[mdgreenster]

Last night I found that my headlights won't come on in either automatic or manual control. I do get an indication that the lights should be on. In daylight I find that the DRL's don't work either. I've checked all the fuses that are associated with such, all ok. Any thoughts?

 

[Barry]

Any chance you have a wiring harness connector that is disconnected or loose? Has there been any recent maintenance or modification done to the car?

How sure are you about the fuses? There are numerous fuse panels and there may be multiple fuses that could affect this. Also, a fuse could be bad without looking like it is blown. It may be worth replacing the relevant fuses anyway or using a continuity tester on them as a simple/easy possible fix before pursuing harder fixes.

I am not sure what ground connections are relevant to the lights, but bad ground connections in general are very common electrical problems in cars. I would look into that next.

 

[mdgreenster]

I'm guessing it's a connector somewhere as well. The only connectors I can easily see are the ones at the headlights. I checked the fuses with a meter that had any mention of lights in the right/left/engine fuse blocks. I've got an appointment for service on Friday. I'll report back what they find. Thanks.

 

[jcanoe]

What about the high beam headlights? Do the high beams come on or can you flash the high beams?

 

[oldstuff]

What about the high beam headlights? Do the high beams come on or can you flash the high beams?

The high and the low are the same bulb--just a lift gate to change the beam pattern.

 

[jcanoe]

Thanks. In the Gen 2 the low beam headlights are LEDs and the high beams are halogen bulbs.

 

[mdgreenster]

Well it turns out that both headlight bulbs burned out at roughly the same time. I took out the left headlight bulb(easy to get to) and ohm'd it out and it read open. I checked the voltage at the plug and got 14V. I was shocked at the cost of new bulbs ($35/ea). That's much better than a trip to Chevy Service Dept. and a $175 diagnostic plus parts. I'm glad I considered the possibility of both bulbs being bad.

 

[Barry]

That doesn't explain why the DLRs don't work. But be aware that the DLRs turn off when you shift to Park, so it is not dead simple to check them alone.

 

[mdgreenster]

That doesn't explain why the DLRs don't work. But be aware that the DLRs turn off when you shift to Park, so it is not dead simple to check them alone.

DRL's were okay. I didn't realize they are off while in park. My wife drives the Volt so maybe she didn't notice a headlight out until the other one burned out as well.

 

[hellsop]

DRL's were okay. I didn't realize they are off while in park. My wife drives the Volt so maybe she didn't notice a headlight out until the other one burned out as well.

Plus, they're kind of SUPPOSED to burn out at the same time, absent a defect in only one of them. They're the same age, of the same design, probably made on the same production line at about the same time, were shipped by the same means to the same place, then installed at the same time, run for exactly the same number of hours in exactly the same conditions... It's only sloppiness that would make them fail at DIFFERENT times.

 

[oldstuff]

Plus, they're kind of SUPPOSED to burn out at the same time, absent a defect in only one of them. They're the same age, of the same design, probably made on the same production line at about the same time, were shipped by the same means to the same place, then installed at the same time, run for exactly the same number of hours in exactly the same conditions... It's only sloppiness that would make them fail at DIFFERENT times.

That's like saying all four tires should blow out at once if one of them fails.
Deeply flawed supposition. Sounds good though.

 

[jcanoe]

Plus, they're kind of SUPPOSED to burn out at the same time, absent a defect in only one of them. They're the same age, of the same design, probably made on the same production line at about the same time, were shipped by the same means to the same place, then installed at the same time, run for exactly the same number of hours in exactly the same conditions... It's only sloppiness that would make them fail at DIFFERENT times.

I always thought that the reason the second headlamp bulbs burns out soon after the first is a broken heart. Maybe when the first bulb fails there is a slight increase in voltage in the system, this stresses the already aged filament in the second bulb and it soon fails too.

 

[Steverino]

Reliability will have a variance tolerance. One bulb may (and likely will) fail before the other. The time between the two failing should fall within the variance tolerance. If both failed same day during daylight, they could have been 8 hours apart and you could easily have missed it.

 

[Sly Bob]

It's always been pretty typical that when one headlight bolt blows the other goes shortly thereafter.