I installed a subs into my cousins car a in January, no problems during the install.

About 2 months ago he told me he had a protection light, so I went over and checked everything out and it looked all good. So he called up crutchfield and he got a new amp, I assumed the amp was bad.

New amp, installed it, and same thing. So I checked the fuse at the battery and that was blown, so we got a new fuse, and fuse holder. It worked, the subs were playing.

2 weeks ago I get a call from him again about the subs not working, so I check it out, the fuses are all good. Now I am not sure at all why the amp stays in protection mode. We check all the wires, everywhere. And the amp i still in protection mode.

Not sure what to do?

You guys are going to laugh but this are his specs

MTX Thunder 10's - 2 of them
Visonik 400 WRMS amp
Some Sony HU

The ground is good and so is the power.

 

Get a meter and start testing wires.

 

I did that.
I tested the Power wire, and the output coming out from the amp to go to the subs.
The power wire checks, there is no output coming out of the amp.
I am not 100% sure how to test the RCA cables

 

check the ohmload of the woofers, make sure the final impediance is the correct impediance. Seems like one of the woofers is cooked, and the other is giving off a impediance the amp can't handle. Also Unplug the speaker wire(s) from the amp and then turn it on see if it still goes into protection...

 

Oooooo Good idea...

I remember checking to see if the sub could move in and out and they were, would they still move if they were cooked? and when I checked them they made a faint noise every few mins....
but yea ill check that when he comes back from vaca

 

test the resistance of the sub. simple way to see if the coil is bad or not.

 

unplug the RCAs while the amp is on, and see if it goes out of protection. Definately check your subs/speakers with a DMM to see if a speaker is shorted out somewhere...

did he change anything recently?

 

No, not that I know of.

One more thing how do you check to see if the subs are blown, I have a MM I just don't know where to connect it...