my sub doesnt work when the car is off

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=102023
Printed Date: July 13, 2025 at 4:42 AM

Topic: my sub doesnt work when the car is off

Posted By: still_walkin
Subject: my sub doesnt work when the car is off
Date Posted: February 09, 2008 at 3:23 AM

i have this friend of mine that has a 2005 scion adn the factory stereo is still present and he has wired an amp to the factory stereo . the question is when the car is in accesory mode (off) the subwoofer doesnt work it hits once then fades lower till you cant hear it at all any suggestions on whats wrong with it

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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"

Replies:

Posted By: DYohn
Date Posted: February 09, 2008 at 10:30 AM

What is the system voltage when this happens?

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Posted By: still_walkin
Date Posted: February 09, 2008 at 3:50 PM

I never put it on the voltometer but I asked him on his wiring and it all seems normal except his remote turn on. He didn't wire it to the anttenna he just found a wire that is hot when the ignition is on. So I don't kno if that can be the issue

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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"

Posted By: DYohn
Date Posted: February 09, 2008 at 4:58 PM

Yes, that can be the issue since many vehicles these days do not use a full 12V for trigger voltages. Check the voltage of whatever is being used for remote turn on. But, if the amp comes on for a second and then fades out it sounds to me more like crappy main voltage. If you want to run the system with the car off, you'll probably need a new battery.

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Posted By: still_walkin
Date Posted: February 09, 2008 at 5:35 PM

Thanks for yoyur help ill double check the remote turn on and the main 12v

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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"