Electrical Brain Teaser Question

[cg25713]

My truck is dual voltage and I have a 12v fuse box connected to my rear battery which powers three accessories. USB ports, a dome light and a Bluetooth speaker.

Is there any place to tie in the Bluetooth speaker and USB ports to an ignition switched 12v power source somewhere on the truck?

I'd prefer these go on with the ignition rather than having to switch them on and off with a switch.

Any guidance would be greatly appreciated. Thank you.

 

[TOBASH]

Sure.

Pretty simple.

Get a small power inverter and use the 24 Volt side.

OR:....

Use a 24 Volt relay and use it to turn on the 12 Volt side.

 

[AAVP7]

If your truck is an A2, you already have a 12 V relay. It switches 12 V power for the four-speed transmission when you switch main power to "run".

The relay is hidden behind the battery box . Check the A2 electrical schematics which plugs are switched 12 V

 

[Action]

If your truck is an A2, you already have a 12 V relay. It switches 12 V power for the four-speed transmission when you switch main power to "run".

The relay is hidden behind the battery box . Check the A2 electrical schematics which plugs are switched 12 V

I believe the TCM is always hot. At least one wire going to it is.
You can open the unused oulet on the front and put a multimeter in A (ground) and D (power) to verify.

 

[cg25713]

Thanks for all the input. My truck is an M1152A1. I think there is a 12v relay. I will check for that and also test the accessory outlet and tcm for 12v as well. These are the hints I was looking for. I'll let you all know what I find for future reference. Thank you.