Kenwood car amplifiers have built-in protection modes that shut down the amplifier when conditions that may damage the amplifier occur. When the amplifier is in protection mode, the amp ceases operation. There is no reset switch or other way to turn the amplifier back on. Rather, the user must take the time to eliminate the possible causes of the problem that causes the protection mode to turn on.
Turn off the car's electrical power, and then remove the negative battery cable from the battery while you troubleshoot the amplifier.
Check that the speaker wires are not short circuited. If bare speaker wires touch each other, it causes a short circuit in the amplifier's output circuit, triggering the protection mode. Check for loose wires or stray wire strands that may be short circuiting the output.
Check that a speaker wire is not accidentally grounding. A bare spot in the wiring, if it contacts a metal surface, will cause the amplifier to go into protection mode. Check the speaker wires for bare spots or cuts that may be contacting a ground.
Check the amp's temperature and ventilation. If the amplifier overheats, the protection circuit is enabled. If the amp is hot to the touch during operation, this may be the problem. Consider moving the amplifier if it doesn't have several inches of open space around it in all dimensions to provide a flow of cool air.
When you've addressed all of these issues, reconnect the battery's negative cable, and turn on your audio system. If the amplifier goes back into protection mode in the same manner as before, contact your dealer or Kenwood for information on servicing the amplifier (1-800-KENWOOD).