So basically I let a friend borrow my car and while he was using it he messed up the trunk latch and when he couldn't fix it he tied an extension cord around my subwoofer and box and held the trunk down with it. When he drove it back to me he played the music all the way up and when I got it back my subwoofer wouldn't play. I figured it was the woofer being held back while trying to play but then I tried another sub on it and it still wouldn't play so I tried another sub and again it didn't play. What could it be causing my issues. What could I do to diagnose my issue. The light on the amp goes on and it looks like everything is working. any help would be awesome. Thanks.

sounds like you shouldnt loan your car out anymore lol.

Sounds like the problem is the amp, check all connections..im sure there is more that you can do, people will guide you here in this thread im sure.

Ask him what happened when it stopped playing. He had to have noticed it.

Sounds like the sub is not the issue. You have a start. Make sure all the connections on the amp are secure. Then try plugging in a different source to the amp, like plug in an mp3 player straight to it.

Sounds like you should see if your rca's are plugged in!

Less likely, the speaker wire came loose somewhere. However, anything can and will happen.

Something had to come undone. But take this advice If he's treating your car like that he definantly shouldnt be touching your car audio equipment

How would I go about plugging a different source into it. and how would I check the RCAs and how do I tell the two ends from each other.

When he means source he's talking about trying a radio station, a usb mp3 player, or an ipod, or plugging a ipod or mp3 player into the Aux port

No, I want him to take the head unit out of the whole equation first. Go to radio shack and get a headphone jack to male RCA adapter. Then plug your mp3 player into the amp with that.

What do you mean tell the two ends on the RCA from each other? One end goes to the head unit, the other to the amp. The two leads are just right and left channel signals, and they're color coded blue and black. Doesn't matter which one you plug into which channel.

Ok I took the rcas out n plugged in my mp3 player still nothin comin out. Any more ideas how wud I pull my head unit out to check the connection there? I mean if the amp was broken would there be some kinda sign to show it was broken.

Sounds like the amp is at fault then. Try putting a friend's amp in place of yours to see if it works.

Is the amp even coming on? I saw no mention of any LED indicator, or mention of the amp in protect mode, or any other such thing. This is such a simple thing to look for I can't believe no one even asked.

I see you have 2 amps. I assume the front stage amp is coming on. How are the remote turn ons wired? Do you have a relay or did you daisy chain them, or did you run 2 separate leads from the HU?

Does the sub work when you have the radio turned on? Not the CD player or what not, but the FM radio...

Yes the amps light does come on, I mentioned that at my first post. How would I check the protect light. I haven't tried it with the radio so I'll check.

My bad, I read someone else's sig. What amp, what sub, and what else is in the system? Some amps have dual LEDs for the power and protect, others have a single with 2 colors, green for power on and red for protect mode. Did you check for power at the remote turn on, and for main power? We need to be sure that it has not popped the fuses for the remote and the main power.

Its an alpine type R on a alpine mrp-m500. I mean to be honest its all coming out soon I just want to fix it in order to be able to sell it and stuff.

You need to get a test light or a multimeter and check both the main power cable, and the remote turn on lead. If using a voltmeter, select DC Volts, and select the setting that will allow you to test for roughly 12 volts. You need to be sure the amp is being turned on and is getting the juice from the main power cable. If either is not showing ~12 volts you need to check the connection at the amp, and check the fuses.

Then check to be sure that the RCAs are delivering signal with a multimeter. Select AC Volts and try testing at around 5 volts. You need to be sure that the amp is receiving the signal it needs to amplify for output to the sub. If there is no AC voltage, check the HU to ensure that the subwoofer out didn't get turned off on accident.

Finally, after all this has been checked, hook the multimeter across the speaker terminals and set it to AC volts and test it at around 20 or 30 volts. If the amp is getting turn on power and the main power is being supplied, and you know that the amp is seeing the low voltage signal from the HU to be amplified, it leaves only 2 things, the amplifier or it's on board fuses. Check all fuses on the amp. This is, of course, assuming that the 3 subs you have tested in the system are not all blown... clearly this is not very likely

Edited July 10, 201015 yr by sandt38

So I checked all the power and what not and the main power cable and remote turn on lead are both registering fine. The RCA cables however are not registering anything. The bitch is that I cant figure out how to get to the back of the head unit to see if they are unplugged. It doesn't just slide out with din tools I think I need to take off some paneling to get back there. Are there any other fuses other than the two 30's on the back of the amp i need to check because both of those are perfectly fine.

If your not getting input voltage it will be the HU and/or RCA's.

go through the menus on the HU and turn the subwoofer back on.

Im pretty sure I did that. I went to subwoofer and turned it up from ATT to 0 which is where I usually have my sub. I'll look but I don't think there's another way to alter the sub in there.

How did you test the RCAs?

The way you told me too. I used AC volts instead of DC and it read nothing. I tried turning the music up and down but nothing. I also tried it playiing a cd, the radio and my ipod. nada. I posted in a car specific forum hoping to get some info on how to get my head unit out but no luck so far.

What car? What HU? What terminals did you measure across?

Mercedes e320 with a shit sony head unit. I put the positive to the end of one of the RCAs and grounded the negative side. Is that the wrong way to do it. That method seemed to work for the power and remote cable.

You need to get a test light or a multimeter and check both the main power cable, and the remote turn on lead. If using a voltmeter, select DC Volts, and select the setting that will allow you to test for roughly 12 volts. You need to be sure the amp is being turned on and is getting the juice from the main power cable. If either is not showing ~12 volts you need to check the connection at the amp, and check the fuses.

Then check to be sure that the RCAs are delivering signal with a multimeter. Select AC Volts and try testing at around 5 volts. You need to be sure that the amp is receiving the signal it needs to amplify for output to the sub. If there is no AC voltage, check the HU to ensure that the subwoofer out didn't get turned off on accident.

Finally, after all this has been checked, hook the multimeter across the speaker terminals and set it to AC volts and test it at around 20 or 30 volts. If the amp is getting turn on power and the main power is being supplied, and you know that the amp is seeing the low voltage signal from the HU to be amplified, it leaves only 2 things, the amplifier or it's on board fuses. Check all fuses on the amp. This is, of course, assuming that the 3 subs you have tested in the system are not all blown... clearly this is not very likely

what he said get a meter an check everything an maybe go an un hook everything an wire it all back up

So I looked up how to properly check the voltage of the RCAs and I still got nothing from them. However I also tried to get a reading off of a friends and still got nothing. I also tried plugging his RCAs into my amp and still nothing played. So at this point I'm assuming that my amp is fried. Kind of a bummer. I'm going to pull my buddies amp out of his car and put it in mine just to make sure but we'll see. Thanks a lot guys I learned a ton trying to get this fixed so its not a complete loss.