GMs horrible DRL implementations

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About 3 1/2 months ago my 2003 Buick burnt out its drivers side daytime running light (which is also the turn signal/parking lamp). Fast forward to this month. I've gone through 4 bulbs since the original burnt out. Thinking it was an electrical problem, I started by looking at the bulb socket and all of its connections. I back-probed the connections with the car running (DRLs on), with it off and parking lamps only, with the car running with headlamps on and with the turn signal on. I got readings all over the place. There are 3 pins on the socket harness input and 4 contacts in the socket for the bulb (4157NAK). Depending on which "mode" the lights were in the center pin was sometimes acting as ground and sometimes as the positive (as verified by my multimeter). Voltage was also all over the place. From 12.8-13V and as high as 14.5-15.2V. With the DRLs which only has one filament lit, I was getting a 14+V reading from two of the pins to the ground, so instead of just one circuit there were two operating at the same time. When the turn signal was turned on things got even stranger with both circuits "blinking" (peaks and drops in voltage). In order to make the DRLs function, GM takes the output from the turn signals and light switch (park/low beams) and runs it to the Body Control Module. The BCM in turn passes these feeds along if you signal a turn or if you turn on the parking/driving lamps. If you're not signaling or don't have your headlights on the BCM passes a constant 14.5V or higher voltage to the turn filament to act as the DRLs. The problem with this is the voltage is too high. The bulbs are rated to operate at ~13V, not 14.5 or higher. This causes the contacts on the "hot" terminal in the bulb socket to overheat. It also causes the lead wire on the bulb to overheat and melt the bulbs plastic base. The bulbs still operate fine so long as you make electrical contact after the "burnt" portion of the lead wire but are worthelss in the socket. Eventually the sockets will melt if the problem persists for too long. The solution. Disable the DRLs but cutting the 4 wires in the BCM harness that control the left and right front turn signals. Cut the light blue and light blue/white stripe and splice together. Cut dark blue and dark blue/white stripe and splice together. Ta Da! The BCM is bypassed for turnsignal operations. No more DRLs and no more overheading bulb and socket. If anyone else has this issue here's a link to the directions. http://www.lightsout.org/disable.html
 
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I think my camry had a recall on headlamp wiring burning out like that with the possibility of starting a fire.
 
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You're supposed to use the Long Life bulbs. That's how the original lasted six years.
 

buickman50401

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 Originally Posted By: eljefino
You're supposed to use the Long Life bulbs. That's how the original lasted six years.
I've tried the long life bulbs. They lasted for a whole extra week compared to the standards. Its not a bulb issue its a voltage issue in GMs implementation of DRLs. Regardless of using LL or regular bulbs, the "long life" filament isn't going to correct the problem of the contacts at the base of the bulb burning off like in the photo.
 
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Those voltages are acceptable - car electrical bus voltages vary as needed to recharge battery. What's odd to me is that they'd light both filaments continuously per design. In my experience I've never seen a bulb tolerate that for continuous use-- too much heat for it to dissipate. M
 
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I've gone through alot of turn signal bulbs that burn out every year on my 96 sunfire, they get burned and heavily corroded. i put some grease on the last ones. luckily, my last set from o'reilly is going almost two years now. I haven't had to replace my drl bulbs, my 96 sunfire are originals
 
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Replace the sockets. Burned contacts in the sockets will cause the bulb contacts to burn in short order. 14+ volts is needed to charge the battery, as meep says. 12.0 volts indicates a half-discharged battery.
 
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Bulb rating and actual voltage encountered are normal. You will find just about every auto bulb is rated at the 12/13 volt range. To charge a lead-acid battery you need to apply ~14.7v to it, which is also what is fed around the vehicle to keep things simple. So whos at fault? Vehicle manufactuers for using 14.x volts throughout the vehicle? Or bulb manufacturers trying to eek out longer rated life by refusing to change their rating system? Alex.
 

buickman50401

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 Originally Posted By: GMGuy
Bulb rating and actual voltage encountered are normal. You will find just about every auto bulb is rated at the 12/13 volt range. To charge a lead-acid battery you need to apply ~14.7v to it, which is also what is fed around the vehicle to keep things simple. So whos at fault? Vehicle manufactuers for using 14.x volts throughout the vehicle? Or bulb manufacturers trying to eek out longer rated life by refusing to change their rating system? Alex.
Then what do you make of this? Clearly when the BCM was applying voltage to the DRLs the voltage was much higher then when just the parking lights were on. The car was running during these tests.
 
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You make sure to actually clean the bulbs off with rubbing alcohol? My dad was going thru DRL bulbs on his truck. I asked him if he had been cleaning the bulbs off prior to installation. He thought that was only for headlight bulbs.
 
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Don't many new cars use a transitor to "chop" the voltage to dim the DRL's? I think that makes it hard to get a accurate voltage reading.
 
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Yes, they do, and yes, it makes it hard to get an accurate voltage reading. You can get multimeters capable of measuring pulse width modulation duty cycle which would work....or use an oscilloscope.
 
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Why didn't you just pull the DRL fuse? That's what I did on my Olds mini-van. Quick, simple, and no more DRL.
 
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 Originally Posted By: G-MAN
Why didn't you just pull the DRL fuse? That's what I did on my Olds mini-van. Quick, simple, and no more DRL.
Well, sure, if you want to do it the easy way...
 
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 Quote:
Its not a bulb issue its a voltage issue in GMs implementation of DRLs. Regardless of using LL or regular bulbs, the "long life" filament isn't going to correct the problem of the contacts at the base of the bulb burning off like in the photo.
It is a bulb issue. A bulb issue that GM corrected a long time ago. Find yourself a bulb without the plastic base. Here is a 3157 from Rock Auto, just like the one you had that melted, with only the glass base. You can also pick one up at your local GM dealer. This will solve your problem. http://info.rockauto.com/getimage/getima...ghting/3157.jpg
 
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 Originally Posted By: meep
What's odd to me is that they'd light both filaments continuously per design. In my experience I've never seen a bulb tolerate that for continuous use-- too much heat for it to dissipate. M
You're correct dual filaments are not supposed to have BOTH lighted at the same time as far as I have ever known. Are there any other cars out there that do things this way. Calling auto electrical engineers.....
 
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My VW Eos uses a double filament # 3457 bulb with both lit for the front turn signals. It is not the parking light bulb too.
 
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