Hey guys. So as I'm about to wire in my new alarm. Iv had an idea that kills 2 birds with one stone regarding my positive interior light. My door switches for the alarm go to ground when the doors open. Exactly what I need. My interior light is powered by a switched live that is permanently grounded at the light. I want the light to come on when the doors open and the alarm also want to connect to something that goes 12v when the interior light is on. So I have come up with the following.

Ignoring the letters as there for me to know where to wire in the alarm.
1 is the door switch, 2 is the current switch to turn the light on, 3 is obviously the light and I hope you recognise my doodle as being a relay under the light.

Some might say why not rewire the light to ground on the door switch but it would need alot more wiring than my idea requires as I can use a 12v micro relay behind the dash where all the wiring already bunches together.

I'm hoping someone can confirm my diagram isn't faulty

Assuming G is the other door switches and Y is for the alarm that would appear to work as you want.

Glad to hear it

I considered doing this, but in the end settled for wiring in an independent light switch in the rear door trim, so I can get stuff in and out the back without having to turn the light off from the front. You might not always want the light to come on when you open the door.

Well I never do anything that requires discretion, plus with a noisy diesel I don't think discrete is even possible haha

But thanks for confirming my circuit diagram