Has anyone got a relay that fires something (footwell lights for example) whenever the dome light is on.

I did some major digging around last weekend and am left scratching my head.

The wires that go into the dome all appear to be switched negatives, so the longest solution might be to run taps off them each with a diode and wire them to the negative of the relay switch.

Looking for a simpler solution I looked into whether you could actually solder into the circuit board either side of the actual bulb, thinking that this would be easy. Only to discover that the when the bulb is not on both sides actually read positive current (???) only when you switch it with either the dome switch or one of the 4 other switching actions (doors, locks etc) does it turn into a ground.

It's additionally confusing as there appears to be some circuitry that makes makes the fade actually within the dome. All very confusing.

Anyone with better electrical experience fancy giving this some thought, or has anyone done it already.

Many thanks, Limey

 

*cough

No ones' done this ? I can't believe it.

 

OK hang on. the bulb is in the middle of a PCB and thankfully each side of teh contacts is HUGE, so it's easy to solder a new wire on.

If I solder a wire onto teh side that goes ground when the bulb is on, that and attach the other end of that wire to a relay with the opposite leg going to an always hot connection.

When the dome swicthes the bulb contacts from both live to live-ground it should fire the relay.

Does that make sense?

Why would you have a bulb that when off both sides are live ? Doesn't make sense to me?

And EE's fancy explaining this, I'm scratching this head good and hard.

 

so you basically wanted a positive trigger from the domelight turning on? Well the TC uses a negative trigger. Why not just use a relay ?

85- positive
86 - constant 12v
87 - constant 12v
30 output to power whatever youre lighting up.

Does that make sense?