High beams stuck on

Driving my truck (2009 Tacoma TRD) home this evening, I switched on the headlights and noticed that the blue "brights" indicator on the dash was lit. I clicked the high/low switch on the column and no change, brights stayed on and blue indicator stayed on. I can turn the headlights on and off, but when on they only work on high despite the switch position. As recently as last night, I can verify that the lights were working normally and both headlamps were on (saw reflection on vehicle in front of me). I have seen many comment that both lows might be burnt out, but if that's the case I would assume that there would be no lights when in low position. I have brights in both positions.

I am a novice at this and if anyone can provide some insight, I'd appreciate the kind of clear steps you would give someone who knows nothing about how to fix this. I recently installed inexpensive aftermarket LED fog lights, but they were self contained from the battery to the switch, so no fuses or relays have been tampered with. I have googled this forum several times with questions, but this is my first time signing up to post.

 

Does the switch click when you try to turn the brights off? If not, I'd be looking at the stalk first.

 

It does click.

 

Unplug the stalk. If the they go out I'd say it's bad. If they stay on, I'd look for a bad/sticking relay.

 

I've poked around a bit, including in the "Mods & Tutorials" section, but haven't found any good tutorials to show how this is done. Any that you know of for seeing how to do that? Thanks!

 

Ok, basic trouble shooting.
Since the headlight turns on and off:
- Fuse is good.
- Headlight relay is good
- Stalk on/off switch is good
Leaves two posibilities:
- The switch in the stalk is stuck on HI.
- The DIM relay is stuck on HI.

When you turn on the Headlights with the stalk, it energizes the HEADLIGHT relay. That relay sends 12v power to the DIM relay (both control and power).
The DIM relay defaults to LoBeam without a ground from the body ECU.
If HI Beam is selected, the stalk hi/lo switch sends a signal to the body ECU telling it to ground the DIM relay coil. Thereby switching the 12v coming from the HEADLIGHT relay from the Low Beam wires to the High Beam wires.

I would swap out the DIM relay first, much easier than messing with the stalk.

Fritz

 

Have you tryed pulling the stalk towards you?
To turn on the brights you push the stalk away from you, to dim pull back and to flash pull back again.

 

The plot thickens. There is an intermittent high-pitched hum that seems to associate with the brights. Toggling the stalk will cause the noise to go on and off, off when the brights are on. Just turned the truck off and the whine kept going even with the truck not on or running. Sound like anything? Further evidence of the relay argument?

 

Well, bummer. Came down to my local Napa store and we swapped out relays (by pulling the heater relay and placing it in the dimmer slots) but the problem is not resolved. Next best thought? I really appreciate all of the help, btw.

 

I'm not up on LEDs, but if you have the stock bulbs wouldn't hurt to toss em back in and try. Not sure but just process of elimination is my thought.

 

Disconnect one headlight bulb connector and try it. Then disconnect both and try it. Low beam filament may have fused to high beam filament.

 

I'm inclined to agree Dean especially since OP mentioned they were cheap LEDs

 

I believe the fogs are led

 

10MGM, would fused filaments result in the scenario described with only high-beams working and the weird hum/whine noise emanating from around the dash/column?

This is an issue with my OEM headlights, fogs are LED but they aren't the issue (thought they were involved for a sec though).
Here's what I have so far:
Not a relay issue, not a fuse issue.
I disconnected the LEDs and the problem resolved. We thought that it was how they were grounded. The fogs are self-contained from switch to lights, with fuse and relay in-line and connected to the batt terminals. They don't interact with any other wiring, but the problem stopped so okay.
Hooked everything up with the ground issue addressed and the problem came back. I completely disconnected the LEDS from switch to battery, but the problem continued. So it briefly stopped intermittently coincidentally when we tried the ground?

Am I at the point now of replacing the switch, which is both costly and laborious? I'm stumped. I did pick up a Chilton manual though, so there's that. I really appreciate the help.

 

Just as an update, the issue lasted about 24 hours. I got under the hood and disconnected the LEDs that I had recently installed, but it didn't fix the issue. I reconnected everything and it then it all worked and hasn't acted up since. The LEDs are self-contained, separate from the vehicle lights, so it's all still a mystery.

 

I have plenty of experience with this. The wiring harness on the '05 through '09 tacomas is different then the 2010s and up. Cheaper LED bulbs don't provide the correct resistance so they cannot go down the low beam. You will either have to install a resistor or get a high-dollar set of LEDs.

 

I'm guessing his issue is fixed since it happened over two years ago.

 

Holy crap that's hilarious!!!

 

I had the same issue with my 2015 two winters ago, it seemed to resolve itself after a couple of days during which I was trying to troubleshoot the problem. Then tonight my high beams came on by themselves while I was cruising down the highway and would not go off at all. I swapped both the headlight and dimmer relays when I got home with no change. I'm going to try swapping out the switch tomorrow, since I picked one up the last time they were acting up.

Here's something odd though, both times they started doing this, the weather was crappy, rain and snow. Not sure if it's related or coincidental.