Let me start out by saying there might be a security code needed to make the radio work after power is removed. I don't know if that applies, but if it does, be sure to know the code before disconnecting it or pulling fuses.
The easiest way to find the culprit is to disconnect the radio, then see if the amp turns off. If it turns off, and turns right back on when the radio is reconnected, the radio would be suspect. If the amp stays on, a relay could be sticking on. An alternative to pulling the radio is to remove the two fuses. One is for the switched power that turns the radio on with the ignition switch. The fuse for the memory circuit is usually tied in with some other circuit that is always on. Interior lights is the most commonly used circuit, but the horn or brake light circuit could also be used.
Most radios will not switch the amp on and off directly because that's a lot of current for the switch to carry. Instead, the radio typically turns on a relay. The problem is, that relay could be in the dash, in a fuse / relay box, in the amplifier itself, or an electronic circuit in the amp. I'm sorry I don't know where that relay lives, but if you can find it, it will provide clues if it clicks off when you pull it out of the socket.
Thursday, April 8th, 2010 AT 6:25 PM