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DarquePervert · 04-08-2007, 06:41 PM

First of all, a simple light is a lousy method of testing. Get a digital multimeter. An electronics shop will have one for under twenty bucks. A light is not going to tell you if the current on that wire is dropping to 0 volts or just less than what it should.

Second of all, most headunits have two power wires. One is constant 12v and one is switched 12v. The constant 12v keeps the memory and clock of the unit and will allow you to eject a CD with ignition off (on some units). The switched 12v line will power the unit when the car's ignition is turned on.

Third, if that wire were broken, you wouldn't get current through it when the ignition was on.

Fourth, you can simply pull a wire through a rubber grommet in your firewall, although I don't think this is necessary. If you do this, you run the risk of having your radio drawing power all the time, even when the ignition is turned off. This will drain your battery.

It sounds to me as if the constant and switched power lines to the stereo are reversed. Either that or both of those lines are connected to an ignition-switched power line.
If you're not certain what you're doing, it might be a good idea to take it to someone does know what they are doing rather than take guesses or follow suggestions from random people on the internet who sound like they know what they are talking about (myself included). If your wiring is screwed, you run the risk of damaging equipment, shorting wires, starting a fire or possibly injuring or killing yourself or passengers.
None of us want to see any of those things happen.

Lastly...
Quit crossposting!

Moved to the Car Audio forum.

04-08-2007, 06:41 PM	#4
DarquePervert Neither darque nor pervert Join Date: Apr 2004 Location: In The Sticks near The 'Ham Posts: 12,063	First of all, a simple light is a lousy method of testing. Get a digital multimeter. An electronics shop will have one for under twenty bucks. A light is not going to tell you if the current on that wire is dropping to 0 volts or just less than what it should. Second of all, most headunits have two power wires. One is constant 12v and one is switched 12v. The constant 12v keeps the memory and clock of the unit and will allow you to eject a CD with ignition off (on some units). The switched 12v line will power the unit when the car's ignition is turned on. Third, if that wire were broken, you wouldn't get current through it when the ignition was on. Fourth, you can simply pull a wire through a rubber grommet in your firewall, although I don't think this is necessary. If you do this, you run the risk of having your radio drawing power all the time, even when the ignition is turned off. This will drain your battery. It sounds to me as if the constant and switched power lines to the stereo are reversed. Either that or both of those lines are connected to an ignition-switched power line. If you're not certain what you're doing, it might be a good idea to take it to someone does know what they are doing rather than take guesses or follow suggestions from random people on the internet who sound like they know what they are talking about (myself included). If your wiring is screwed, you run the risk of damaging equipment, shorting wires, starting a fire or possibly injuring or killing yourself or passengers. None of us want to see any of those things happen. Lastly... Quit crossposting! Moved to the Car Audio forum. __________________ SEARCH: It's how information gets found! How To Ask Questions The Smart Way [\|\|\|\|\|\|\|--] - 80% (I estimate completion in Spring '07) My Worklog Last edited by DarquePervert; 04-08-2007 at 06:43 PM.