Today im installing an aftermarket pioneer radio and i bought the harness to do so and set up the wires. Heres the problem , the only way i can get power is to attach the yellow and red wire from the radio to the battery constant from the truck which i know is the reason that it stays on after the truck is off. But with the truck on and a test light there is no other wire that draws power, only the battery constant. So can someone lend a word of advice? Am i missing something? I currently have it hotwired and am just taking the faceplate off hoping that won't drain the battery but i don't have high hopes for that and would much rather it be properly installed. It is to be noted also that the stock radio works fine and i've checked both accessory fuses in the truck (4wd and the special option accessory fuse)

 

You should have the 'memory' wire attached to the line that is "HOT" all the time (so your radio doesn't lose the radio presets or the time displayed on the clock); but the 'power' line needs to be connected to a line that is only hot when the ignition key is turned on.

 

I believe the yellow wire is supposed to be hooked up to the power constant. The red wire is supposed to be hooked up to the line with power only with key on. If the old radio worked properly then the correct wires are there. You just need to tap into them. You can check with a meter.