I got a 2021 fsport and Im confused, during regular operation with lights on auto and foglights off my left foglight looks on while the right one is off.

When I turn on the foglight switch the right foglight comes on and it doesnt seem like the left one gets any brighter than is was.

Do the foglights include a bulb for daytime running? If so then I assume a foglight bulb doesnt work on the left and the daytime bulb doesnt work on the right. Anyone ever experience this?

likewise if i lock or unlock my car the exterior lights all flash except the right foglight

 

Some F-sport models have a "cornering light" added to each front fog light housing. The appropriate cornering light turns on with the turn signals and is aimed to better illuminate your trajectory during a turn. Look closely to see if your fog light assemblies have 3 separate LED "bulbs", or just 1.

 

thats why im asking, its very difficult for me to tell because theyre kind of shiny/oxidized inside.


After some experimentation, if the foglights lights are enabled during the day no light comes on, they do turn on in the dark (both left and right) and then i can turn them off no problem.


so if i turn foglights on my own prior to turning the car on they sync up and if i dont then the left one comes on on its own. I wonder if there is some sort of electrical or module issue, i might start tsing at a bad relay first since its a cheap test.

 

In what country / province / state was your NX purchased?
Regulations governing front fog lights vary with market / province / state, and in modern vehicles,Toyota/Lexus adapts to these regulatory variations with software or firmware. It is possible yours has the incorrect software loaded in the body ECU, a defective body ECU, or the incorrect body ECU installed.
In the USA markets, both front fog lights are switched by the same relay, not 2 separate relays.

 

It was purchased in Canada, alberta and its originally a car for Canada. The ECU SW you're talking about not related to the one updated via usb with the cars media system correct?

 

I believe you are correct; the software (or firmware) that defines fog light operation is located within the Body ECU module, and is unrelated to the audio/media/entertainment system.

Alberta regulations ( https://kings-printer.alberta.ca/doc...s/2009_122.pdf ) Section #42-6 states:
"(6) Fog lamps on a motor vehicle must be used only at the same time the low beams on the headlamps are used."
However, section #42-7 allows fog light operation without headlights under certain conditions.

The right half of the attached drawing shows the fog/cornering light assembly used in F=sport models.

 

I was driving on the highway at maybe 70-80km/h so i doubt it was my one cornering light on , but also why does it fluke and allow me to turn all foglights off if i turn them on prior to start and driving .


Also your diagram seems to answer my q as to how many lights are in my fsport foglight assembly so thanks, but it also means changing the lights wouldnt technically solve my issue.

 

The NX owner's manual does not appear to define how and when the fog lights and cornering lights are designed to operate, so I will have to guess .
I think Lexus has designed the fog lights, for vehicles sold in Canada, to be operational only when the headlights are on.
The published Provincial lighting regulations consider cornering lights to be a type of "auxiliary driving light". Article 9 of Section 42 states the following:
"(9) A person shall not drive a motor vehicle with both auxiliary driving lamps and fog lamps lit at the same time."

I think what may be occurring is a fault in either the left turn signal or left cornering light logic/circuit. Once you start driving without first turning on the fog light switch, the left cornering light turns on and stays on. This prevents the left fog light from turning on. However, if you turn on the fog light switch before starting the car, the left fog light "wins" and inhibits the left cornering light.

Can you check if all turn signal lights and cornering lights function? Perform this test in darkness while at idle, with fog light switch off and headlights both on and off.

 

ive monitored it more closely over time and Ive noticed it is actually just working fine after drying and is occurring during the winter season and now that its drier outside it comes back to being an issue when it rains and when i run it in the carwash.

so i think my issue is more narrowed down to being a short from the water which is whats causing the left foglight to activate on its own. Might just take it to the dealer to get a diagnosis and see if the warranty i have covers it.

And i noticed this when i first bought it but i thought it was the corner light and maybe snow making the sensor come on or somethin. i bought it from a honda dealer and its been 6months so I doubt they’d even believe me or cover
it themselves.