I have a Kicker IX-405D. It suddenly started acting up a few weeks ago. I haven't touched it or changed anything on the install for the past 3 months. Several times over the past 3 weeks or so, the amp would just spontaneously turn off (all channels in the amp go dead) while playing at only a moderate volume. I assumed this was the overheat protection kicking in, but it was probably about 50 degrees Fahrenheit outside, and when I pulled over, the amp was cool to
the touch. It did this turn off and turn back on
(probably took about 20 minutes to come back) about 4 times over a period of 2-3 weeks.

The other day it turned off and has no turned back on since. Today I took some time to examine it. The red light indicating that the protection circuit is on flickers constantly. I have tried disconnecting all of the speaker wires, as well as all of the RCA signal
wires, and no matter what, that red protection light keeps coming on. I checked the fuses and they look ok. I'm not sure what to do next.

Here is what the amp instruction manual says:

Red LED protection indicator is lit and there is no
output:
Case 1: Amp is very hot
• Thermal protection is engaged. Check for proper
impedance at speaker terminals. Also check location of
amplifier to ensure proper air flow around heatsink.
Case 2: Output resumes momentarily when system is
turned off and back on.
• Short circuit protection is engaged. With VOM check
for short between speaker positive and negative, and
between speaker terminals and ground.

 

from the sound of it, you might have a speaker grounding somewhere. That may cause the amp to cut out. Speaker wires would be a good place to start. I don't think it's the thermal protection if the amp does not get that hot

 

That's what I thought, but the protection still goes on when all of the speaker wires are disconnected so I don't see how it could be the speakers being grounded.

 

with a multimeter try testing the BAT and Remote power connections also make sure you have a good ground.

 

The ground should be fine, considering the amp gets power, it just kicks into protection override mode