In this video, we're gonna go over how you can check and diagnose your daytime running
lights, also known as DRLs, this happens to be a GM vehicle, but other vehicles may be
very similar.
You may not even know that you have a daytime running light out unless someone told you,
even then they're not always that easy to check.
If you're checking the headlights, you can just turn the switch on, if you'rr checking
the fog lights, push the switch, if you're checking the brake lights, push the switch
and you're just gonna have to run real fast.
But there's no switch to turn on those DRLs.
And if it's not a sunny day out, here's what you do, right here on the dash is where the
ambient light sensor is, and that's what's gonna read the light and see whether the daytime
running lights need to come on or whether it's too dark and the regular headlights need
to come on.
Now you could have these somewhere in the middle of the dash, or somewhere to the side,
it probably looks like a little half dome like this.
And if you cover it up, if you're one of those people that put stuff on their dash like a
notebook, then your daytime running lights aren't gonna work at all, and it's gonna be
just headlights all the time, you're gonna burn out your headlight bulbs a lot quicker.
So the first thing you wanna make sure is don't have anything on your dash.
The way to check them is take an extremely bright light.
And we're actually gonna put it right on the sensor.
You know, if you were outside in the sun, you probably don't have to do this stuff.
But even if you're in a building where there's extremely bright lights like in here, they
don't always work, you're gonna need to use a flashlight.
Normally when I turn the key on without that light there, the headlights come on.
Now I have the key on and none of the lights are on.
So I know that sensor is at least working, the computer knows enough not to turn the
headlights on but it didn't turn the daytime running lights on yet.
To turn these on, you actually have to put the vehicle in reverse, drive, or neutral.
Now, that's not the easiest thing to just put it in gear and then run around and check
those.
It's always good to have someone else outside the vehicle checking those while you do that,
you don't necessarily wanna get out of the vehicle.
The vehicle doesn't have to be running in this instance, some vehicles they do, in some
vehicles, if you put the parking brake on the daytime running lights don't work.
Now we have them on now we can check and see if one of them is burnt out.
And it's always a great idea to chuck the wheels just in case you don't want the vehicle
rolling around.
Well, the better thing to do is have someone sitting in the vehicle with their foot on
the brake.
So this is an extremely common occurrence where you see a GM vehicle with the daytime
running light on and the other side is burnt out.
So let's take a look at it.
So if you pull the socket out of the light assembly, you can take a look at it.
And you can sometimes see if the bulb looks like it's a little dark.
Or see if the filament is burnt out.
And it doesn't look too bad, it looks a little bit dark.
And pull the bulb out.
And if you look inside here, it gets very hot.
If you think about it, this thing's on all day long while you're driving.
So sometimes these can melt, the contacts might not be good in there, we take a good
look, this one doesn't look too bad.
But I've seen a lot worse and you see a lot of these melted.
In that case, you're gonna have to replace this also when you pull the bulb out you could
see on the bulb sometimes this part will be burnt out where the contact is on the bulb
itself.
It's a 3156 bulb, single filament bulb, in the event that you have a bad socket, you're
gonna wanna replace it with the new socket, you shouldn't have some wires coming off and
you're gonna cut and splice the wires and attach them accordingly.
You should have some connectors.
Sometimes they're shrink wrapped connectors, so they keep the elements out and those will
help a lot, make sure you tape up some of this wiring harness, that'll be good.
It's okay if the wiring harness comes out a little bit longer, you have a lot of room
to put some extra wire.
And putting the bulb in and put it back together.
In the event that you only have one daytime running light working, most likely it's either
a burnt out bulb or the socket is burnt out and you need to replace it.
In the event that neither bulb is working, the first thing you wanna check is the fuse.
There's a daytime running light fuse itself just pull the fuse box cover off and check
that fuse.
In the event that the fuse is blown, most likely there's another condition whether it's
the sockets that are bad or there's a wiring problem, fuses don't just blow on their own.
Also, if they're both burnt out, it could be the ambient light sensor whether it's disconnected
or it's just a faulty sensor.
Now that I've talked to you about daytime running lights on GM vehicles you're gonna
notice all over the place every other GM vehicle with a daytime running light out and you're
gonna know how to fix it.
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