I just installed a jensen dvd/cd player.
I got the diagram and just wired it straight to speaker wires, not the amp.
I was wondering if it is a need to have the amp in function.
There is no sound when i turn it on

 

There are a lot of posts about this, I have been reading them since I just bought a new head unit as well. The Mach 460 (your 99 has the Mach 460?), cannot be wired up by just replacing the head unit. The amps in the back control the 4 woofers..... just look around there are a bunch of very thorough explanations online including wiring diagrams and instructions on how to install your Jensen.

This is a good basic starting site for info http://www.flemworld.com/Mach460/Mach.html

 

I got it bro, Earlier I saw the blue wire wich was a remote start wire and I connected it to the other remote start on the head unit and bam it worked.
Ive installed many amps and I cant believe I didnt catch this.

Thanks guys.