Auto Headlights always on, light/rain sensor failure? 2018 CX-5

[ruthrj]

Making progress! The screen has been replaced to address ghost touch. Now I can adjust settings more confidently without a phantom screwing them up lol.

As I suspected, car on Auto lights dims the display (my mother in law only noticed it when in reverse). Video attached to demonstrate that action. The HUD also dims when switching the setting in the system between Manual and Auto using the selector button behind the gear shift. Video attached for that as well.

Getting the light sensor remounted is going to fix a lot of funkiness. Bracket has shipped and waiting for it to arrive. I think I’ll use a rearview mirror adhesive to attach it to the windshield. I’ll test the brackets fit with the sensor first though.

 

[ruthrj]

Partial success, I’m calling it quits as the main issue is resolved. Auto light sensing works!

Turns out a bracket was present in the sensor. I’m guessing it was aftermarket along with the windshield and likely arrived adhered to the glass with three small hard epoxy pads. They were a pain to remove from the glass with a razor blade, but I was able to get them off without damaging the black material on the glass. The AliExpress bracket arrived today and when I went to check the fit, that’s when I found I overlooked the bracket in the sensor.

See pics of the AliExpress part vs the bracket I found in the sensor. The AliExpress bracket fit; however, it didn’t slide right in like the one I found in the sensor. I think it’s due to slight casting differences in the hooks. You’ll notice a slight bump on the AliExpress bracket hooks vs the one found in the sensor. It took a little persuasion to get it seated well before engaging the lock. I held onto the Ali part for a rainy day and proceeded with the old bracket.

I glued the bracket on the windshield using VersaChems Rear Mirror kit. It stuck well following the directions to the letter, had to hold it in place for a minute before it took good hold. I lightly sanded the bracket beforehand to roughen the mating surface. I cleaned the glass well with alcohol and a glass wipe, had to clean the sensor with a lens wipe too. I replaced the gel pad with an OEM gel sheet and installed the sensor. Alas, it doesn’t appear that the bracket is applying even pressure across the entire sensor. Only the bottom half of the gel pad is in contact with the glass. I can press the sensor against the glass, and the gel pad slowly comes off from top to halfway down the sensor surface. Big ol air gap.

The consequence? The light sensor works, the rain sensor does not. The wipers will sit put with the sensor pressed against the windshield, but they start up and start wiping faster and faster as the sensor gel comes more and more out of contact with the glass. Tried my darndest to get a good pic but the camera is focusing on the reflection.

Oh, I did have to adjust the auto light sensitivity from the settings menu. It was on Medium, but the headlights on the car popped on when started in Auto. Changing the sensitivity to another level turned the lights off. I changed it to back to Medium, the lights stayed off during this daytime test.

I’ll call that a win for now. I’ll revisit this fix if the sensor falls off again. I don’t feel like getting another pad without remounting the bracket or something.