Linking headlights to interior light

[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?

[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.

[Meir]

the diagram for the light system is scattered over few pages, so i had to build a small puzzle. i also apologize for the low quality pictures taken with my cellphone.

first, this is where you can see the main power line (red wire) going into the switch.



if you follow the line to another page, you can see it goes to the current distributor.



the current distributor is basically a junction box from the battery positive lead, backed up by 80 amp fuses. it's located behind the ac air box.

now, this is the line that comes out of the switch (white/black), splits in two, goes to the fuse box, and on the other end, change colors and go to each individual head light.




on the other side of the fuse box the colors changes to yellow/black for the left headlight, and yellow for the right.

[Meir]

and here is the relay diagram.
obviously, the easy way is to locate the relay next to the light switch, and run a wire to the A pillar/cick panal to get to the courtesy light wire.
i will try and have a look this weekend and see where the best place to connect.