Amp turns on, shuts off when car starts

[bmeger]

My amp recently stopped producing sound, randomly. I immediately checked all of my connections, seeing everything was okay. The amp's power light was on, so I assumed it was the subs. I hooked up a different amp to the subs and they worked perfectly, so that brings it down to the amp.

The amp is an MTX Thunder 300XD. When my car is off, the power light for the amp is on. As soon as I turn the car on, the amp shuts off. I checked the fuse on the amp and found that it was blown, so I replaced it. Still the same problem. I hooked up an RCA to aux cable from my phone directly to the amp, and the subs began playing fine, with the car off. As soon as I turn the car on, they stop playing and the amp shuts off. I should also mention I have an LC2i hooked up in the system as well.

I am at a loss here.

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[shizzzon 10+ year member]

Amp can't come on if the fuse is blown.

You need to state that every time the amp light goes out, either the fuse is blowing or you are at least checking it.

Because it has blown, i'm going to assume it does everytime.

You have something wired very dangerously.

When the car is off the amp comes on?

The amp shouldnt be able to come on unless it was in ACC mode.

So, with it being completely off, i'd unhook everything and inspect continuity among the three primary cables FIRST.

Next, swapping rcas plays..

Sounds like the amp is sourcing it's ground through the rcas perhaps?

Because you are using a LOC which are terrible, i'd inspect how you have that wired as it sounds the amp's primary ground may be running through it which is dangerous.

 

[bmeger]

Yes, I check the fuse every time the amp light goes out. The new fuse I put in has not blown.

The system worked fine for about 5-6 months, wired exactly as it is now, weird that it would randomly cause problems. What could have changed to make it do that?

Yes, the amp's power light comes on with the car completely off, as I believe it always has. Should it not?

What is wrong with a LOC? I'm a car audio rookie so any info I can get here helps out. Would you recommend getting rid of the thing and trying without it? The power and ground for the LOC are hooked up to my main power and ground cables and run into the inputs on the amp. There are wires running from one left speaker and one right speaker hooked into the LOC, and the RCA's run from the LOC into the amp. I had the system installed at a local car audio shop so I assume it was done correctly, I hope.

Thanks for your help, I appreciate it.

 

[bmeger]

Bump - still have not found a solution

 

[brian84corvette 10+ year member]

something is shorting out id bet

check all of your wiring to see signs of sparks / burns / black soot / anything that could short out anywehre.

 

[bmeger]

Okay new update

I've tried a number of things, and finally found something that worked. I fed a wire from my power input on my amp into the remote input, and the system ran perfectly. I replaced the remote wire and rewired it properly again, with no success. The only thing I can think of now is that the remote output on the lc2i is damaged.

Any other thoughts before I try anything else?

 

[massivespl]

Hook ur remote wire up to an IGN fuse and see if that works. That should turn amp on and off when u start the car and turn it off.

 

[What was that? 10+ year member]

The amp should not be on when the car is off. The remote wire is likely incorrect. If was jumped from a 12v source that could be a problem as remote signals are typically designed to be low power. I have mine fused with a .5 amp fuse and have never blown the fuse.(fuse not necessary, I'm over cautious). If it was jumped a voltage spike could have messed up the amp and forced protect mode. Check remote wire. It should have it's own wire coming directly from the head unit or local.

Just read your update post, my advice is late but still pertinent. Swap out the LC2I. If there is no warranty available, you can safely jump the remote turn on with some type of voltage reducer or protection circuit.

 

[bmeger]

I think I was mistaken when I said the amp turns on when the car is off. On the MTX amp, the power light is on (red) when the car is off. I have had this amp for over 3 years, in 3 different cars and it has always done this. I swapped out this amp recently for a Phoenix Gold Z1000.1, and the new amp's power light does not turn on when the car is off.

I'm assuming most people are familiar with the LC2i, but if not, it has a remote output on it. I have a wire running from the remote output on the LC2i to the remote input on the amp, as it was done at a shop and worked fine until recently. The amp no longer turns on when the car turns on. What I did was instead of running the remote wire from the LC2i into the amp, I ran the wire from my power cable in the amp into the remote input. This made the system run perfectly.

I'm almost certain now that the LC2i is the culprit, I am going to try to get it replaced. Any suggestions for a temporary remote in the meantime? Keep in mind I'm a rookie at this kind of stuff.

 

[What was that? 10+ year member]

I did give you a temporary solution. Jump the remote wire off the power but put a fuse inline. You can purchase little inline fuse holders at any auto parts store. Just make sure you get a 1 amp fuse. .5 amp is better.

Cooper Bussmann/ATM in-line fuse holder BP-HHM-RP at AutoZone.com

 

[bmeger]

Won't that make it so the amp never shuts off?

 

[big scott]

yes it will keep the amp on, so dont do that.

you can wire it to a switch. you can wire it to the fuse block so you get power when key is on. thats the best way.

thats if your remote turn on is not working.

 

[What was that? 10+ year member]

Won't that make it so the amp never shuts off?

Good point.

Didn't think of telling you that because I install toggle switches to the sub amps in every install I ever do. So it's second nature to me having a switch. I like being able to shut it off at certain times. At least someone is paying attention.

 

[bmeger]

Thank you guys for the help, I appreciate it.

One quick question. Since I have wires coming from my rear speakers into my LC2i, would it be unwise just to run a wire from one of the positive speaker terminals in the LC2i to the remote? I haven't heard of anyone doing that so I assume it's a bad idea.

 

[What was that? 10+ year member]

It is a bad idea. Best - what Big Scott said. You could probably permanently install a toggle switch up front in a discrete location in less than an hour. I just re-ran the one in my Silverado in 15 minutes. It will take some small gauge wire but that will be in the same isle as the toggle switch and fuse holder //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif. It won't cost you more than $20 and an hour for all the things to do it the right way. This will allow you tap any acc fuse and add a low amp fuse for the remote turn on.

Cooper Bussmann/ATC fuse tap BP-HHA-RP at AutoZone.com. T