automatic headlights not working....

[lisach]

I have read through all the posts I could find on this issue with no success.
2000 Yukon Denali with the DRL and Auto Headlights. During the daylight the dash indicator says the DRL is on. But there are no lights on whatsoever. I can turn the headlights on and off using the switch and switch between high and low, no problem.

When it gets dark, and the automatic headlights should come on, the DRL indicator still shows on the dash, the dash lights up and all lights come on EXCEPT the HEADLIGHTS. I CANNOT turn the headlights on manually at this time.

I have tried locating the sensor based on locations other people have said but am unable to locate it.

I have tried pressing, holding, tapping the dome light override button 4x 2x 6x 8x.

I can not get the headlights to turn on at all after dark.

NOTE: if I press the E-brake then turn the ignition switch on after dark. the DRL is overridden and I can turn on the headlights. let the E-Brake off and the DRL comes on...lights go off.

Any suggestions where to go next? And can anyone tell me, show me, the exact location of the auto headlight sensor on a 2000 Yukon Denali?

Thanks in advance
"Stuck in the Dark"

 

[01ssreda4]

Usually they are on top of the dash, perhaps near a defrost vent. I'm guessing based on my Camaro.

 

[lisach]

thank-you but alas not. Nothing that is noticeable except bolts

---------- Post added at 12:46 PM ---------- Previous post was at 12:46 PM ----------

I am hoping someone will take a photo and show me what they look like.

 

[greenhornet]

The 2 rounded bolts in the middle vent opening top of dash by the windshield, I am sure are the light and sun load sensors.They are blackish rounded domes ,the left one is the DRL/AHL sensor and the right one is the sun load sensor for the auto climate control.

 

[lisach]

Well thank you! I will look VERY closely in the morning. All I remember seeing in the vents on the dash, close to the windshield are hex head bolts but I will look again and let you know!

 

[lisach]

I have looked all over the dash and I can find no rounded bolts only 3 hex head bolts holding the defrost grill in place.

Does anyone know exactly where the daylight sensors are on a 200 GMC Yukon Denali?

 

[kses123]

I think it is located in the rear view mirror in the pre-2001 models. The mirror has two connectors. The smaller one is for the automatic headlights (if I remember correctly).

 

[ccapehartusarmyINF.(ret)]

usually what happens here in arizona is most people go buy dash mats and unknowingly cover up the sensor on the dash

 

[kses123]

Her sensor is built into the rearview mirror.

 

[lisach]

YEAH!!!! Found it!! Thanks to all who patiently worked through this with me.

Now.. the sensor is correctly sensing the difference between light and dark but not controlling the headlights correctly.

• cover the sensor: the DRL indicator on the dash lights up, dash lights turn on, all running lights turn on but the headlights don't turn on
• uncover the sensor: DRL indicator on the dash lights up, dash lights turn off, running lights turn off, but the headlights don't turn on
• apply the E-Brake: (to bypass the DRL system) turn on the ignition and headlights work correctly using the switch.

I guess I need to find a schematic or wiring diagram for the DRL Automatic headlight system to see where the control command for the headlights comes from. Maybe a DRL-headlight sensor that receives the command from the daylight sensor???? It must be a different command than what is received from the switch since that works correctly.

Found the diagram in the link from the other thread. This will take me a while to decipher and test out. Again.... Thanks to all who worked through this patiently with me. I'm not a mechanic. Just determined to figure it out.