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-   -   Driver side headlamp doesn't turn on when running (https://chevroletforum.com/forum/cobalt-32/driver-side-headlamp-doesnt-turn-when-running-89510/)

mbranton March 16th, 2018 8:24 PM
Driver side headlamp doesn't turn on when running
 
I have a 2010 Chevy cobalt. When I unlock it with the keyfob, both headlamps turn on. When I turn the car on, the driver side lamp turns off.
I tested the fuses and there is no issue. I swapped out the lamp and I still haven't fixed the issue.
Does anyone have an idea of what I should be looking for- wiring harness issue?

tech2 March 16th, 2018 10:19 PM
so left daytime running light is out
-everything works with the full light system turned on; highbeam and low beam?

you checked the low beam fuse for each headlamp? cause the dtrl for the left headlamp runs thru both the right and left low beam fuses. the dtrl right side will work even if the right low beam fuse is blown

tim_cleaveley June 10th, 2018 11:59 AM
If all fuses are good and the headlamp works with the key fob it’s probably the DRL - auto headlamp module. Needs to be taken out and replaced or fixed.

tech2 June 10th, 2018 4:39 PM
my diagram shows no dtrl module....the bcm turns on the dtrl relay...one feed from the relay supplies both lights so bcm and relay are working. if the right dtrl is turning on the problem is the wiring to the left light or, right or left low beam fuse.

tim_cleaveley June 11th, 2018 3:56 PM
Your right tech2. My apologizes.

by the looks of it the low beam and high beam relays power both the head lamps simultaneously.

however there is a
Left Hand Low Beam fuse
Left Hand High Beam fuse

Right Hand Low Beam fuse
&
Right Hand High Beam fuse

all 10amp

there is also a high beam resistor.

tim_cleaveley June 11th, 2018 4:00 PM
Just curious, does the Flash to Pass function bring the headlamp on? You can try this by pulling the multi switch head lamp lever forward...

tech2 June 11th, 2018 7:48 PM
Originally Posted by tim_cleaveley (Post 358201)
Your right tech2. My apologizes.

by the looks of it the low beam and high beam relays power both the head lamps simultaneously.

there is also a high beam resistor.


maybe your wiring diagram is different than mine; powerflow for the dtrl (the problem) do not pass thru the low and high beam relays. both relays are turned off when the dtrl are on.
I'm not seeing a resistor for the high beams?
the dtrl are run throught the low beams and most likely pulse width modulated to create a dimmer light output.

tim_cleaveley June 12th, 2018 5:35 AM
I will post a photo of my diagram tonight after work Tech2. I didn’t study it to an extreme, but I do see a high beam resistor.

You are correct in saying that the DRL are powered through the low beam side


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