Auto Headlights Won’t Turn Off

[galaxy]

Uugghhh…my headlights won’t turn off in auto. On full time, regardless of sunlight. AND…this started immediately after getting a new windshield put in. Symptom literaly surfaced on first drive.

What can I check? The window install went uneventful and I watched the entire thing. I don’t see any reason the windshield job should/could be the problem.

What to check???

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[Inthehighdesert]

All down hill from there. Time to sell the car and get out why you can.


Sorry, can’t help other then being a smart …. . That’s a new one.

 

[JAJ]

Uugghhh…my headlights won’t turn off in auto. On full time, regardless of sunlight. AND…this started immediately after getting a new windshield put in. Symptom literaly surfaced on first drive.

What can I check? The window install went uneventful and I watched the entire thing. I don’t see any reason the windshield job should/could be the problem.

What to check???

A friend of mine had this exact problem with her SUV. I offered to check it out and, there was her hat sitting smack in the middle of the dashboard tucked forward against the windshield. I moved her hat off the sunlight sensor and all was well. So, take a good look at the little square sunlight sensor on top of the dashboard. Here's mine (hint - it's not the Garmin baseplate stuck to the glass):

 

[galaxy]

LOL…thanks JJ for helping me think of everyring, but the sensor is not obstructed. It looks fine.

 

[galaxy]

Is it possible the vibration from the cutting tool knocked something loose with that sensor? There’s no nicks or scuffs on it from being hit or bumped by anything.

If that sensor is damaged or unplugged, that would default the lights to on instead of off?

Does that center dash piece pop off to access it to check for something?

 

[JAJ]

Is it possible the vibration from the cutting tool knocked something loose with that sensor? There’s no nicks or scuffs on it from being hit or bumped by anything.

If that sensor is damaged or unplugged, that would default the lights to on instead of off?

Does that center dash piece pop off to access it to check for something?

Interesting question - do the headlights go off if you turn the headlight switch to "off"? They should because the "autolamp" function is disabled then. If they stay on, then something more fundamental may be happening.

If that works correctly, and you have Forscan, use it to check for BCM trouble codes.

As for which problem the sensor might have, from my quick read of the "autolamp" test procedure in the service manual, regardless of what's wrong with the sensor, the headlights will be on continuously. Presumably that's a safety measure so a failure while driving in the dark doesn't turn off your headlights.

In any case, replacing the sensor is pretty straightforward. Use a "non-marring" pry tool to pry the sensor out of its hole, pull it up, release the connector, plug in a new sensor and snap it back into place. I know this works because I've done it, although that was part of installing a Tech Pack Sync3 setup in my Track Pack car. As for non-marring, I just put some masking tape along the sides of the sensor to protect the dashboard finish and used a plastic upholstery tool.

 

[galaxy]

Headlight switch works compeltely normal; minus when you go to auto, lights come on and stay. I don't have Forscan, unfortunately.

 

[ZXMustang]

Same thing for mine. Rain sensor was unplugged. Plugging it back in, auto headlamps starting working again. Same thing, I just had windshield replaced too.

 

[JAJ]

Headlight switch works compeltely normal; minus when you go to auto, lights come on and stay. I don't have Forscan, unfortunately.

Well, then, you can replace the sensor and see if that helps. IIRC, 2017's came with dual automatic temperature (climate) control. If so, the sensor PN is DG9Z-13A018-E. This gizmo is a dual-function sensor that sends signals to the BCM to manage the headlights as well as sending voltages to the FCIM showing the sun-load on the car as part of the dual auto climate control. If your climate control is behaving strangely, it might be a clue about the sensor. By strange, what I experienced before I replaced my sensor was that I had to manually adjust the A/C settings if I went from a cloudy are to a sunny area. With the new sensor, one setting works for both.

 

[ZXMustang]

Same thing for mine. Rain sensor was unplugged. Plugging it back in, auto headlamps starting working again. Same thing, I just had windshield replaced too.

To expand on this, Anything in the top center of the windshield not plugged in or working correctly, will stop the auto lights from working. Pull down the plastic cover around the rearview mirror and check all the plugs make sure they are all snapped in. Anything out and it will stop them from working. Its not the ambient light sensor on the dash.

 

[galaxy]

Funny enough, obviously the mirror had to come off for the winshield replacement. There's only one plug into the mirror, and that's in place fine. But, there's a little plastic cover type thing that cover's the wiring from the mirror to under the headliner. For the life of me, I can't figure out how to get this thing back in place. Now, it makes no sense this would be the issue, but I'll poke around and see if anything else is out of place.

If anyone could snap a picture of the wire cover so I can see hwo to get that back in, that would be great also. Thanks guys.

Where's the rain sensor located? (edit...there shouldn't be a rain sensor on 350 since no auto wipers).

 

[ZXMustang]

Funny enough, obviously the mirror had to come off for the winshield replacement. There's only one plug into the mirror, and that's in place fine. But, there's a little plastic cover type thing that cover's the wiring from the mirror to under the headliner. For the life of me, I can't figure out how to get this thing back in place. Now, it makes no sense this would be the issue, but I'll poke around and see if anything else is out of place.

If anyone could snap a picture of the wire cover so I can see hwo to get that back in, that would be great also. Thanks guys.

Where's the rain sensor located?

The plastic cover just snaps in. There is a center part that has to unsnap to get it back in and out. Then you can put the center piece back in.

 

[JAJ]

Funny enough, obviously the mirror had to come off for the winshield replacement. There's only one plug into the mirror, and that's in place fine. But, there's a little plastic cover type thing that cover's the wiring from the mirror to under the headliner. For the life of me, I can't figure out how to get this thing back in place. Now, it makes no sense this would be the issue, but I'll poke around and see if anything else is out of place.

If anyone could snap a picture of the wire cover so I can see hwo to get that back in, that would be great also. Thanks guys.

Where's the rain sensor located?

I think @ZXMustang nailed it!

Here's what the maintenance manual says about the wiper controls:

Wiper Activated Exterior Lamps

When the headlamp switch is set to AUTO, the BCM turns the exterior lamps on within 10 seconds of the windshield wipers being activated by the wiper/washer switch. Approximately 60 seconds after the windshield wipers turn off, the BCM turns the exterior lamps off.

If the rain sensitive wipers are activated by moisture detected on the windshield when the headlamp switch is in the AUTO position, the BCM turns the exterior lamps on after a time delay. Shortly after the rain sensitive wipers are deactivated (moisture no longer detected on the windshield), the BCM turns the exterior lamps off after a time delay.

 

[galaxy]

Is that the rain sensor on the front of the rear view mirror?

Dash sensor is all plugged in good. Mirror is all plugged in good. There's only one plug on my mirror. Up under the headliner and such, where that one set of wires runs, there's no additional connections close by.

 

[Snakebyte]

This might be a good case for calling the windshield folks back to do the job right...or maybe determine if their supplier's rain sensor is defective. Regardless, it is not a problem you created and not your responsibility to fix; it is theirs.

Calling them back out could be a learning experience for them to realize they need to do the job right and have good quality parts the first time, ensuring future customers are less likely to have the same problem.

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