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DIY: DRL's & Low Beams (No Switch)

78K views 95 replies 62 participants last post by  Asimo2007 
#1 ·
DISCLAIMER: You perform this mod at your own risk! You assume sole responsibility of execution and outcome of this mod. I will not be held responsible if something goes wrong. AKA If you just so happen to burn your **** to the ground, it’s all on you.

But if you follow these directions, you should do just fine!

This DIY will explain how to hookup your DRL’s to stay on with your low beams WITHOUT running a switch in the cab.


What you’ll need:

1. One 4 prong relay
2. One 1.2 ohm resistor
3. One 30 amp max fuse holder
4. 7.5 amp fuse
5. Length of assorted color 14-16 guage wire
6. Female connectors (blue)
7. T-Tap wire connectors
8. Two “Eye hole” connectors
9. Shrink Wrap


I have read through the first DRL post and noticed that most people like the way this mod looks but they don't want to hassle with running wires for a switch into the cab. They just want the DRL's to be on with the low beams when the headlights are switched on.

The way I have this drawn up allows for the DRL's to be on like normal when the headlights are switched to "off" at the headlight switch and also keep them on along with the lowbeams when the headlight switch is turned to "on".

I'm not sure about changing to different resistors to get different colors from the DRL's or any of that jazz.

I'm using a relay in this setup. A relay is basically an automatic switch. Each 4 prong relay has a 12v constant(30), ground(85), trigger(86) and output(87) prong. What the relay does is connect the 12v constant(30) prong to the output(87) prong when current is introduced to the trigger(86) prong.

So what we are doing here is essence is using a splice from the low beams and using that as a trigger for the DRL's. That way we avoid accidentally leaving the DRL's on when we turn the car off. The trigger from the low beams will then activate the relay and send current to the DRL's.

Sorry for the lengthy explanation, I know pictures will help a lot of you in understanding what I'm talking about. So without further a due…

First is a crappy, yet simple wiring diagram. Kind of gives you an idea of what we’re trying to accomplish when it’s all said and done.




1. We want to start by disconnecting and removing the battery. (Remove negative side first then the positive)






2. Remove the clear reservoir (simply give it a little tug in the upward direction)




3. You will want to tap three wires with your T-Tap connectors.

The T-Tap connectors come in a package that looks something like this:



The T-Tap will look like this:



You will want to tap the driver’s side low beam connector first. It is a purple wire. Fold the T-Tap in half around the purple wire. It should look like this when you are done. (You might need to use pliers to get the T-Tap to click shut)



Then tap the driver’s side DRL (pink wire). It should look like this:



Then tap the passenger side DRL (white wire). It should look like this:




4. You will want to find a 12v constant source. Most people connect straight to the battery. I think that looks like crap. I chose to connect mine to one of the main terminals on the fuse block in the engine compartment.

One of these two big copper tabs should do!



I removed the screw and cut a slot for my wire to come out.



I didn’t take a picture of this next part, but if you want to copy the way I did it exactly, you will want to connect an “eye hole” connector to one end of your fuse holder and then install it on top of the copper tab. Then put the screw back in and tighten it down. For reference, your fuse holder probably looks something like this:




5. Now it’s time to find a mounting spot for the relay. You want it to stay dry and stationary.

There’s a bolt that hold the cross member right under here:



That’s where I chose to mount mine!

Take the bolt out and sand down to the metal (this is where we will connect our ground):






6. Now we can finally run some wire! (This is where the assorted colors of wire come in handy)

Your T-Taps should have come with come covered male connectors. Hook all three of the T-Taps individually to enough wire that all 3 runs will make it to where you will be mounting your relay. The T-Taps should look like this with the male connectors and wire hooked up:




7. Now comes the important part. Wiring the relay. Pay attention. Use the above wiring diagram if you have any questions.

First, make sure you wrap all your male connections in shrink wrap to avoid a short somewhere down the line. They should look like this:

No shrink wrap:



Shrink wrapped:



Shrink wrap comes in a package like this:



You use a lighter to get it to shrink around your connections.

Your relay should look like this:





Now the wire coming from the low beam splice (the purple wire) needs to go to the 86 prong on your relay. The wire coming from your fused 12v constant needs to go to the 30 prong. Both splices from the DRL’s (white and pink wires) need to run to the 87 prong. The 85 prong is the ground, connect a short piece of wire with an “eye hole” connector at the end. The ground wire needs to only be long enough to wrap up to the mounting hole.

It should look like this:




8. I forgot to take a picture of the resistor, but it needs to be run inline to the DRL’s. Without the resistor the high beams will be on with the low beams all the time. I’ll try and snap a quick pic of the resistor to give a visual for this step.



9. Put the battery back in, connect the positive first and then the negative. Everything should clear fine and look like this when you are finished:




I don’t have action shots yet, I had to run a bunch of errands. I tested everything. It all works fine. DRL’s, low and high beams. Let me know what you guys think! Post pics when you’re done!
 
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#26 ·
I'm wondering whether this is a good mod or not.

First, when low beam is on, the current may back flow to the hi beam controller, which may cause a problem. Keep in mind that the DRL / Hi beam circuit is not a simply switch, it consists of a PWM circuit inside the MICU. I'm not saying it must cause a problem, but people try this mod should aware that there is chance you may damage the MICU.

Secondary, using a resistor to drop the volatage is kind of a waste (the voltage dropped become heat), and you will need a pretty high power resistor (see how big it is in the picture). There is a reason why Honda use PWM to dim the hi beam for DRL, but not using a resistor.
 
#90 ·
Annual Bump to an old thread... w/Installation Revisions

Sup dudes and gals. Do people still visit these things? :beer:

So I did a similar mod on my 2010 LX this afternoon, but with a slightly different (and I believe better) approach. I left the DRL circuit alone, and instead modified the headlight circuit to work similar to how aux fog and/or driving (off-road) lights are wired.

The Basics:
The DRLs operate as normal: They are ON when driving with the light switch set to either Off or set to illuminate the parking lights (leave it here to run with both DRL and headlights ON); and OFF with the light switch is set to energize the headlights. The Relay is triggered from the L/side Parking Light, which closes its 30 and 87 contacts, and sends power to the headlights. The Highs operate as normal. The only operational side-effects is that the parking lights cannot be turned on independent of the headlights, and the headlights now flash when the factory alarm is armed/disarmed (this could be resolved by picking up the +12V from a switched, vs. constant source).


What I did:
I cut the factory headlight connectors from the car's wiring, and then spliced them into an unused Hella fog light harness that was laying around. I then insulated the cut factory headlight wires to prevent accidental short-circuiting. I guess removing the headlight fuse would also be wise as it is no longer needed. The harness was then carefully routed and secured with zip-ties to the battery, relay, and both L & R headlights.

Wiring:
- Run relay (+) trigger wire (22 gauge) from L/Parking Light to Relay 86
- Ground Relay Terminal 85 (22 gauge)
- Run 20-Amp Fused +12V to Relay 30 (14 gauge)
- Run Relay 87 output to the headlights (14 gauge from relay, then "T's" using 16 gauge to lights)


Red 22 gauge (+) relay trigger wire to Relay 86


R/side Headlight wires with insulated connectors


Mod'd Hella fog light harness with the spliced-in headlight connector


Headlight ground (14 gauge black) with Relay 85 (22 gauge black w/grey trace) wires @ 6mm bolt (10mm head). 14G green wire from Relay 87 to the headlights.


Standard 30A 12V Relay






Agreed on both points. However a diode would address any feedback issues.

Ugh...thats what i though - you think theres a way you can have it match the output (wattage) as your headlights - i have nokya 2500's and there useless in DRL mode they look there best when there running at around 60 watts (from what ive seen) any ideas anyone?
Then your DRLs will be in High Beam mode! D'oh!

Has anyone done this with no problem? Wats the specs on the resistor(watts and ohms)... I'm a lil sketchy as to the resistor over heating and catching on fire.... Can anybody help?
I second this, anyone in the socal area near anaheim?:wave:
:cheerleader:

So I did this on my 2010 4 dr si and it work exactly how the DIY instructions were! But wondering if anyone can answer this, the 1.2 ohm resistor I got looks exactly the same as the one in the pic but when I turn the lights on it started smokin and gets very hot, I looked it up and said that's it's normal for t to smoke for the first couple mins and that's the resistor does get very hot, just wanna confirm will it catch on fire or blow up or something? And it is normal for it to smoke up for a lil bit? Thanz if you guys can answer this
Anyone having issues with the resistor browning out? It's no big deal but it's just annoying changing it out everytime. I do have lifetime warranty on it, I think I'm on my sixth one.
Rewire to my method.. Or at least ditch that fire-hazard and use this instead: SMAKN® DC/DC Converter 12V (10.5V~40V) Step Down to 7.5V/10A Power Supply Module

Hello


Why do you need to install resistor (in series)? do you need a smaller voltage on your lights?
Resistor drops the voltage, same what Honda does to run dim DRLs.
 
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