After I finally got my Alpine HU installed, I attempted to use my amp. I've got the signal going through Monster Cable RCA's, power and ground through 4 gauge, and the turn-on lead coming out of the back of the HU. Everything is connected up, but whenever I turn on the HU, the amp will not turn on. I'm using a MTX 421D, which was working great whenever I took it out of my Camry a month ago. Basically, I've checked the fuses and the turn-on lead, and everything's good. Any ideas as to what the problem could be? If it helps any, I used to have the Bose HU, and am using the Crutchfield Interface Adaptor.

 

Well, no turn on is still a power issue. Do you have a test light?

I would run over the fuses again, and make sure there isn't a 2nd fuse (like by the battery in-line with the power lead) that isn't mixing into the confusion. And then probe with a test light at the amp. Making sure you have good power and ground. Then check the fuses on the amp itself. if you have all the ingreedients, it should power up. If not.......blown amp?

 

There's only 1 fuse between the battery's positive terminal and the amp's positive terminal (40A). I've taken a multimeter to the positive terminal and ground, and it's getting voltage. I've done the same with the turn-on lead, but still no go on the amp. The thing I find weird about it, is that when I connect the positive probe to the in-line fuse in the power wire near the battery and the negative probe to ground, I get 12V. But if I use the positive terminal of the amp, I get about 6V. The same thing happens with the turn-on lead terminal of the amp (when the HU is on)... I get about 6V between the terminal and ground. I don't know if this is normal or not, but it seems very odd. I hope my amp's not dead... I really don't want to have to buy another one.