2017 auto headlights stopped working (1 Viewer)

[wordj17LC]

Hey guys.. hoping someone can help. My headlights work fine manually turning on and off but the auto on/ off feature stopped working recently. I have replaced the sensor on the dash with OEM Toyota part and the dash is clear of any debris. Is there a fuse or relay that I should look at next?

I have recently had the ac worked on by Toyota (expansion valve) and also I did the recirculating door fix so I had the passenger dash disassembled slightly. Could either of those potentially caused this issue by leaving something unplugged?

 

[Zill]

There should be an auto headlight override button near your left knee in the drivers seat. Is that turned on?

 

[wordj17LC]

There should be an auto headlight override button near your left knee in the drivers seat. Is that turned on?

The only one for headlights down there that I am aware of is the auto high beam button.

 

[Zill]

Oh sorry, I thought you were referencing your high beams.

Is your headlamp mode set to auto on your stock? (Similar to this)

 

[Zill]

If so, and I’ve never heard of a 200 series turn signal stock going bad, but on other vehicles the stock does occasionally break and the system won’t know it’s in auto mode if it has gone bad. I won’t be much help diagnosing this one, though, and the turn signal stock would be a pricey part to throw the parts cannon at.

However, with the note that you recently had a Toyota dealer working on the dash, I would take it back to them and see what they say. (It might be as simple as an unplugged connector somewhere)

 

[wordj17LC]

If so, and I’ve never heard of a 200 series turn signal stock going bad, but on other vehicles the stock does occasionally break and the system won’t know it’s in auto mode if it has gone bad. I won’t be much help diagnosing this one, though, and the turn signal stock would be a pricey part to throw the parts cannon at.

However, with the note that you recently had a Toyota dealer working on the dash, I would take it back to them and see what they say. (It might be as simple as an unplugged connector somewhere)

Thank you for your insights! Unfortunately I do have the turn signal set on auto and still no luck. I’ve adjusted the sensitivity settings in the head unit as well and nothing. Blinkers and everything else work as expected. I’ll have to call the dealer and see what they have to say. I was definitely hoping to avoid going to them if possible haha!

 

[Zill]

Thank you for your insights! Unfortunately I do have the turn signal set on auto and still no luck. I’ve adjusted the sensitivity settings in the head unit as well and nothing. Blinkers and everything else work as expected. I’ll have to call the dealer and see what they have to say. I was definitely hoping to avoid going to them if possible haha!

Sorry to hear that! Hopefully they don’t charge a diag fee since it’s probably related to that previous repair.

 

[bloc]

The AC uses the solar sensor as well, but if it's not complaining I'd think that was hooked up.

I'd try to get ahold of someone with techstream and look in the AC live data to see whether the solar sensor is giving appropriate readings with increased/decreased light. If you have any club members near you they may be able to help with that.

But yes, beyond the stalk setting and the sensor on the dash I'm not sure what else could be at play.

Since the stalk doesn't control the lights directly, but does so through the main body ecu, I'd expect any popped fuses to cause other issues with vehicle operation.. but if you still want to check them they are as follows on a 16-21 LC

To Main body ECU, in the "automatic lights" EWD
10A MPX-B NO. 1 (underhood box)
5A ECU-IG (left dash)
10A ECU-ACC (left dash)

I'm assuming the main 40A fuses for the lights themselves are good or they wouldn't be working at all.

If you are familiar with a multimeter and want to do some digging to see whether the Auto switch is actually activating at the main body ecu we can do that.. but it's above some people's heads.

 

[Sandroad]

I’m 100% in the camp of those thinking it was the dash work that caused the problem. It’s extremely likely a connector was left unplugged.

 

[wordj17LC]

The AC uses the solar sensor as well, but if it's not complaining I'd think that was hooked up.

I'd try to get ahold of someone with techstream and look in the AC live data to see whether the solar sensor is giving appropriate readings with increased/decreased light. If you have any club members near you they may be able to help with that.

But yes, beyond the stalk setting and the sensor on the dash I'm not sure what else could be at play.

Since the stalk doesn't control the lights directly, but does so through the main body ecu, I'd expect any popped fuses to cause other issues with vehicle operation.. but if you still want to check them they are as follows on a 16-21 LC

To Main body ECU, in the "automatic lights" EWD
10A MPX-B NO. 1 (underhood box)
5A ECU-IG (left dash)
10A ECU-ACC (left dash)

I'm assuming the main 40A fuses for the lights themselves are good or they wouldn't be working at all.

If you are familiar with a multimeter and want to do some digging to see whether the Auto switch is actually activating at the main body ecu we can do that.. but it's above some people's heads.

Ok I’m back. Local audio video store hooked up to the car and confirmed when turning on the auto function that nothing on their computer indicated it was receiving the signal. I’m going to butcher what I am saying but when they turned the lights on manually, the computer readings increased appropriately but when turning on the auto feature it would do nothing. He covered up the dash sensor Andy covered it quickly over and over and the readings jumped from 0 to 100 instantly back and forth. His conclusion was the stalk is bad.

Replaced the stalk tonight. Didn’t work. Checked all the fuses you mentioned and they’re all good. $300+ later and still no luck. Should I give up and go to the dealer? The multimeter is definitely not an option for me I unfortunately.

 

[bloc]

Ok I’m back. Local audio video store hooked up to the car and confirmed when turning on the auto function that nothing on their computer indicated it was receiving the signal. I’m going to butcher what I am saying but when they turned the lights on manually, the computer readings increased appropriately but when turning on the auto feature it would do nothing. He covered up the dash sensor Andy covered it quickly over and over and the readings jumped from 0 to 100 instantly back and forth. His conclusion was the stalk is bad.

Replaced the stalk tonight. Didn’t work. Checked all the fuses you mentioned and they’re all good. $300+ later and still no luck. Should I give up and go to the dealer? The multimeter is definitely not an option for me I unfortunately.

Did you watch the solar sensor reading change? and it was actually instant? Mine is really gradual, and I wonder if maybe that is a sign of failure and why my AC is acting weird..

Either way, yeah without a multimeter and the ability to confirm a ground signal is getting to the correct pin on the body computer you won't be able to diagnose if that computer is getting the signal from the stalk. Unfortunately it's dealer time..

 

[wordj17LC]

I did see it and it was almost like it was glitchy. The guy working on it said it was not reading correctly at all.

Did you watch the solar sensor reading change? and it was actually instant? Mine is really gradual, and I wonder if maybe that is a sign of failure and why my AC is acting weird..

Either way, yeah without a multimeter and the ability to confirm a ground signal is getting to the correct pin on the body computer you won't be able to diagnose if that computer is getting the signal from the stalk. Unfortunately it's dealer time..

 

[bloc]

I did see it and it was almost like it was glitchy. The guy working on it said it was not reading correctly at all.

If it was responding proportionally to light it sounds like it should be working correctly.

Glitchy in what way though?

 

[wordj17LC]

If it was responding proportionally to light it sounds like it should be working correctly.

Glitchy in what way though?

If uncovered, it read zero. Covered it shot to 100 instantly and immediately went back to zero while still being covered. There was no consistency to the readings it was getting.

 

[bloc]

If uncovered, it read zero. Covered it shot to 100 instantly and immediately went back to zero while still being covered. There was no consistency to the readings it was getting.

Uncovered in direct sunlight mine went as high as 135, covered they never quite got to zero but were very close. Also it was pretty slow to respond.

Not sure if different years have different strategies on light sensor feedback though.