Amplifiers not switching on

[Eklipze3k]

Riddle me this! The remote output of the HU sends 12v, until it's connected to an amp, and then that changes to 5.13v. The amplifiers don't switch on though, I'd have thought the remote wire should be sending a constant 12v? As soon as I disconnect the cable from the amplifier, the reading goes back up to 12v. Is this maybe some kind of protection circuitry in the amp, could it be that the fuses have blown? I was going to check the fuses but it started raining and they're hidden under false floor :/

Cheers!

 

[Eklipze3k]

Well it's not a fuse issue as I've wired up the remote to an ignition live and it works fine. Rather than faffing about trying to get the remote to work properly I've just added a switch in the ignition source but still curious why that would happen ...