I've got a 2011 Fit Sport, but haven't shelled out for a shop manual. I am wondering if anyone knows where in the vehicle the device that reduces the voltage to the headlights when they are in DRL mode is.

It might be referred to as a dimmer, voltage clipper, voltage regulator, DC/DC converter or something like that.

I saw what looked like a wiring diagram here:
Wiring Diagram Index

But I think it's for older models. The link to section 4 seems to insinuate that it's part of the combination lighting switch in the steering column, but that seemed like an awfully strange place to put it.

Anyone know more definitively?

 

i donno but what are you trying to do?

just wire up new lights on them? if so, how about you pull from the DRL fuse #15 and relay it?

 

I have a set of LED H11 bulbs in my fog lamps. They aren't really bright enough for true fog lamps, but they make great DRLs. What I was thinking of doing was putting a toggle switch in to either allow current through the high beams and into the dimmer module (ie normal Fit DRLs) or divert current through the LED fog lamps to chassis instead of through the dimmer.

At 12v the LEDs only pass <0.5 amps which won't cause the high beams to light, and the voltage drop through the unlit bulb is very low, so I can leave the existing DRL circuit pretty much intact.

But this is all 1000x easier if I can easily access the wire between the high beam and the DRL dimmer.

 

try this... pull the #15 fuse, then add a relay to the LED fog using the common wire of the headlight as the control circuit. the relay has to be the type that connects when the control is OFF.

And if you want a switch, add it to the #15 fuse slot... switch it on for normal DRL, off for the LED.

 

The wiring diagram you linked to doesn't have any DRL system. The dimmer in the combination switch is just the normal headlight dimmer (for high beams vs. low beams). The DRL dimmer may at least partly be built into the ECU; I think I remember reading here that it's a sort of square wave/PWM signal (which should work OK for driving a LED at reduced brightness if that's what you're after). It would be a lot easier to work out a plan with a wiring diagram that included the systems in question.

I think it might be most fruitful to investigate the relays for the lights; it appears to me, at least on my '12 model, that they're probably located in the little plastic box underneath the left light cluster attached to the side of the battery holder. You could probably work out which one does what by listening to them click through a crude sort of stethoscope while somebody manipulates the light switches and DRLs and so forth. (The stethoscope could just be a length of stiff wire with one end against the relay you're listening to and the other against a jar lid or plastic cup or something similar over your ear. There's no need to abscond with one from a doctor's office or anything like that.)