ECU help! DRL not working.

Hi, new Toyota owner since last month of a 2021 Tundra SR5. Ever since I got the truck, the DRLs have never turned on while driving. They only work with the manual selector but never work in AUTO. My truck is equipped with DRLs on headlight , there's a Drl relay, LED Drl fuse and even an option on the headlight selector to set DRLS TO OFF.... I've verified fuse is good (OHMed out), swapped the relay with another that I verief works, even went as far as placing a jumper on the relay contacts and DRLs came on. At the time of testing, I had the truck in neutral and parking break released. I have voltage all the way to the relay (green wiring) but the coil will not pick up. The next thing to check is the MAIN ECU on the uploaded diagram with the pink wire going to J165C MAIN BODY ECU. Has anyone dealt with the ECU in this format? Or how to test for the ECU? I would like my DRLs to work in auto. Any input helps
Thanks

 

Welcome to the forum.
I'm kind of surprised your SR5 has AUTO headlights at all.
That is usually an option for Limited, 1794, or Platinum Tundras.
Perhaps the 2020 and 2021 SR5 upgrades offered it.

So you have the LED headlights and not halogen, correct?
Halogen use the amber turn signal for DRLs.
LED headlights have the upper and lower white LED strips on the headlight.

Halogen


TRD Pro halogen


LED


Let's say you do have the LED headlights:
How do you get them to come on with the manual selector?
It seems AUTO would be the only way they would come on since there is no OFF selection.
If you have the parking or headlights on, the DRL strips will dim.
If you have it on AUTO, they should be bright.




Since you know that the DRLs will not come on until the parking brake is released, you could check that switch as well.



Good luck..

 

My '21 SR5 has auto headlights however they are halogen with LED lower strip DRL.

 

The OP says the DRLs don't work on AUTO, but he can make them come on with the switch.
What other setting on the switch would make them come on?

I'm wondering if he has halogens or LED headlights.

 

I really don't know, I keep mine in auto full time except when towing the camper I switch to parking lights (to power trailer rear view camera) and DRL is on both situations. Don't know what DRLs do when headlights are on as I've only driven her at night once.

 

Sorry guys... I have the Halogen with LED strip at the bottom. The DRLs work on the setting in pic below. But not in AUTO. I'm guessing the other side is not sending the ground to pick up the coil for DRLs. Is there anywhere I can locate that pink wire going to 3H on the ECU? I'm not very familiar with this. Is the 3H a wire number, pin number or harness number?

Thanks.

 

Here's a better pic of circuit

 

Update guys. Another guy in a different group suggested checking the radio settings under lighting for for the DRL to be selected to ON. That was it this whole time. DRLs work in AUTO now. I never thought that was a setting, learned something new today.
Thanks for all the input.

 

I had no idea.
We both learned something today.
Do those bottom strips dim with the parking/headlights on like OEM LED headlights?

 

Oops just discovered this and was going to suggest to check the radio settings or using the Techstream glad you guys figured out your issue.