JL audio amp problems, "protect" light

SOURCE: Car amp's stopped working. Putting out a heart beat sound through subs but no bass.

could be low current ,disconnect all power including ground for 20min N.B most amps will seem to be shorted at output but this is normal due to damping ratio.

SOURCE: Jl audio e6450 cuts out above mid-volume

take a look at the power, ground and remote wires. the power and ground should be a minimum 6awg in wire size, and the remote wire at least 12awg. it sounds like your drawing a lot of power,so smaller wires usually mean more heat...the amp will turn off into protectedmode if it gets hot or is used for along period of time,so on any road trip make sure if isnt msothered by sleeping bags,coolers etc...just like any major electronic component, it needs room to col off.

SOURCE: jl audio 500-5

Assuming that you've confirmed that the speaker is in good working order and that the wiring isn't shorted in any way...

There are separate power supplies for the high and low amplifiers. It's possible that the one for the sub output has failed. If that's the case, the output transistors probably failed and that's what damaged the supply.

Generally, I'm willing to help people repair their amps but this is a large, complex amplifier and it should be repaired by a qualified technician.

SOURCE: i bought a 500/1 jl audio amp and also a w7 10 sub

if its cutting off and right back on then check your ground and your power wire makes sure both are connected good and none of your fuse's are blown, either that or you got a wire hooked up backwards in the sub.. but my guess is that the sub is hooked up wrong... that sub should be hooked up in a series or in parallel,

ok if your running just one speaker, it should be hooked up like this and 2 speakers are a different way...

this is parallel :pos to pos , neg to neg, then one wire coming from pos on sub to pos on amp then neg on sub to neg on amp but bridge the amp on your amp should be 2 pos and 2 neg in two different channels take the pos off the sub into the pos on 1 channel and then the neg from sub to the neg on the other channel,

this is series : on the sub it will go pos to neg then the other neg and pos will go to the amp, but make sure the pos and neg r on different sides of the sub, dont hook them both to the same coil

if your need more help give me your email and ill send you a pic of how to do it...

SOURCE: jl audio 250/1 thermal light

i was having issues with this amp as well, the thermal light was flashing every couple seconds. i checked all the connections and i discovered that when i pulled the power wire out the thermal light was still flashing, which tells me that there was no power from the power wire, but it was getting power from the remote wire. i know this because it would stop flashing when i removed the remote wire. but wouldnt start when i didnt connect the remote wire but connected the power wire. so with the power meter i checked the fuse and it was a little loose so i screwed it back in and the amp turned right on. 
to make a long story short, a flashing thermal light is a power supply issue.