head unit only powers up for 2 seconds?
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=126032
Printed Date: May 24, 2024 at 12:24 PM
Topic: head unit only powers up for 2 seconds?
Posted By: 4pac
Subject: head unit only powers up for 2 seconds?
Date Posted: February 05, 2011 at 5:08 PM
Hi all. please forgive me if I,ve posted in the wrong section of the forum,
A friend of mine bought a new stereo for his Audi A3. He took it somewhere to be fitted and the geezer at the garage said the new head unit powered up for a short period then switched itself off. His conclusion was that the head unit was knackered so it got sent back to the supplier. The unit was tested at the factory and worked perfectly.
I went round to my friends today & tried to refit the "original" head unit but the same thing happened, it would power up for a couple of seconds then switch off.
If I disconect the power lead and wait for a few seconds, when i plug it back in the head unit will power up again but only for 2 seconds.
Does anybody have an idea what could cause this?
(I,m not sure if the bloke at the garage altered any of the wiring, would the head unit do this if it wasn,t earthed I wonder?)
Thanks for any input you could give,
Andy
Replies:
Posted By: i am an idiot
Date Posted: February 06, 2011 at 7:47 AM
No earth would = no power up at all. You will need to get a volt meter and verify that the unit is getting adequate power on both the constant and the switched power wires. And also check earth as well.
Posted By: 4pac
Date Posted: February 06, 2011 at 10:25 AM
Thanks mate I,ll nip out and have a prod round at the wires, Cheers.
Posted By: 4pac
Date Posted: February 06, 2011 at 7:38 PM
Had a poke round with the multimeter & I,m geting a contsant 12volts from the wires, think the original head unit must be damaged thats why it keeps shutting down. I get the new head unit backtomorrow, hopefully this will work ok. fingers crossed.
Posted By: 4pac
Date Posted: February 06, 2011 at 7:53 PM
PS
Well done guys, I entered the same problem on 2 forums & you were the first to reply. I know where I,ll come back to in future.
Posted By: 4pac
Date Posted: February 06, 2011 at 7:54 PM
MINT 
Posted By: i am an idiot
Date Posted: February 06, 2011 at 8:21 PM
All modern day radios need 2 power sources. The yellow wire of the deck should receive constant power. The red wire of the deck needs to be supplied with 12 volts only when the key is on.
Posted By: 4pac
Date Posted: February 07, 2011 at 6:35 AM
The car only has one wire that supplies power & that power is constant, there is no wire from a swiched power source. (I also thought that was strange)
Would it be ok to wire both the red & yellow wires to the constant power source?
Posted By: KPierson
Date Posted: February 07, 2011 at 7:37 AM
If you wire red and yellow to constant power the radio will not shut off with the ignition. You'll need to manually turn it off every time the car is turned off. Not a good solution. If there isn't a switched ignition feed in the harness then you would be best off to make one from the ignition wiring. What year is the A3?
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Kevin Pierson
Posted By: 4pac
Date Posted: February 07, 2011 at 7:52 AM
Its a 2004 mate.
Posted By: d6-karl
Date Posted: February 09, 2011 at 5:07 PM
There will only be one live wire for that Audi as the original stereo is triggered using a digital signal, u can connect both to the perment but it's not great, u can use a product from connect 2 called a ignigen which will trigger when the alternator is running to create a fake ignition wire, alternately u could use the cigarette lighter or go to the fuse box and use an empty accessory socket on the fuse box, make sure u use a fuse inline as close to the source as u can !!!!!!!
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D6-In Car Solutions
Posted By: 4pac
Date Posted: February 10, 2011 at 4:07 AM
Thanks mate, got the head unit back yesterday & wired the baby in by just using snipped wires & insulation tape. Everything's working ok so I,ll nip out & get a fuse lead & some connector blocks later.
Posted By: 4pac
Date Posted: February 10, 2011 at 4:08 AM
Thanks for taking the time to reply.
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