After market headunit wont work? Symphony double din

[StevoS3]

Hey all, I recently bought a new headunit for my car (2002 S3 Symphony 2 * I think * Double Din)

I can seem to get any other headunit i try in the car to even turn on but when i put the oem one back in it turns on fine..

Anyone know what the issue is and how to resolve it?

Thanks.

 

[B5NUT]

My guess your missing a switched live wire, as the symphony turns on via can-bus messages.

 

[AndyMac]

Yes, you need to wire in a switched feed or just pair the ignition feed with the perm live, and turn the HU on/off manually