Pre wiring for satalite

[Clyro]

Hi, I have pre wiring for satalite but what to use it for a wifi router. There are 3 wires - green (ground) blue 12v (engine on) and red 12v (engine off) I initially wired to red and the discovered this switches off when engine running. How can I use the 2 feeds to provide a constant 12v supply as I want wifi on all the time?

 

[StratosFearXX]

A five pin switching relay would do it. Although the router would probably reboot every time it switched.

 

[Clyro]

Would 2 in line diodes work for each feed and spliced together?

 

[Clyro]

@Dellmassive can you help?

 

[Clyro]

Wow thanks for all your help, turns out I was using the green wire as ground but it was a D+ signal wire so this was 12v when engine turned on. The red was permanent 12v and the blue wire was the ground. So why I had the volt meter on green and red i was getting 12v engine off and 0v engine on. But blue and red 12v engine off and 14.5v engine on. Problem solved.