Help! Headlight dash light issue

[ChadMonster]

I’ve got a 2019 TRD OR, bone stock at the moment. Recently while driving at night, my head lights and dash lights shut off/cut out. Turn them off then back on and they work like normal. It’s happened twice completely at random. Anyone have this happen before??? Don’t know where to start

 

[Smitty]

Never heard of that before.. Probably an electrical issue somewhere I'd take it to the dealer especially if it's still under warranty

 

[ChadMonster]

That’s what I’m afraid of. Closest dealer is an hour away. No warranty left that would cover that. Have a little bit of power train warranty left is all.

 

[Smitty]

Maybe check the fuse for the lights? If that's good switch it out anyways just to see. Also check the connections on the headlights, the plugs show below.

 

[ChadMonster]

Which fuse? There’s like 2 per side plus 2 relays…….. I was thinking possibly a bad relay as that could go into protect mode.

 

[Smitty]

Both fuses, Idk much about the fuses we have besides the one I keep blowing when I turn on my light bar and blue lights (Ik my problem I'm just lazy)

 

[ChadMonster]

Gotcha. Ya the thing has 2 per side plus a parent fuse for both. My thought is, the more I think about it, gotta be either a relay or the multifunction switch. I’ll have to drive around with my brights on and see if that changes anything.

 

[Smitty]

Lmk what you find out!

 

[ChadMonster]

Will do. My mind is leaning toward the low beam relay right now.

 

[bonifacio]

I'd say give this a try before the relay.

Check the ECU/ECM fuses. Just swap them. Easiest and cheapest thing to start troubleshooting.

I know it's a 2001, but it sounds like the same issues.

Source: 2001 Toyota Tacoma Headlights Go Out Periodically: When I'm ... (https://www.2carpros.com/questions/toyota-tacoma-2001-toyota-tacoma-headlights-go-out-periodically)

 

[ChadMonster]

Just curious, how would the ECM be in control on the headlights??
I’m not opposed to popping in new fuses but legit curious….

 

[bonifacio]

Just curious, how would the ECM be in control on the headlights??
I’m not opposed to popping in new fuses but legit curious….

Maybe it's something that's ambiguously labeled. BCM/ECU/ECM. Maybe they wired it to or through to feed power from the same source as the ECU. I dunno. Maybe the guy that posted the update on his issue meant BCM and not ECM? I guess an ECU would send signals to the dash for all your function lights. Then there are headlight and dimmer switches that are wired into/through the ECU. Then I also assume the ECU could tell the BCM when the vehicle is off. That way it know when to start the delay before shutting all the lights off. Here's my overthought out thinking as why it could be a possible fix. I'm on my no sleep kick again.

I guess the first question should have been did you buy it new or used? Have the LED headlights?

I'd say Texas Instrument is a valid source. How to flexibly configure an LED driver for automotive headlights (https://e2e.ti.com/blogs_/b/powerhouse/posts/how-to-flexibly-configure-an-led-driver-for-automotive-headlights)

Electronic technology has advanced so that an electronic control unit (ECU) is required to control the functions of full LED automotive headlights.

Going by that, perhaps it's a law or safety standard that makes it a requirement. Once that requirement was in place, I'd assume the manufacturer could have made it the same for regular halogens to simplify the manufacturing process. Why produce 2 different variations that technically do the same thing, when you can reuse molds or production lines in place and making small alterations. Which in this case could be running through the ECU.

2003 Tacoma 4cly 2.7L no daytime running lights. Same. Time interval 30 minutes. When it goes dash, high, and low go. Don't know whether rear goes or not. Off /on with rotary fixes every time so far.

Then returns 11 months later and gives everyone an update.

For posterity the culprit was a bad fuse for the ECM module. Replaced that and the headlights stay on now.

Worked for him. Might work for you. Without knowing what the cause is, I would troubleshoot with the simplest/cheapest things first.
If somehow it fixes it for you that's a win. Maybe I got it all wrong. But it's a start right?

 

[ChadMonster]

Ya thats Valid. Guess my it’s possible that the ECU/ECM might have something to do with it. Just makes a guy wonder how the ECM fuse could be bad and the truck still run…….. I’ll check that fuse (assuming it has one) and make sure.
I did by it used, second owner, old man owned for 48k miles. Factory lights as far as I know.

 

[bonifacio]

Ya thats Valid. Guess my it’s possible that the ECU/ECM might have something to do with it. Just makes a guy wonder how the ECM fuse could be bad and the truck still run…….. I’ll check that fuse (assuming it has one) and make sure.
I did by it used, second owner, old man owned for 48k miles. Factory lights as far as I know.

There might have been factory LED's in 2019. Not too familiar with recent trim packages or if they swapped them all over.
I know in 2015 my Corolla had LED headlights. The ones where if one went out, you have to swap the entire headlight.

Could always try to dig up the electrical wiring manual or whatever that's out there. It's what I used to prove to the dealership that the headlights and DRL are on a separate relay. Even then, they denied my claim. Fuck asses.

 

[ChadMonster]

Shit part for me is the closest dealer is an hour away and I’d have to schedule it in on a Saturday……….. not ideal for anyone especially since it’s and intermittent issue.
That said. Tonight, it happened again and I had a speculation that’s it’s the low beam relay. Once it happened, it flipped the highs on and they popped right on, including my dash lights.
That all but validated my thought about it being the low beam relay.
I’ll get it swapped out and see if it happens again.