I have a Clarion amp, when I turn on the stereo the amp won't come on? I check all the voltages on the wires(fine), powered up the amp in the house and worked (fine), noticed that when i took the power wire off and took a voltage reading it was 12.8 and rising, when I put the power wire back on the amp it went down to 7.6?, I have a .5 farad cap and thought it might be that but did the same thing when I bypassed it. The wierd thing is that it worked fine 2 weeks ago and it worked in the house on a power supply (with the same current levels), any suggestions?
If you're voltage is dropping that dramatically something ain't right. Try measuring the voltage at the battery with the amp hooked up. If its 12 volts there and 7.6 at the amp(you're not measuring the voltage of your turn-on wire are you?) you've got to have a bad power wire connection somewhere, something to account for that much off a voltage drop.
If for some strange reason you ARE measuring the voltage of your turn-on wire then the voltage drop is a lil more understandable. If this is the case disconnect the remote wire from the amp and try jumping 12 volts from your power wire to the remote input. If that gets it to power up then you may be able to solve you problem using a relay: