high beams kill lows

Hey there! This is my first post here so what’s up! Anyways, my high beams whenever i throw em on kill my headlights completely and I have not messed with anything lately. I’m curious if anyone knows anything about this, thanks!

 

@crashnburn80

 

Your thread title and post info don't exactly jive

To clarify, when your low beams are on and you turn on the highs, it kills all headlights?
Or when your low beams are on and you turn on the highs it turns off the lows and keeps the high beams on?

 

Since you have a 2014 (2nd Generation) Tacoma, you have 9003/H4 dual filament headlight bulbs. You can only run one filament at a time - high or low beam - due to the amount of internal heat generated. So when you go from low beam to high beam, you switch filaments. You don't get both. If you have functioning low beams and the headlights go out completely when you switch to the high beams, the first thing I'd check is the bulbs. It is indeed possible to blow both high (or low) beams at the same time.

You can also check the fuses. The high beams are run through fuses 17 & 18 in the fuse box under the hood.

 

First step, change the bulbs to eliminate one possible cause.

 

Didn’t think i’d get this many replies this is awesome! Thanks guys. So far i’ve replaced the fuses and relay and nothing. I’m going to replace the bulbs today and if that isn’t it I think i’m gonna resort to the whole switch.

 

Oops my bad. Yes the first thing you said, when i turn highs on ALL lights are killed, accept the DRL of course.

 

It's normal for the low beams to turn off when you turn the high beams on, so that in and of itself isn't alarming to me. It sounds like you're on the right track with your troubleshooting. When you move the stalk to turn on the high beams, does the blue light on your dash come on? If it does that would lead me away from the switch and towards the bulbs or the wiring to the bulbs. Do you have a multimeter? You can check at the fuse to see if you've got 12v to ground on both sides of the fuse with the high-beam switch on. If you do, next check voltage at the plug to the bulb. If you don't, your problem is going to be somewhere else

 

I'd replace the bulbs. As people have mentioned, it is normal for your low beams to go out when your highs come on. It's possible the high beams are burned out and you never noticed until they were both burned out.

 

I’m gonna be as polite as I can. Buy a Gaw Dam multimeter. I get so sick and tired of people saying, I replaced the fuse and the relay, and next I’m gonna try________. Diagnose the Gaw Dam problem. It’s not that difficult to understand. In order for ________ to work, it needs voltage. If there’s no voltage there, backtrack till you find voltage.

 

I have a Fluke Multimeter. What's a Gaw Dam multipeter??

 

The process you're using is called "throwing parts at a problem" and it isn't generally looked at as the most effective way to solve a problem. (It is however a very efficient way of making your local parts store profitable.) What you should really do is identify the root cause problem, then address it with repairs or new parts.

Another problem with throwing parts at problems is the possibility of you replacing non-defective (generally) higher quality OEM parts with (generally) lower quality aftermarket parts. That generally just insures future problems. As @Muddinfun has already correctly suggested, a simple test light or DVM is invaluable in trouble shooting electrical problems.