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2011 CTS performance mdl 3.6L FE5
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Discussion Starter #1
Hello all

has anybody measured the voltage on the DRLs? I’ve tried using hid bulbs but they are very hit or miss. Since this drls run at a low light level I was wondering if those bulb sockets only receive 6 volts or something like that. If so that would explain my issues.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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DRL, in some models, is the high beams set to series operation by a relay, which runs the bulbs at 6 to 9 volts for reduced intensity and longer life. Since the Daytime Running Lights are for alerting purposes only there's no sense in burning them at full power.

There's a reason that HIDs are normally used for low beams only - power requirements and slow warmup times - unlike halogens which can change brightness instantly.
 

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'12 CTS Performance Sports Wagon AWD
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HID's can NOT be used as DRL lights. You will burn them out quickly. You can do a search on them to find out the reason why but the ballasts won't work correctly etc. I believe the DRL is 9 volt.

Your only option is DRL friendly LED's or Halogen. The DRL friendly LED's will run without problem at the lower voltage. If they do not list as being DRL friendly they may also fail quickly.

But be aware that LED's in the Cadillac housings will be hit and miss. You may find one that works really well, or they may have the focal point in the wrong position and really suck for light output. Really, for the Halogen housings you need to stick with Halogen for the low beam. LED MAYBE for the highbeam if you can get the focal point correct but I would definitely not use HID's either for high beams as they can not handle being turned off and on consistently like a normal highbeam would.

Rodney
 

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2010 CTS4 sedan
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FWIW, I put 8w H16/5202 JDM Astar brand LEDs in my DRLs over four years ago and they have worked perfectly all this time. At the same time, I upgrade the foglights to something with a bit more wattage and they're still going strong - that being said, I rarely use them.
 

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**2014 CTS4 Sport Wagon-Luxury**
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and remember there are at least two different headlight/housings for our cars...us lesser CTS owners have halogen (regular headlight at a slightly lower power for the DRLs) as OEM while you higher ups have the non halogen type...

I can't imagine that the halogen headlight housing would work with a HID bulb set up...but maybe my imagination or lack thereof is holding me back ;)

Bill
 

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2011 CTS Coupe Premium
Orlando - We take orphans
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Ran a test some time ago and found that the best halogens (e.g. SilverStar Ultra) were brighter than 55w HIDs. LEDs may be better but don't trust the little fans in the base.
 

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2011 CTS performance mdl 3.6L FE5
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Discussion Starter #7
Thank you all for the response on this thread,

I was really silly making the assumption that GM would use DRL bulbs that were made for 12Volts to keep things simple rather than lowering the voltage across the bulbs themselves to 9V, so that's what I get for assuming and not measuring 🤦🏻‍♂️.

since the DRL circuit is running at 9V it will never run properly with HId ballasts. I’m Kinda surprised they ran as well as they did. By the way I used a set of HIDs that were 25 Watts and they run fantastic for the fog lights but NOT the DRLs. That should have been my first clue.

So what I did for the meantime is just put the old incandescent lights back in (UGHHH) until I get the time to get some LEDs that won't burn up in that light housing. I used LED’s before and they failed fairly rapidly, that's why I tried the HID’s.

At any rate, there are some great suggestions in this thread I will be using later on when I get the time.

Thanks all!
 

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'12 CTS Performance Sports Wagon AWD
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As I said, you need to find LED's compatible with the lower voltage of the DRL. They are out there. The newer ones also don't have fans on them necessarily. I accidentally pulled one of the wires out of one of mine that had the seperate electronics and those style are discontinued now. I got one that is all in one bulb but I did get one with a fan on it. There were many others without them. This light is as bright or brighter than the OPT7 it replaced. I kept the other new bulb so I am running some off brand LED in one side and the opt7 in the other side. Hard to tell the difference in the light output.
 
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