yesterday i installed an alpine cda 7842 cdplayer im my 1997 cavi. it comes on and keeps memory, but there is no sound. when i hook my old cd player back up, there is sound. the alpine unit was just removed from my friends truck the other day and was working fine. when we hooked it up and no sound was coming we started looking for the problem, then the sound kicked in. when i shut the car off and started it back on, the sound wasn't working. what the @!#$ is wrong with this.

If there's a short in the speaker wires somewhere, it could turn off the deck to prevent something from frying. Wire up one speaker at a time. Or if you have a shorted voice coil in one of the speakers, it'll do the same thing.