dual head unit wiring

Hello all, this is my first post.

I have decided to replace my exisiting hu in my 2004 vauxhall vectra with a motorised tv head unit and a sony cd hu, finally linking the TV HU into a DVB Freeview box.

Took out the old HU and patched both harnesses for the replacement HU's into the Sony harness and plugged it all in. Sony HU worked perfectly until I connected TV HU then Sony unit died, no lights or anything but TV worked fine. Anyway used glovebox light feeds to power TV and exisiting radio feeds for CD so both work at the same time.

Question is can anybody explain why CD dies when taking feeds for both off radio feed as I would have prefered to have TV ignition controlled just like the cd.

Do I need to feed both via a Relay

Sorry but I dont have loads of experience in 12v wiing

You didn't hook the speaker outputs of both units together did you?  You won't be able to power your speakers with both units at the same time.  At a bare minimum you'll need to relay isolate your speaker outputs then have a switch to swtich between audio sources.

Otherwise, if you just hooked power up to both units they should work fine without a relay.

no Kevin, tv has rca outputs so wired in a fm transmitter and tuned a free station on the cd hu to receive signal.

the two seperate feeds seem to work fine so will probably leave as is

thanks

steve