Linking headlights to interior light

[Meir]

Pwave is right.
I spent couple of hours last night, going over the diagrams looking for the headlights relay that doesn't exist
But just
I will post some diagram later on how I think it should be done, but basically you need to use a relay to jumper between the red and white/black wires, at the light switch.
Both are heavy gauge, so you will need a 30/40 amp relay.
The relay will be activated by the brown/yellow wire that comes from the BCM.
Since it is running all over the car, it can probebly be located at the ckick panel/ fuse box area. Same goes for the wire that comes from the light switch. It goes into the fuse box, and comes on the other side as yellow/black.
Obviusely you need to connect before the fuse.

[geraintthomas]

Originally Posted by Meir

Pwave is right.
I spent couple of hours last night, going over the diagrams looking for the headlights relay that doesn't exist
But just
I will post some diagram later on how I think it should be done, but basically you need to use a relay to jumper between the red and white/black wires, at the light switch.
Both are heavy gauge, so you will need a 30/40 amp relay.
The relay will be activated by the brown/yellow wire that comes from the BCM.
Since it is running all over the car, it can probebly be located at the ckick panel/ fuse box area. Same goes for the wire that comes from the light switch. It goes into the fuse box, and comes on the other side as yellow/black.
Obviusely you need to connect before the fuse.

Thank you

My only concern is that I use HID's, and the courtesy light uses a dimming feature to turn itself off. I wonder how that would affect the HID's - I'm hoping they'd just turn off once the voltage goes under a certain amount.

[Meir]

Originally Posted by geraintthomas

Thank you

My only concern is that I use HID's, and the courtesy light uses a dimming feature to turn itself off. I wonder how that would affect the HID's - I'm hoping they'd just turn off once the voltage goes under a certain amount.

well, the courtesy light will not be connected to the low beam circuit.
it will activate a relay that will switch the lights on and off.
so when the courtesy light will dim out to a certain level (in voltage), the relay will interrupt the lights circuit instantly.
the relay i tested disconnects/reconnects at 3-5 volts range.
here is a quick video i made.
https://youtu.be/mOkvLh2l1fw
pay attantion to the clicking noise coming from the relay, once the lights dimm out at around 3-5 volts
ignor the first click sound that is coming from the power supply.

[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.