Amp turning on for a second then nothing

[Karl Winslow]

Whats up guys.

My sub amp stopped working today. When I turn the car on the leds on the amp light up for a second then shut off.

I did a search on here and tried to troubleshoot the problem

the power and rem wire are both reading 11.5 volts when testing with a dmm.

I checked all the fuses on the amp and they look fine.

Any suggestions would be appreciated.

Im thinking maybe the amps blown but cannot figure out why the leds on the amp turn on for a second.

Thanks in advance.

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[Einzee 10+ year member]

The brief moment when the Amp lights up is the start of its internal "Power up/Self test" sequence that tells the Amp either to run or shut down. If all is well with the "Self test" then the Amp will complete the test and turn on. If there is a problem detected (as in your case) the Amp will not complete the test and instead will shut down.

 

[Karl Winslow]

Any idea what i should check next. Everything was working fine till yesterday.

It's getting power, the rem wire is getting power as well. I checked the ground with a dmm.

Ive had the amp for over two years and never had a problem. However i just moved it about a week ago from my old vehicle to my new one. It worked fine in the new vehicle for about a week then yesterday just stopped working...

 

[Torgus 10+ year member]

disconnect whatever speakers it's powering and see if it still shuts off. also it should read higher then 11.5.

 

[loopkiller 10+ year member]

Whats up guys.
My sub amp stopped working today. When I turn the car on the leds on the amp light up for a second then shut off.

I did a search on here and tried to troubleshoot the problem

the power and rem wire are both reading 11.5 volts when testing with a dmm.

I checked all the fuses on the amp and they look fine.

Any suggestions would be appreciated.

Im thinking maybe the amps blown but cannot figure out why the leds on the amp turn on for a second.

Thanks in advance.

You either have a defective alt, low batteries, or both if you are only seeing 11.5v at the amp without a load. Obviously you have no load because the amps are not turning on. Is this 11.5v with the engine running?

Another possible issue is a partially blown fuse. If you are using AGU (round glass) fuses, they can partially blow and pass partial voltage. Check your fuses.

 

[Karl Winslow]

You either have a defective alt, low batteries, or both if you are only seeing 11.5v at the amp without a load. Obviously you have no load because the amps are not turning on. Is this 11.5v with the engine running?
Another possible issue is a partially blown fuse. If you are using AGU (round glass) fuses, they can partially blow and pass partial voltage. Check your fuses.

Ok i just checked it again. the power is reading 12.9v with the car running and 11.9v without the car running.

THat should be enough right?

What else could i check?

 

[stangman67 10+ year member]

12.9 with your car running is still too little. Should be seeing around 14.0. The amp should still be working, this is just a side note

 

[Karl Winslow]

12.9 with your car running is still too little. Should be seeing around 14.0. The amp should still be working, this is just a side note

with the car running its reading 14v at the battery. 12.9 in the trunk. still I would think that would be enough to run the amp. Also I cannot figure out why it just stopped working all of a sudden.

 

[Torgus 10+ year member]

that's alot of voltage drop...

try another amp?

 

[loopkiller 10+ year member]

with the car running its reading 14v at the battery. 12.9 in the trunk. still I would think that would be enough to run the amp. Also I cannot figure out why it just stopped working all of a sudden.

OP can you tell us what type of wire you are running and any device between your front battery and the amp where you are getting the low reading. There must be an isolator or a very bad piece of wire in between. For the life of me, I cannot figure out how you could be seeing a voltage drop of that size in the length of a car.

that's alot of voltage drop...
try another amp?

I don't think he is even running any audio. These are no load voltages. I don't think the amp is the problem.

But to make sure, you can simply remove the ground wire from the amp and test the voltage to see if there is some sort of short in the amp that is drawing down your voltage.

 

[Karl Winslow]

OP can you tell us what type of wire you are running and any device between your front battery and the amp where you are getting the low reading. There must be an isolator or a very bad piece of wire in between. For the life of me, I cannot figure out how you could be seeing a voltage drop of that size in the length of a car.


I don't think he is even running any audio. These are no load voltages. I don't think the amp is the problem.

But to make sure, you can simply remove the ground wire from the amp and test the voltage to see if there is some sort of short in the amp that is drawing down your voltage.

The amp is a viper 1200.1 I believe. there is two fuses between the battery and the amp. (the second fuse was mainly used as a way to extend the 4 ga power wire to a longer length. ghetto i know). The power and ground are attached to a terminal that plugs into the amp itself. When testing the voltage I just unplugged the power and ground from amp and tested with a dmm at the terminal.

Since its reading 12.9v I was pretty sure that the power or ground should not be an issue since im getting the reading from the actual wires that plug into the amp.

The hu i recently installed is a pioneer f90bt. Im pretty sure that the hu is not the problem.

12.9 v is enough to make the amp turn on right?

 

[Karl Winslow]

Ok it ended up just being a bad ground. thanks for everyone's input.

 

[Torgus 10+ year member]

it's always something simple. glad you figured it out. grounds can be tested with a DMM too btw.