Linking headlights to interior light

[geraintthomas]

Just a thought I had.

How easy would it be to wire the headlights to come on when the interior light comes on? A lot of modern cars now have headlights that turn on when you unlock the car, but also when you open the door at night. If the headlights were linked to the interior light, it would give the same effect.

Obviously I'd still like to turn them on as normal, but I just want the courtesy light to turn them on too.

Hard to do?

[JayG]

I imaging with a few relays and the wiring diagram you could .

Might be easier for you to move the steering wheel to the correct side (left)

[geraintthomas]

Well, it was kind of a question towards people who would possibly know how to do it haha.

And I'll keep the steering wheel on the right side thanks very much! (Right in both senses of the word )

[Meir]

that is very interesting mode.
it should be fairly easy to achieve with 1 relay connected at the back of the fuse/relay box.
the only challenge is to locate the correct wires, but they both should be there.
what year is your box?
maybe i can have a look at the diagram for you.

[geraintthomas]

It's a 2003 facelift Boxster S.

Thank you I think it'll be a nice modification. Because modern cars have a feature at night when you open the door the headlights come on, or when you unlock the car it'll come on, etc. Just linking it to come on with the interior light will be all that's needed to do it

[Meir]

Originally Posted by geraintthomas

It's a 2003 facelift Boxster S.

Thank you I think it'll be a nice modification. Because modern cars have a feature at night when you open the door the headlights come on, or when you unlock the car it'll come on, etc. Just linking it to come on with the interior light will be all that's needed to do it

Yes I totally get it.
I might even do it on my 02 996. Should be same electrical system.
What did you had in mind? Activate the parking lights, or the main?

[thstone]

This should be fairly easy.

The headlights are powered from a relay that is activated by the switch. All you have to do is activate the relay. One way to do this would be to tap into one of the wires powering the interior lights and run it to the correct pins on the headlight relay. Thus, when the interior lights turn on, the headlight relay will be switched on and then the highlights should turn on.

This is very similar to the hack that I posted to control the engine compartment fan using a manual switch (http://986forum.com/forums/diy-project-guides/60239-engine-compartment-fan-manual-switch.html).

What I'd have to check is what type of relay the headlights use (standard Type 53 or something else) to figure out which pins to jumper and if the 2003 S is wired close to the same as the 97-99 base that I have - but the principle should be the same even if the exact details are different.

[stelan]

But your wife will notice when you sneak out at night and that is a big no, or is int?

[particlewave]

Originally Posted by thstone

What I'd have to check is what type of relay the headlights use

None.

A switch and some fuses is all (this is why our switches are so prone to failure).

[geraintthomas]

Originally Posted by particlewave

None.

A switch and some fuses is all (this is why our switches are so prone to failure).

I would have thought if there's anyone here that could do it, it would have been you any idea on how this could be done?

[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.

[thstone]

Originally Posted by particlewave

None.

A switch and some fuses is all (this is why our switches are so prone to failure).

Whaaat? There's no headlight relay?

I thought there had to be one, but didn't have time to check the wiring diagrams.

Sorry for the misdirection and thanks for the correction.

[geraintthomas]

I know there's a hack to turn the fog lights on with the car by using a jumper between fuses. Maybe a similar approach?

[geraintthomas]

This is looking VERY promising! Be sure to write a guide!

[particlewave]

If your courtesy lights dim out, you'd need a controller circuit to power the relay. Otherwise, the relay would chatter as the voltage drops to near the relay solenoids threshold. This would cause premature failure of said relay and wreak havoc on the HID ballasts and bulbs.
You'd need a micro controller that applies/cuts power to the relay at a predetermined threshold.

Even with the controller, they'd want to come on and off a lot and would not be good for the HIDs. Incandescent fog or parking lights would be better.

[Meir]

Originally Posted by particlewave

If your courtesy lights dim out, you'd need a controller circuit to power the relay. Otherwise, the relay would chatter as the voltage drops to near the relay solenoids threshold. This would cause premature failure of said relay and wreak havoc on the HID ballasts and bulbs.
You'd need a micro controller that applies/cuts power to the relay at a predetermined threshold.

Even with the controller, they'd want to come on and off a lot and would not be good for the HIDs. Incandescent fog or parking lights would be better.

Advise taken.
On the bench the relay acted fine when I simulated the voltage drop, but I will test it on the actual wire in the car.
Agree on the fog/parking lights instead of abusing the litronics (in my case).

[geraintthomas]

Any news on the testing side?

[Meir]

Originally Posted by geraintthomas

Any news on the testing side?

Didn't get a chance to look at it this past weekend.
Hopefully later this week, as I have to do some other electrical projects on the car.
I already have an OEM relay holder, and just got these today
https://www.amazon.com/gp/product/B01G7KKBYG/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
So I can replace the wires with thicker ones.
Also have this on the way
https://www.amazon.com/gp/product/B00ZYXHR6S/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
To remove the existing pins from the relay holder.
The idea is to use the correct wire gauge and locate the relay on the relay carrier above the fuse box.

[Meir]

so i spend some time today going over the diagrams, and looking at the fog light circuit.
it looks like the lights should be isolated from the switch before power is directed to them. otherwise, the light switch will be probably damage.
not a big problem, will just have to use a 5 legs relay.
i also tested the wire that comes from the BCM, and basically going to trigger the relay.
wanted to confirm that the relay will not chatter when the power gradually drops, and the lights are dimming out.
i made a short video of the process.
https://youtu.be/jPfQFOOu45c
after filming the video, i thought it will be a good idea to add a timer to the setup, so i will be able to control the length of the "On time" after locking the car.
so i will probably get something like that, and also use it as the relay.



might even go pro and add a Photoelectric Switch :dance:
Zing Ear SNR100A Photo-Electric-Resistor-Cell Light Detector Sensor Switch 25W | eBay