Hooking Up An Amp With No Remote Turn On
 

I have a factory amp inside the car somewhere, its 2004 300M, and i had to hook up the remote lead to the harness to get my head unit to play through the speakers. So now what do i do to get a seperate amplifier to turn on if i wanna hook up subs? Or will it just turn on from the deck automatically?

Just hook it up to same feed.

If you are worried about the remote lead not supplying enough juice, you could always wire in a relay. The relay has a 25 or 30A handling. I usually use them for more than 2 or three amps. This way you dont have to worry about frying the remote out on your deck. The relay has a 12 volt + constant, a ground, an input (remote off the deck) and an output, which you can splice to multiple amps.

Ok and where would i go to get a relay? and how exactly does it hook up if the remote turn on is already in use from the harness to the back of the deck? Or is this something that i'd hook up seperate?

Its not that i'm worried about the remote lead not supplying enough juice...its the fact that i can't use the remote turn on from the head unit...its hooked directly to my deck from the harness so that i can get sound outta my deck.

Cut the wire and add some more going to the back?

You would have to disconnect the lead coming out of your deck to wire into the relay. Then the output from the relay would look up to both amps. You can get a relay at any auto parts store. Should come with a harness as well.

Taken from http://www.the12volt.com/relays/relays.asp

Why do I want to use a relay and do I really need to? Anytime you want to switch a device which draws more current than is provided by an output of a switch or component you'll need to use a relay. The coil of an SPDT relay that we most commonly use draws very little current (less than 200 milliamps) and the amount of current that you can pass through a relay's common, normally closed, and normally open contacts will handle up to 30 or 40 amps. This allows you to switch devices such as headlights, parking lights, horns, etc., with low amperage outputs such as those found on keyless entry and alarm systems, and other components. In some cases you may need to switch multiple things at the same time using one output. A single output connected to multiple relays will allow you to open continuity and/or close continuity simultaneously on multiple wires.

Special Applications with SPDT Relays

Second entry down describes with a picture how to hook it up.

ok great..thanks a lot for your help man..appreciate it