2021 TRD Pro Headlights DRL AutoDim not working

Hey everyone!

I have a small problem with my TRD PRO OEM Headlights; let me explain:

1.- Normal condition: In daylight, when the headlight switch is in "AUTO" position, the DRL turns on, at full brightness.

2.- Whenever I turn on the fog lights OR headlights (this last one manually or auto), the DRLs dim a little
bit so they do not annoy other drivers at night (AS INTENDED).

3.- After a couple days of heavy rain, my DRL do NOT dim when turning the headlights or fog lights on, frustrating others at night.

I am taking it to the dealer on Friday but, is this a common problem? I didn't find anything on this or other forums.

Could the water have damaged the dimming wire or something?

thanks in advance!

 

I haven't heard of anyone having this issue?

 

UPDATE in case anyone stumbles with this in the future:

-Now, fog lights won't turn on on the "Auto" Position in daytime (before, they did).

-SOMETIMES, DRL dimming with headlights happens, sometimes it doesn't (regardless time of day).

-SOMETIMES, starting the car with the e-break, results in DIMMED DRLs (as intended); but sometimes it doesn't. Sometimes DRL's will stay super bright even at night and starting the car with e-brake.

TOYOTA dealer checked them and said there was nothing wrong with them. No wiring issues, no blown fuses.
I showed them the video of my findings and told me to take it in again for a 2nd revision.

Any ideas?

 

In order for the Fogs to turn ON, TAIL circuit needs to be ON. Auto Lights feature would do this. (controlled by part by light sensor and the sensitivity settings.)

DRL dimming happens when low beams are ON. Again, if combination switch (light stalk) is in AUTO.(controlled by part by light sensor and the sensitivity settings.)
It's all pointing to the sensor and the ECU that controls it. (Main Body ECU)
Try not using the AUTO position on the stalk and verify the DRL's in each position of the Light stalk.

 

Thank you so much for your answer!

It sounds very accurate. I will do more testing and take it in to check exactly this.

Bonus: I originally suggested them to check the sensor and their answer was "if headlights AUTO come on at night there's nothing wrong with the sensor" sheesh.

 

Sounds like noob answer from the "mech"...

 

Caribe’s got you, so you are in good hands it is a function of the ECU to “turn off” DRL as it were, so the dimmer function is powered by the parking lights. So I would check into the ECU if it isn’t functioning correctly. The ECU is also what controls when the lights come in with the parking brake.

Just to double check though: your not running adaptor harnesses or anything?

 

Man, if I could updvote this a million times I would!

I do not think so- (sorry for my ignorance),
both the LED fog lights and headlights are OEM and were bought and installed at the dealership.