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Discussion Starter · #1 ·
Hi folks, has anyone run into this before? My driver's low beam will not come on, but the rest of the lights work. I get a low beam headlamp fault on the console, but when I replaced the bulb, it still doesn't work. The car is 6 months old and there's no condensation inside the housing. The fuses check out. The wiring harness looks OK, but I don't know which pin is supposed to drive the low beam.

Any ideas? I'm still well under warranty so I guess I'm heading to the dealer, I just don't want to miss something simple.

Thanks for the help!
 

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Try to disconnect the battery then reconnect it. See if that will do a "reset" of sorts on the electronic system. Before you go hunting around for other issues.
 
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Is it a 2016 only 6 months old? If so take it to the dealer for warranty.
 

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The lighting on the ST, regardless of trim level is controlled by the BCM (body control module). The BCM uses what is referred to as FET (field affect transistor) to prevent damage to the module while controlling a 12 volt function. If the BCM determines that there is a change in voltage, it will shut down the FET and the light will not longer work. When this occurs, the BCM will network a message to the IC (instrument cluster) for a driver visible warning. At the same time, it will set a DTC for the corresponding light and which fault it detected, open, short, high voltage, low voltage, etc.

Long story short, you can replace a faulty light component 100 times but if you don't clear the code, the BCM will never know to resume normal operation.

This should of been taken to the dealer. No offense. These arn't your ma and pa kinda cars anymore, they are complicated.
 

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The lighting on the ST, regardless of trim level is controlled by the BCM (body control module). The BCM uses what is referred to as FET (field affect transistor) to prevent damage to the module while controlling a 12 volt function. If the BCM determines that there is a change in voltage, it will shut down the FET and the light will not longer work. When this occurs, the BCM will network a message to the IC (instrument cluster) for a driver visible warning. At the same time, it will set a DTC for the corresponding light and which fault it detected, open, short, high voltage, low voltage, etc.

Long story short, you can replace a faulty light component 100 times but if you don't clear the code, the BCM will never know to resume normal operation.

This should of been taken to the dealer. No offense. These arn't your ma and pa kinda cars anymore, they are complicated.
In my experience, just replacing the light (halogen) and it works fine on next start up. I've never had to clear a code when replacing the lights or turning the lights on with the housing out of the car (not plugged in).
 

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Discussion Starter · #7 ·
The lighting on the ST, regardless of trim level is controlled by the BCM (body control module). The BCM uses what is referred to as FET (field affect transistor) to prevent damage to the module while controlling a 12 volt function. If the BCM determines that there is a change in voltage, it will shut down the FET and the light will not longer work. When this occurs, the BCM will network a message to the IC (instrument cluster) for a driver visible warning. At the same time, it will set a DTC for the corresponding light and which fault it detected, open, short, high voltage, low voltage, etc.

Long story short, you can replace a faulty light component 100 times but if you don't clear the code, the BCM will never know to resume normal operation.

This should of been taken to the dealer. No offense. These arn't your ma and pa kinda cars anymore, they are complicated.
Oh, it's going to the dealer. The LED doesn't work anymore, either :(

The turn signal is working fine, but since it's an ST1 those halogens aren't bright enough for me to drive around with just one working. Plus, with only one working eyebrow the car looks stupid. I'll post again after Wednesday with whatever the problem was. It's probably a good idea to make a note of it.
 

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Oh, it's going to the dealer. The LED doesn't work anymore, either :(

The turn signal is working fine, but since it's an ST1 those halogens aren't bright enough for me to drive around with just one working. Plus, with only one working eyebrow the car looks stupid. I'll post again after Wednesday with whatever the problem was. It's probably a good idea to make a note of it.
Pop out the housing, unplug it, and replug it in.
 

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Discussion Starter · #9 ·
Pop out the housing, unplug it, and replug it in.
Hand to God, I did that twice and it still wouldn't come back on. I took it to the dealer and they claimed the plug fell off, which I doubt unless it happened in the 7 miles between my house and the dealer. However, that was last week and it hasn't given me any trouble since. It's still the original bulb, and the LED is back on. Like tpiechow said, maybe there's a code that has to be cleared/checked before it will work again.

This may or may not be a problem long term. I had an Escort in the 1980s that would burn out the right rear tailight on a near monthly basis. It happened so often my brother and I kept a six pack of bulbs in the hatch and left the trim off the inside so we could replace it at will. If the halogen lasts at least a year, then I'm good. If I have to take it to the dealer monthly, I might start complaining.
 

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Discussion Starter · #10 ·
Hand to God, I did that twice and it still wouldn't come back on. I took it to the dealer and they claimed the plug fell off, which I doubt unless it happened in the 7 miles between my house and the dealer. However, that was last week and it hasn't given me any trouble since. It's still the original bulb, and the LED is back on. Like tpiechow said, maybe there's a code that has to be cleared/checked before it will work again.

This may or may not be a problem long term. I had an Escort in the 1980s that would burn out the right rear tailight on a near monthly basis. It happened so often my brother and I kept a six pack of bulbs in the hatch and left the trim off the inside so we could replace it at will. If the halogen lasts at least a year, then I'm good. If I have to take it to the dealer monthly, I might start complaining.
Well, it's been a year! No problems. Maybe it was just a crappy assembly at the plant.
 
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