T25 radio wiring help needed

[paulwilde]

Hi fellow Camper owners!

I recently got myself a T25, love it to bits already.
I am currently replacing the radio, although the current radio is also an aftermarket one.
I am having a problem though, I have discovered that both the Battery +12V and Swich +12V cables have been wired together, meaning the radio stays even when the key is out of the ignition.
I have done some investigatory work and discovered this:-

(Yellow)Battery +12V cable from ISO wiring adaptor and (Red)Switched +12V cable from ISO wiring adaptor wired together into one side of a wiring coupler.
Thick Red and Thin Red cables from existing wiring loom wired together into the other side of the same coupler.

This makes the radio work, but of course the radio stays on regardless of if the key is in the ignition or not.
I have discovered that when the Thick Red cable is connected on its own to the Yellow and Red ISO wiring adaptor cables, the radio continues to work as always. This to me says this Thick Red cable is coming from the battery.
So, I wired the Yellow cable to the Thick Red cable - and this to me seems correct, the 12V+ Battery current direct to the battery cabling on the ISO wiring adaptor, of course this won't power the radio on but is hopefully powering the radio clock and memory.
What I did next was to connect the Red ISO wiring adaptor cable and Thin Red pre-existing cable together as I had assumed that the Thin Red cable must be for the switched +12V cable, what I assume is to be via the ignition key switch(?). But, nope, this doesn't work, the radio will not power on even with the engine running - although hopefully the radio clock and memory is still being powered by the battery.
So, what I need to find out now is what cable is the one I need to connect to the +12V switched cable of the ISO wiring adaptor and where would I find it?
Also, what on earth is this Thin Red cable? It was connected before, but removing it doesn't seem to have made a difference.

I have a multimeter, but to be honest I'm not sure exactly what I should be testing for and where, any help would be greatly appreciated.

Thanks,
Paul

[chewbacca]

I'm sure someone will be on with a detailed reply, but basically, unless your ignition switch has been modified there's no feed for the radio.

You either wire it so it's always on, only powered off with the head unit power button.
Put in a separate switch that can act as the ignition key switch.
Wire it to ignition is another option, but not great if you listen with the engine off a lot.

Hope that helps a little.

[boatbuilder]

I was having a look at wiring up my new radio as well.
Good point about listening to the radio with the ignition off.
Also was wondering where you'd attach the illumination wire as that would be a good feature to have.

[paulwilde]

Thanks for your reply chewbacca.

Never considered the possibility that T25's dont have a feed for the radio! Maybe I'm used to more modern cars!
Thank's for your idea's. I don't want to wire it up so it is always powered and switch off manually, as the radio has Bluetooth and a remote control, I am concerned that the IR receiver and BT will still be powered when the radio is 'off' and will drain the battery.
I do however have a switch on the dashboard that isn't attached to anything, just a simple toggle switch, I suppose I could attach a secondary cable to the battery feed of the radio (Thick Red cable fro my previous post) and link through this switch to attach to the main radio power? Does this seem logical or am I being stupid?

Also, I hadn't even considered the Illumination wire, what does this do exactly?

Thanks again for your help.

[boatbuilder]

Illumination senses whenever you turn your headlights on and automatically dims the radio display so it doesn't blind you while driving at night.
Can't imagine that the Bluetooth etc would still be on when the radio is powered off?...my radio has BT and an IR remote as well. You could fit a switch but unless you didn't drive your van for a month or two it would hardly drain the battery?

[paulwilde]

Thanks boatbuilder.

I accidently left the previous radio front fascia connected for a couple of days and it drained the battery, so a little concerned. I probably have a dodgy battery as well which I will be replacing, but just wanted to have the choice of leaving the radio definitely on or definitely off.

I'll prob connect it to the switch, mainly because I just want a use of that switch on the dash.

Thanks for all your help!

[chewbacca]

Sounds like you're sorted!