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Driving Sunday afternoon, I had an occasion to use the Flash-to-Pass feature and found it did not work. I also could not turn on the high beams which led me to the owner's manual. It turns out that the high beams cannot be activated if the HID lamps are not on (high or low beam). When the headlight control is in the Auto position during the day, the DRLs are on and the HIDs are not, so the high beams cannot be activated (which includes Flash-to-Pass).

To get around this problem, it is necessary to move the headlight control from Auto to the headlight position, which turns on the HID low beams. Now the HID lamps can be switched from low to high beam or vice-versa.

Bottom line, any time the HID lamps are not on, requests to switch to high beams will not work. Maybe this will save some people some worry and some research.:annoyed:
 

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04 CTS-V, 05 STS, 07 SRX- All sold :(
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Most GM vehicles with HIDs lack the "flash to pass" feature during daylight. The reason they give is that the quick off/on/off is bad for the xenon bulbs. Some people dispute the truth of this, but considering that GM vehicles have had the feature for years, I don't see why they'd have omitted it unless it was true.
 

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Thanks for the info. 95% of the time during the day I run with the DLRs and HID off and I always wondered why the flash to pass never worked.
 

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CTS-V 2009 White Diamond, 996TT Silver, G35 Coupe 6mt, M45S
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Very odd behavior for a car. The hig hbeam flash is a requirement for all cars. I can't believe it doesn't work (I checked:it doesn't!)....
How am i going to signal the on coming traffic to watch out for the waiting cop??????
 

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Discussion Starter #5
jwa999, I told you how to get around the problem. Switch from Auto to headlight and the high beam will activate.
 

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2017 ATS-V Sedan, Vector Blue/Black, 6MT
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Flash to pass is NOT a requirement for cars in this country. The base CTS DOES have flash to pass, but never with the HIDs. This is noted in the owner's manual, and Consumer's Reports even mentioned it in their review of the CTS. If they can't do daytime brights with the HID, I would appreciate some other solution, like auxiliary superbright LEDs, or even an incandescent bulb of some sort.
 

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Driving Sunday afternoon, I had an occasion to use the Flash-to-Pass feature and found it did not work. I also could not turn on the high beams which led me to the owner's manual. It turns out that the high beams cannot be activated if the HID lamps are not on (high or low beam). When the headlight control is in the Auto position during the day, the DRLs are on and the HIDs are not, so the high beams cannot be activated (which includes Flash-to-Pass).
Explanation: HIDs take a small amount of time to power up. Much slower than traditional halogens. You'll note this when you first start your car in a dark garage. The intensity of the light from the HIDs takes a second or two to come up to full strength.

Because of this, it's actually not legal to have separate HID high beams in the US. We have an obscure requirement that high beams come on within a certain amount of time, and most HIDs fail that test.

What IS legal (and something Porsche has been doing for a while) is a bi-Xenon light. Basically, the headlight has a pivoting reflector in it that moves when you flick the high beams on. It changes the shape and direction of the light output. And that pivoting mechanism can be actuated almost immediately.

To experience this, go open the door of your car (or the driver's window), and stand outside the car. Turn the lights on. Flick the high beams on. Hear the "CLICK"? Flick them off. "CLICK." That's the reflector moving.

So, put 2 and 2 together. The V has HID high beams, and because of that obscure requirement, they're the same HID bulb as the low beams. The only way to make that work right is a moving reflector. Flash-to-pass in most cars activates the highs repeatedly. In order to do that with the V, the lows have to already be powered up.

Clear as mud? :)

jas
 

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Discussion Starter #8
I have come to the conclusion that most people don't read all of these posts. If they did, they would not be asking how to get get around the problem. marktanner, please read my response to jaw99.
 

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Discussion Starter #9
Now, jvp provides an accurate explanation of how the 2009 CTS-V headlights work (I might mention that the DTSs with HID headlights work the same way). He, however, blames this operation on some "obscure requirement." In fact, it saves money to have only one HID bulb with a shutter to switch from low to high beams. Saving money is always the explanation for most things. On the 2004-2007 CTS-V, the low beams were HID and the high beams were incandescent (maybe because of the "obscure requirement"). As soon as it became less expensive to provide a shutter rather than a separate bulb, a single HID bulb is used for both.
 

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CTS-V 2009 White Diamond, 996TT Silver, G35 Coupe 6mt, M45S
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Thanks very much of the info you'all. Without this post i'd never have known that my brights didn't work and why! (my response to the thread was just a little sarcasm :)

What I would GM expect to do is *emulate* the behaviour of flashing your brights... I pull the handle, car powers up those HIDs and flash! Now I have to do that manually!
If I ever get a hold of the firmware of this car.....

This is my first GM car... Also, everybody notice that if you lightly touch the blinkers they blink 3 times for a lane change.. Discovered this by accident. Manual describes it. Very handy!

Hans.
 

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2017 ATS-V Sedan, Vector Blue/Black, 6MT
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TedCMiller, I've always known that you can turn the lights on to get the brights to flash. Brights are also used as a visual horn, and for this usage one might not have the time or ability to turn the lights on first. That's why I suggested that Cadillac consider a dedicated bulb or LED for this purpose. Heck, the DRL's might even be able to be modified for this purpose. At night,the system could revert to using the high-beams, as it already does. I think some sort of easily and instantly accessible "visual horn" is a great safety feature, and one that I miss on my car.
 

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Discussion Starter #12
To whom it might concern:
What I did not know was that the high beams do not work if the headlights (usually low beams) in an HID system are not on. In the 2004-2007 CTS-V (I had a 2004 and a 2005 CTS-V) there was a non-HID high beam so that Flash-to-Pass worked as expected day or night. When the Flash-to-Pass feature did not work in the day time on my 2009 CTS-V, as it had on the two CTS-Vs that I had owned earlier, I became concerned enough to read the owner's manual. This thread was directed at ignorant people like me who did not know that the Flash-to-Pass feature worked only if the HIDs were already on. It was not intended for those who already had the infromation offered here. Sorry if I wasted anyone's time.
 

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This is the weirdest thread ever. :suspect:
 

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I had my Aston Martin Vantage special ordered from Aston Werks to include daytime running lights (not standard or an option) and the same thing I discovered - quite an odd thing!

Rick H
 

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I was not aware of this until I read this thread and tried it out in my car. I like being able to flash the high beams, if for no other reason than to warn cars that appear like they're about to pull out in front of me from a side street. I hate that!!

Tony
 

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What about just leaving the lights in the ON position all the time? I remember on my C6 Corvette, I was able to leave the headlight switch to the on position at all times and when I would shut off the car, the lights would turn off too. Same thing with my Escalade, I think. Does the CTS-V work the same way where you can leave the lights on and when you turn off the car, the headlights shut off too?
 
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