when my deck was installed, the guy ran a power wire from the fuse box "25 amp fuse" to the aftermarket deck harness.

Why wouldn't he just use the power from the adapter?

Any reason for this?? Or is it just for extra protection.

 

if the deck is high power, the factory harness won't supply enough current.
Best to run a wire from the fuse box.
I took a tap off the power wire for my amps, so it comes stright from the battery

 

That's a smart idea.

 

That and factory wiring sucks

The only factory wires that I'm using are the Ignition wire (ACC) and the illumination wire. Everything else is my own wire - from power wires to the speaker wires in the door.

 

Is it on the ignition (red) or constant (yellow) wire?

What year and make of car?

 

It's a 2000 Cavalier. The power wire is ran from a fuse to the aftermarket wire harness.

 

There should be 2 wires from the fusebox or ignition harness for that car.

 

^ Constant should be in the harness. Ignition is not though.

 

Harness' for those cars are $150 because of the alarm etc. I actually have one sitting here I don't need.

 

The constant in the harness is too small for todays decks.