How to make DRLs stay on all the time?

[LTG515]

Hey there. I’ve got an 04 Tahoe that I just replaced my DRLs on. Changed them to an amber colored LED and I really like the look. They look great during the day but even better at night, so I was wondering if there’s a way to have the DRLs running at all times. Both during the day as normal, and also still running when the headlights come on.

Anyone know how to make that happen or have ideas?

Thanks!


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[DougAMiller]

Hey there. I’ve got an 04 Tahoe that I just replaced my DRLs on. Changed them to an amber colored LED and I really like the look. They look great during the day but even better at night, so I was wondering if there’s a way to have the DRLs running at all times. Both during the day as normal, and also still running when the headlights come on.

Anyone know how to make that happen or have ideas?

Thanks!


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This has been discussed at length on this forum, usually because people want all four headlights on with high beams (4 hi mod) or with low beams and fog light on with high beams (6 hi mod). you can search for those terms to see the different methods people have used. Most put diodes in the underhood fuse box to cause the high beam relay activation terminal to also activate the other lights that they want to be on with high beams. There is also a commercial solution called Fleece, which is a plate that you put in your fuse box and then plug the relays in on top of it. Here is one place that you can get it: https://www.thoroughbreddiesel.com/gm-alo-37/

My preferred method was to do it at the BCM. I wanted the DRLs to stay on with the headlights, and for the low beams and fogs to be on with the high beams. I guess you could call this the 8 hi mod. So I built a small module about the size of a quarter that has four diodes in it with four wires coming out and connected it to the light relay control pins on the C2 connector of the BCM. This way the fuse box isn't cluttered up with the diodes. These are the connector positions for the light relays on the BCM. I didn't use the park lamp control, as that wasn't needed for my set up, I only highlight it to show all of the lighting control relays.

By putting a diode between the two relay controls that you want to work together, you can get the effect that you want. If you want those two lights to always be on together you can just use a wire jumper and not use a diode. The diode lets one of the lights be on by itself, but turns them both on if the first one is on. Most diodes have a silver ring painted around one end like this.

The ring end connects to the light that you want to use to turn on the other light, and the other lead is connected to the light that you want to turn on. The diode only allows electricity to flow one way, so the light connected to the silver end won't be turned on by the light connected to the other end. If you're not getting the result that you want, you probably have the diode connected backwards.

Hope this all made sense and as I said this is discussed elsewhere in this forum too.

 

[LTG515]

Hey Doug, thanks a bunch for the thorough reply! Yea, I looked around quite a bit but mainly noticed people wanting to turn off their DRLs and such. I’m not very electrically savvy so I’m sure I missed a lot haha.

I’ll think about if this is something I can handle doing on my own and also take a look at that commercially bought options as well.

Thanks!


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[DougAMiller]

Hey Doug, thanks a bunch for the thorough reply! Yea, I looked around quite a bit but mainly noticed people wanting to turn off their DRLs and such. I’m not very electrically savvy so I’m sure I missed a lot haha.

I’ll think about if this is something I can handle doing on my own and also take a look at that commercially bought options as well.

Thanks!


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Well, I probably made my reply a lot more complicated than it needed to be. Your request was just to have the DRLs stay on when the headlights are on. To do that you need to connect a diode between the DRL control pin and the Low Beam control pin, with the silver ring connected to the Low Beam. If you don't use a diode, your headlights will be on during the daytime when your DRLs are. You can connect the diode between pins A4 and B4 on the gray connector of the BCM (its underneath the steering wheel column, behind the lower dash panel), or you can do it at the fuse box. To do it at the fuse box, find the HDLP-LOW and DRL relays and connect your diode between pin 85 of the two relays (its marked on the relay).

 

[LTG515]

Well, I probably made my reply a lot more complicated than it needed to be. Your request was just to have the DRLs stay on when the headlights are on. To do that you need to connect a diode between the DRL control pin and the Low Beam control pin, with the silver ring connected to the Low Beam. If you don't use a diode, your headlights will be on during the daytime when your DRLs are. You can connect the diode between pins A4 and B4 on the gray connector of the BCM (its underneath the steering wheel column, behind the lower dash panel), or you can do it at the fuse box. Find the HDLP-LOW and DRL relays and connect your diode between pin 85 of the two relays (its marked on the relay).

Ok great!! This will be super helpful when I get around to tackling it. Thanks for the helpful replies!


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[LTG515]

Hey Doug,

I ended up getting to the DRL mod and, as far as I can tell, came out real nice! While I was at it, I also made it so that the low beams stay on when the high beams come on. Thanks a bunch for your help!

I’m not VIP so can’t do more than one pic per post.

Don’t mind the half finished front bumper. That’s still a work in progress haha.

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[LTG515]

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[LTG515]

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[LTG515]

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[DougAMiller]

Happy to help! Never understood why GM thought that turning the low beams off when the high beams are on was a good idea.

 

[muncie21]

The headlight sockets in my 2009 and 2014 Yukon both showed signs of over heating when I changed the bulbs. I'm no electrical engineer, but I would think that having more lights running on the same circuit at the same time, than the circuit was designed for (think low beams, high beams and fogs as a 'worse case') may result in more current flow and thus more heat.

Here's what my headlight socket looked like when I replaced the headlight in my 2016 recently.

 

[LTG515]

The headlight sockets in my 2009 and 2014 Yukon both showed signs of over heating when I changed the bulbs. I'm no electrical engineer, but I would think that having more lights running on the same circuit at the same time, than the circuit was designed for (think low beams, high beams and fogs as a 'worse case') may result in more current flow and thus more heat.

Here's what my headlight socket looked like when I replaced the headlight in my 2016 recently.

View attachment 238977

Yea I thought about that as well.


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[malmed]

I did the 4 high mod using diodes, and changed my DRL to amber, and my high beams to halogen...

 

[bobbybananahead]

Well, I probably made my reply a lot more complicated than it needed to be. Your request was just to have the DRLs stay on when the headlights are on. To do that you need to connect a diode between the DRL control pin and the Low Beam control pin, with the silver ring connected to the Low Beam. If you don't use a diode, your headlights will be on during the daytime when your DRLs are. You can connect the diode between pins A4 and B4 on the gray connector of the BCM (its underneath the steering wheel column, behind the lower dash panel), or you can do it at the fuse box. To do it at the fuse box, find the HDLP-LOW and DRL relays and connect your diode between pin 85 of the two relays (its marked on the relay).

Searched internet for weeks, got these headlights new for $100 on ebay. Threw led bulbs in, wanted the led drl bars to work with headlamps low beam, and you literally saved me. I can return my waterproof connectors, add a circuit fuses, switches, extra wires and looms. The diode i didnt have, took apart a viper alarm and remote start system, from my old 06 milan, it was shorted anyway. Took the one diode out of the 20 inside it, desoldered it, soldered wire leads to each end. Followed instructions to pins 85:85 on both relays. Silver end to the headlight side. Black side to drl. You sir are the best. Im so happy. My woman thinks i had the brains to do it myself. Our secret. Thank you! It looks so bad ass now. You seriously rock! May the universe send you money 10 X over. I owe you beer money.

 

[DougAMiller]

Glad you found this to be helpful. Looks great!