I'm wondering how my '09 Fit runs its DRLs.

Are they run at half voltage and when I turn on the lights, it bumps up to 12V+ or is there a special circuit in the bulb, or do they use Pulse Width Modulation?

I'm wondering because I'd like to run my "Angel Eyes" for my HIDs from the disabled DRL circuit, but if it doesn't supply a constant 12V, then that's impossible.

TIA for any thoughts/advice/tips!!

-Darryl

 

Practically speaking, if they're at any voltage other than 12V, PWM has to be used to step-down the voltage. I would get a digital multimeter and put it on the plug and see, probably the easiest way.

 

The daytime running lights system includes the MICU, the left and right high beam headlights, the parking brake switch, and the DRL indicator on the gauge control module. The daytime running lights operate with the ignition switch turned to ON (II), the headlights off (headlight switch OFF or in the parking position), and the parking brake released.

When the daytime running lights are on, the MICU turns the high beam headlight control circuit on and off (duty cycle), which provides a reduced voltage (approximately 4-8 volts) to the high beam headlights (via the No. 48 and No. 51 fuses in the under-dash fuse/relay box; the high beam headlights come on with reduced brightness. The MICU also sends a signal to the gauge control module, and the DRL indication is indicated on the gauge.

NOTE:

• The daytime running lights are disabled when the ignition switch is turned to LOCK (0). To keep the daytime running lights from coming on, apply the parking brake switch while the ignition switch is in LOCK (0) position. When you then turn the ignition switch back to ON (II), the daytime running lights will not come on until the parking brake is released.
• The headlights revert to normal operation when you turn them on with the headlight switch.

 

The image above is a VERY simplified version of the plug if you were looking at it and the wires were coming out the back.

Position three is constant (ground).

Here's the results of my Multi-meter readings.



I'm not sure what that's telling me but at least I have readings.

 

Is there anyway to turn the daytime running lights off while you're driving...? I live in a condo complex and when I turn into my parking space late at night my lights shine right at someone's ground floor bedroom window. I turn off my headlights before I pull in but the daytime running lights seem almost as bright and I'd like to be able to turn them off before I pull in and turn off the car.

 

Man im happy i have Fit and I dont have to worry about DRLs and all this crap about fooling the cars computer with a special harness, Unlike Chevy,Crysler,Dodge,Jeep. HAHA I just plugged mine in and they fired right up with no problems.
And i dont think the new fits have problems with running HIDs either.

 

I have a similar situation. Does anyone have a fix for this?

 

If I remember correctly, US DRLs are supposed to be wired so that they turn off when the headlamp switch is in any position other than off. Try turning just the parking lamps on and see if you're DRLs turn off. If so, does that help your situation?

 

What this tells me is that the high beam filament is being used for the DRLs. It is most likely PWMed to a value above 5.5V (I think that's where the halogen cycle starts to stop and early bulb failure can result). If that's the case, it's confusing to me why you're still reading full voltage at the terminal though. Maybe it has something to do with the PWM duty cycle (i.e. how long its off and on to regulate to the lower voltage). I think you need an ocilloscope to see that data.

The other confusing things I see are:
Why is the low beam filament getting some minimal voltage when the high beams are on? Those should be off.

And why is the DRL (high beam) still reading voltage when the low beams are on? I thought when low beams are turned on, your DRLs turn off?

Are you sure you have your terminals right?

 

Can't you just pull the DRL fuse? That's what I planned on doing when I installed HIDs. I remember reading that somewhere on this forum. I might be wrong.

 

You certainly can. It's Fuse 15 on the 09 Fits.

The problem is, my goal is not to simply disable the DRLs, I wanted to install a retrofit kit and then use the DRL circuit to power my "angel-eyes". That way, I wouldn't have to install a separate switched circuit for them, they would just be "always-on".

Unfortunately, as discussed in this thread, the 09s use the MCU to control the DRLs and therefore the circuit is not accessible like it is on the earlier models.

(at least that's how I've understood it)

It's been a while since I did that set of readings, but I'm positive that's what I was reading. The diagram is drawn as if you're looking at the plug straight on and the wires going to the MICU are coming out the back. What you're looking at in the diagram is what you would then plug right into the back of the headlight assembly.

I can take readings again if you need, but I'm pretty confident I'll get the same numbers as I took the readings about 5 times and when I saw that the numbers were coming out essentially the same, I wrote down the numbers from my last attempt.

 

Doesn't the parking brake act as a "switch" to turn the DRL's on and off? At least that's what I've noticed. As long as the parking brake is enabled the DRL's will remain off, is there some type of switch or sensor on it?

 

I believe only at start of the car. If you park the car and then engage the parking brake, the DRL still stays on.

 

DLR noise (buzz)
back from the dead!!!
i installed the h4 high/low kit off my 07 fit onto my 2010 fit sport w/nav and even after pulling fuse 15 i get a buzzing noise up by the headlight (still need to track down exactly where its coming from) - has anyone run into this? the noise is only if the headlights are off, as soon as i turn them on the noise goes away.
o i did a search and can't find anyone talking about any type of noise. so i figured i'd post here before making a new thread

??????

 

as umop-apisdn pointed out, the DRL system runs on a reduced voltage. Your readings are taken at the headlight harness I assume. And the readings don't make sense because our cars are switch ground, not bulb grounded like most other cars.

This means power travels in the reverse direction for our headlight circuit. It goes from the battery, to an under-the-hood fuse, then feeding the headlights directly. After the bulb, then it goes to the headlight switch (and DRL circuit), where it grounds the circuit depending on the setting you select.

If you want to wire up angel eyes as DRLs, I'd recommend just wiring them to a switched power source and be done with it. If you really want to go all out, you can get a wiring diagram and track down the output wire in the stock DRL system (the wire that's "hot" when the system is on), then use that to trigger the relay and wire it to your angel eyes.

If you just want to be able to manually turn-off the DRL while driving, it should be as simple as adding a switch to the wire behind the fuse (fuse 15 from what I'm reading here) that triggers the DRL system. I'm assuming fuse 15 on the GE is the same as fuse 8 (7.5a) on my Canadian GD (comes with DRL). This wire is simply a switched power trigger for the DRL system and turns on when you turn the ignition on. So by pulling the fuse, you've essentially cut that wire, and now the DRL system doesn't think the ignition is on, thus shutting down the DRLs. So adding a switch inline will essentially do the very same when you turn the switch off.

Sorry, don't check these forums often. Maybe you've figure this out by now. If not, hope this helps.

 

I'm gonna continue this thread with this bit of info from a non-Fit vehicle.

Long story short, I had to replace the H4/9003/HB2 socket on a 1999.5 Nissan Pathfinder.

Afterward, when I put a bulb in... the HIGH beam works fine, but the low beam came out under powered. With a bit of wire swapping (I added a triple barrel connector when I installed the new socket), I got low beam to work at the right brightness.

Somehow, I had swapped the position of two of the wires... both wires for the HIGH beam. My theory is that there are two power lines coming in, one for the low and one for the high, then a shared ground going out.

What do you think would happen if the ground wire was swapped with the power line for the high beam? Well, for high beam it would work, since the filament doesn't care which direction power flows (unlike one-way diodes). But for the low beam, it now has two power lines and no ground. When that happens, one power line BECOMES the ground (if there's a voltage/amp difference, the low one loses).

This was a theory put into practice in computers a while back. You have a 5V line and a 12V line. The fan is too slow with only 5 volts (doesn't push enough air to keep things cool), but too noisy with 12V. If you force the 12V line to ground into the 5v line... you get a fan that runs as if it was a 7V line (faster than 5, slower than 12).

And so, I apply this theory to DRLs... a simple way to get "half" power... make the circuit of the power lines and not the common "ground." Assuming there's a voltage difference... hum.

Assuming nothing fries... VERY cheap and simple way.

EDIT: continuing...

Even if the circuit runs "opposite" as umop-apisdn suggests, you can still complete the "power-to-power" circuit at the switch itself.

BUT, this is just a theory.