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Switched 12V in engine bay?

T

tabugman

New member
Location
Sweden
Hi!
I've just installed some aftermarket LED DRLs on my Golf 1.2 TSi. Normally the control box (relay) of such lights is just connected to
- battery +
- ground
- low beam 12V (in order to dim the DRLs when you turn on the low beam). I'll use a t-tap connected to the low beam 12V cable on the headlight harness for this.

Unfortunately the control box that came with my lights doesn't seem to detect when the engine is started, which means the DRLs are always on, even if the car is completely turned off. This means I need to find 12V that's switched on with the ignition.

My car is a European version with halogen headlights if that matters.

To make a long story short: does anyone have any ideas on where to find switched 12V in the engine bay? :)
 
Last edited:
T

tabugman

New member
Location
Sweden
I brought out my volt meter and went over the fuses in the engine bay, but was unable to find switched 12V unfortunately. :(

Might be I'm a noob though.
 
N

nobbo

Passed Driver's Ed
Location
HULL
i have some SMD lights i tried fitting as DRL but also couldnt find an ignition live fuse. only other option is to scotch lock the live wire to the DRL wire from the headlights
 
T

tabugman

New member
Location
Sweden
nobbo said:
i have some SMD lights i tried fitting as DRL but also couldnt find an ignition live fuse. only other option is to scotch lock the live wire to the DRL wire from the headlights
Click to expand...

Yep. It seems there are two options:
1) Run a 12V switched live from the fuse box under the the steering wheel. This means going through the firewall somehow.
2) Tap into the factory DRL (the wire feeding the smaller filament inside the H15 DRL/High beam lamp).

The latter was suggested to me today by a local VW technician. The only problem I have with this approach is that the LED DRLs would go completely dark when I turn on the low beam headlights, since the factory DRLs are turned off at this point.

The relay that came with the lights have three cables (apart from the ones going to the LEDs themselves) that are supposed to be connected like this:
- Red: Swithced 12V
- Black: Ground
- Yellow: Low beam (in order to detect when the low beam being lit -> dimming the LEDs)

What you and the technician suggest:
- Red: Factory DRL 12V
- Black: Ground
- Yellow: nothing
 
M

misaka

Ready to race!
Location
Staten Island, New York
tabugman said:
Yep. It seems there are two options:
1) Run a 12V switched live from the fuse box under the the steering wheel. This means going through the firewall somehow.
2) Tap into the factory DRL (the wire feeding the smaller filament inside the H15 DRL/High beam lamp).

The latter was suggested to me today by a local VW technician. The only problem I have with this approach is that the LED DRLs would go completely dark when I turn on the low beam headlights, since the factory DRLs are turned off at this point.

The relay that came with the lights have three cables (apart from the ones going to the LEDs themselves) that are supposed to be connected like this:
- Red: Swithced 12V
- Black: Ground
- Yellow: Low beam (in order to detect when the low beam being lit -> dimming the LEDs)

What you and the technician suggest:
- Red: Factory DRL 12V
- Black: Ground
- Yellow: nothing
Click to expand...

You could also dual tap the red wire, 1 connection to factory DRL, 1 connection to your city light / side marker light, then it's on no matter what.
 
T

tabugman

New member
Location
Sweden
Thanks for the reply. :)
I connected the LED's plus to the left factory DRL just to find out that VW had decided that it's a good idea to cut the power to left DRL when you use the left indicator (and vice versa) :)

This means that the LEDs currently go out when I turn left...

I decided to bite the bullet and order a relay that automatically senses when the ignition comes on. If that fails (as I almost expect it to at this point), I'll go through the firewall to find a proper switched live.
 
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