle the load and keep the drop to a minimum.

HTH