i know this post has been posted before, but i am still missing an easy way of doing it. i am trying to find a hot wire that is on when the ignition is on that is under the hood. i am trying to put some LED running lights in that are always on when the truck is on, but i need a 12v supply that is powered under the hood. i would run power from the fuse box inside the cab, but then i have to run a wire from inside the cab to outside the cab.

 

I just wired my Troyer E Fans, and they had me tap into the red with a yellow stripe wire in the plug that sits right in front of the middle plug of the three main plugs by the firewall on the passenger side. It was one of the outside wires in a piece of split loom about 4" long. It is on with ignition but off all other time. Im sure you could tap into that to trigger a relay for your lights.

 

These three plugs are the harness connections to the PCM (powertrain control module). Be careful when splicing into these!!!

 

thanks for the reply, i havnt seen that one yet. i think ill keep looking though, as bucko said, i dont really want to tap into anything going directly into my PCM. i have seen that a lot of people are just using open fuse box locations, but i am not quite sure what i want to do yet.

 

According to my 2005 Ford factory schematic wiring book, there's a red wire ("hot only with ignition in "run" or "start") with it's own connector that pigtails off of one of the 3 large connectors that connect to the PCM.

Look by one of the three large connectors that goes to the PCM; look for a single connector that comes off of one of these three large connectors with a large guage red wire. This connector supplies ignition switched power to the "central junction box" (fancy Ford name for the Fuse box!). You can tap into this under the hood.

Be sure to place an INLINE FUSE when you splice into this, as you are using an unfused connection when you tap into this wire at this point.

 

Like I said it is in a seperate harness that is in front of the middle plug on the three harnesses. Its not in one of the three main ones. I dont think Troyer would have you messing with it if they thought you could mess something up. Just make sure you disconect the battery ground before you do anything and I would solder and heat shrink the connection thats what Troyer had me do.

 

The wire Im talking about is not that thick thats why I said it could be used to trigger a relay. Doesnt have to be fused then.