GM 12V accessory connection

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=36394
Printed Date: May 13, 2025 at 7:17 PM

Topic: GM 12V accessory connection

Posted By: bigbass152
Subject: GM 12V accessory connection
Date Posted: July 29, 2004 at 10:49 AM

Question: Most new GM head units no longer get their 12 volts simply from the ignition switch. Instead the head unit will continue to operate after the ignition has been turned off.... and stay on until a timer triggers or a door is opened. It's a nice feature. I would like to drive my new amp's 12V relay with this signal.... but I can not find it (I have a 2004 C5 Corvette). Help would be very much appreciated.

Replies:

Posted By: kgerry
Date Posted: July 29, 2004 at 1:18 PM

this circuit at the radio is not controlled by a 12 v pulse or switched voltage... therefore you cannot "tap" into it to use it as a remote turn on for an amp.....

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Kevin Gerry
Certified Electronics Technician
MECP First Class Installer

Owner/Installer
Classic Car Audio
since 1979

Posted By: bigbass152
Date Posted: July 29, 2004 at 1:41 PM

Thanks for the reply Kevin. I am thinking now that my last chance might be the power antenna control (if there is one). When the head unit is powered on it must need to keep the antenna up.... by possibly supplying it a 12V signal. What do you think?

Posted By: sparkie
Date Posted: July 29, 2004 at 2:21 PM

If your Corvette is a convertible it will have a power antenna. Use the green wire at the antenna for an amp turn on wire.

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sparky

Posted By: bigbass152
Date Posted: July 29, 2004 at 4:10 PM

Wish I had a convertible. But I don't. Thank you for the reply! Think I'll have to stick to the 'ol accessory pickoff.

Posted By: sparkie
Date Posted: July 29, 2004 at 4:18 PM

The same wire can be found on the back of the radio. It is the wire that turns the BOSE amps on. Use a digital volt meter to find the wire as there is more than one green wire.

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sparky

Posted By: bigbass152
Date Posted: July 29, 2004 at 5:57 PM

Wow! Thanks. I can't believe there is still hope. I'll find it.

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