Linking headlights to interior light

[Meir]

Originally Posted by jb92563

Just a related thought:

A 55w headlight draws about 4.5 amps each so without a relay, upgrading to a higher watt headlight bulb as some folks do will also shorten the life of the light switch (as well as burning the plastic lens).

You will need to put in a 10amp+ relay for the headlights that will now trigger from the light switch AND the courtesy light signal wire?

Wondering if the current will flow the wrong way and damage something if the signals are not isolated from each other?
Perhaps a couple diodes will prevent that possibility?

it will be no problem.
the added relay will act as the switch itself. no need to isolate anything, as the relay will imitate the switch.
you are right about the load though, that is way the switch is so robust and more have duty (compared to other cars that uses a light relay)and uses thicker wires. not that it really helps as mentioned by Pwave.
i have to admit i was surprize to find out that the light system do not incorporate a relay.
circuit diagram to follow in a bit.