Question about RS DRLs--PWM driven by BCM?? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Hephaestus1 · 06-26-2010, 04:32 AM

I finally got the Helm service manuals, as I have been salivating about how to "fix" the DRL operation (to my tastes). Since I got the AAC P13 LED bulbs, I see the DRLs as DRL/Fogs, so I plan to install a forced, manual switch which allows me to decide when/if they are on (I do NOT want the side-marker harness solution).

In reading about the RS DRLs, I came across some very disturbing verbiage and schematics which show the BCM providing unfused, Pulse-Width Modulated "power" to the DRLs. Is this correct? Why would any engineer in his right mind ever power a DC light bulb with half-baked AC? Surely there has to be another component in the path between the BCM and the DRLs that I'm missing...

Thanks,
Brian K.

slick rick · 06-26-2010, 06:43 AM

Yup, PWM

http://www.camaro5.com/forums/showpo...9&postcount=41
http://www.camaro5.com/forums/showpo...1&postcount=50

Hephaestus1 · 06-27-2010, 12:20 AM

Okay, thanks Slick. At least I've not completely lost my mind. That fracks up my original "easy" plan, have to do some more noodling.

Sounds like they're sacrificing bulb life for a simpler way to run the bulbs in a "reduced-power" mode.

Mag-Tex · 06-28-2010, 12:37 PM

The DRL bulbs may, in fact, be PWM. But I can verify that if you put 12v DC direct to them, there is absolutely no difference in look or brightness. I have mine on at night via fuse block feed and cabin switch (with diode to prevent backfeeding BCM). In the daytime there is no difference if I turn the switch off. Been this way almost a year with no problem, too.

fieldgoal00 · 06-28-2010, 03:50 PM

There is another solution other than the sidemarker harness that will allow you to do what you want.

Hephaestus1 · 06-28-2010, 11:48 PM

Good info there, Mag. Hmmm, no difference between DC and PWM? Sounds like the BCM is running at least 88% duty cycle. Did you grab your fuse from the IP block, or under hood?

Fieldgoal, I like making the "art" mine, to a degree. And I'm not bad with a soldering iron

(Next "planned" project is a T-bar gear selector with ray-skin wrap)

HaZe_X · 06-29-2010, 12:07 AM

Quote:

Originally Posted by Hephaestus1

Good info there, Mag. Hmmm, no difference between DC and PWM? Sounds like the BCM is running at least 88% duty cycle. Did you grab your fuse from the IP block, or under hood?

Fieldgoal, I like making the "art" mine, to a degree. And I'm not bad with a soldering iron

(Next "planned" project is a T-bar gear selector with ray-skin wrap)

If the DRL's are anything like GM's other DRL's, i would think its closer to 70% based on past experimenting. Im talking to the bulb though, not BCM. I could be wrong though with the camaro though, thats just how it was for me in past GM DRL cars.

06-26-2010, 04:32 AM	#1
Hephaestus1 Drives: 2010 2LT/RS A6 Join Date: Dec 2009 Location: Between a Rock and a Weird place, TX Posts: 37	Question about RS DRLs--PWM driven by BCM?? I finally got the Helm service manuals, as I have been salivating about how to "fix" the DRL operation (to my tastes). Since I got the AAC P13 LED bulbs, I see the DRLs as DRL/Fogs, so I plan to install a forced, manual switch which allows me to decide when/if they are on (I do NOT want the side-marker harness solution). In reading about the RS DRLs, I came across some very disturbing verbiage and schematics which show the BCM providing unfused, Pulse-Width Modulated "power" to the DRLs. Is this correct? Why would any engineer in his right mind ever power a DC light bulb with half-baked AC? Surely there has to be another component in the path between the BCM and the DRLs that I'm missing... Thanks, Brian K.

06-26-2010, 06:43 AM	#2
slick rick SoCal Mayhem Drives: 2010 Camaro 1SS/RS Join Date: Aug 2008 Location: Foothill Ranch, CA Posts: 5,488 View My Garage	Yup, PWM http://www.camaro5.com/forums/showpo...9&postcount=41 http://www.camaro5.com/forums/showpo...1&postcount=50 __________________

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06-27-2010, 12:20 AM	#3
Hephaestus1 Drives: 2010 2LT/RS A6 Join Date: Dec 2009 Location: Between a Rock and a Weird place, TX Posts: 37	Okay, thanks Slick. At least I've not completely lost my mind. That fracks up my original "easy" plan, have to do some more noodling. Sounds like they're sacrificing bulb life for a simpler way to run the bulbs in a "reduced-power" mode.

06-28-2010, 12:37 PM	#4
Mag-Tex Drives: 2010 Camaro 2LT/RS Join Date: Aug 2009 Location: Texas Posts: 55	The DRL bulbs may, in fact, be PWM. But I can verify that if you put 12v DC direct to them, there is absolutely no difference in look or brightness. I have mine on at night via fuse block feed and cabin switch (with diode to prevent backfeeding BCM). In the daytime there is no difference if I turn the switch off. Been this way almost a year with no problem, too.

06-28-2010, 03:50 PM	#5
fieldgoal00 Account Suspended Drives: 2010 Chevy Camaro 2SS/RS Join Date: Dec 2008 Location: New Orleans Posts: 769	There is another solution other than the sidemarker harness that will allow you to do what you want.

06-28-2010, 11:48 PM	#6
Hephaestus1 Drives: 2010 2LT/RS A6 Join Date: Dec 2009 Location: Between a Rock and a Weird place, TX Posts: 37	Good info there, Mag. Hmmm, no difference between DC and PWM? Sounds like the BCM is running at least 88% duty cycle. Did you grab your fuse from the IP block, or under hood? Fieldgoal, I like making the "art" mine, to a degree. And I'm not bad with a soldering iron (Next "planned" project is a T-bar gear selector with ray-skin wrap)