Protect light is on

Posted by pbabin on Nov 13, 2009

If the amp is in protect mode, it probably has shorted output transistors. To eliminate other possible problems, do the following. I'll assume that you've checked the amplifier's on-board fuses. Disconnect all speaker wires from the 'amplifier's speaker terminals' and disconnect RCA/signal cables from the amp. If it powers up normally, the speakers/wiring need to be checked. If it still shuts down (goes into protect mode), the amp almost certainly has shorted output transistors and will need to be repaired. If the amp only shuts down when it's driven to relatively high volume, you need to confirm that you have sufficient power supply voltage. With your multimeter set to DC volts, the black meter probe on the ground terminal of the amp (not on the point where the ground wire connected to the vehicle) and the head unit on (so the amp will have remote voltage applied), touch the red probe alternately to the B+ and remote terminals of the amp. If the voltage is below ~11 volts, you need to check the wiring feeding whichever line is too low. If both the B+ and remote turn-on lines are low and your battery is fully charged, you may have a bad ground connection.