Did both my headlight bulbs burn out at the same time? Or is it something else...?

Went to run an errand today in my 2012 and when I turned on the truck, only the left headlight came on, but only for a few seconds before going out. The right one never turned on at all. I last used the truck yesterday and both low beams were working fine.

The high beams for both sides still work. The dash indicators for low and high beams still come on fine when I activate their respective switches. I even hear a "click" noise when turning the lows on but they don't light up.

I checked both low beam fuses, and they're fine. I swapped the dimmer relay with the heater relay (the two big blue ones) to see if the relay was at fault but it made no difference. If I remove the headlight relay (the big gray one) neither the low or high beams work and I can't hear the "clicking" noise turning those switches usually makes. So I don't think it's the relays either.

So, is it my bulbs? Did they just go out at the same time? I replaced both at the same time about 6 months ago. I thought I'd get a lot more time out of the set than that. But if a new set of bulbs fix the issue, I'm fine replacing them now. I need a functioning vehicle right now more than anything, my wife's due date is very soon!

 

Odd for both to go that close together but not imposable
If you have a multi-meter check for continuity/resistance of the bulbs to check for sure

 

What bulbs were these? I have a 2015 and I’ve tried a few different bulbs when I’ve needed replacements. It seems that the brighter they are (as advertised) the less time they last. I did have a set that only went six months.

I just recently did a replacement because the bulbs went out within about a week of each other, after one year of use. I don’t use my lights much because I don’t do a lot of driving at night…

 

Definitely possible, had it happen on a car I had about 20 years ago. Do what CraigF said or just get a new bulb and swap it

 

Take out one or both and look at ‘em. A burned out filament is usually visibly opened. And a multimeter with continuity check is always useful. Either of those is easily done.

But with neither low nor high on both sides… The high and low are separate filaments in an H4 bulb, so this would mean four filaments burning out simultaneously. I’m bettin’ it ain’t as simple as a bulb change.

 

They are the "Philips RacingVision GT200 H4" that I saw recommended in some other TW thread that I can't seem to find right now. I figured they wouldn't last as long as my last set which went for MANY years (I literally don't remember changing them, although with my 2012 I'm sure I've done it at least once, because there is no way the stock bulbs lasted over a decade, right?) but I didn't expect to have to replace them in less than a year!

I should mention, I do run with my headlights on all the time. Before anyone says "well yeah duh of course they burn out if you run them every time you run the truck" then how did my last pair last at least half a decade, back when I used to use my truck daily? (it now only gets used about 4-5 times a week)

 

It is certainly possible.
The key here is that the Low Beam indicator for the dash is illuminating.
That indicator on the dash is powered by the Right Low beam fuse. There for, the fuse should be good for the Right side at least.

The left, well, that one would be better off checked with a meter.

Actually, the plug for the headlight is easy to get to.
Just check the low beam pin for power.
Red Yellow - Left side
Red/Black - Right side

 

High beams still work for both left and right hand side. Low beams are the only ones not working.

The multimeter check is a good idea. I actually have never owned one. I suppose it's time to buy one? I assume all I have to do to check is pull off the rubber grommet thing, touch the probe to the bulb and see if there is power running to it?

Can you elaborate on this? Which plug? You mean where the actual wires plug into the bulbs? I really need to buy a multimeter and learn how to use it lol

 

Or a test light, I like to use a test for most things.
It’s “one handed” and easier to use.

 

Can you link one? I plugged "test light" into Amazon but I'm not sure if that's what you're talking about...

 

You can find them everywhere.
Even Wal-mart has them

$13 Lisle 28400 Heavy Duty Circuit Tests Low Voltage Up to 12 Volts, Factory

https://www.amazon.com/Lisle-28400-...t=&hvlocphy=9013375&hvtargid=pla-899732512456

 

I’d take a bulb out, or play with a spare, to get the hang of checking with a multimeter.

You’re not looking for voltage. (That comes next depending on what your first tests show). To start we’re looking for continuity (a continuous path for electricity to follow with no open spots in the circuit). This is tested on the bulb alone, with no power going to it. That’s why out of the car at your desk is a good place to start. For continuity the juice comes in one terminal on the bulb and out another. If it’s open the juice won’t flow. Most multimeters these days, even the sub-$10 Harbor Freight ones, have this feature and are good enough for this purpose.

The bulb from your Tacoma will have three terminals. One circuit inside is for the low beams and another for the high beams. So in a perfectly good bulb there won’t be continuity between all three terminals. I forget right now exactly which pairs you want to check, but someone will remind us and its easy to find an H4 bulb terminal diagram elsewhere.

Look at the suspect bulb too, under a loupe or magnifying glass (or smartphone camera with enlargement) to see if the filament looks OK. In an H4 bulb the low beam filament is the one underneath the little metal hood.

After you check the bulbs we’ll decide if you need to check supply voltage through the wiring.

 

I like a test light because it shows that the circuit can carry a load.
Continuity only shows that there is a connection.
You can show continuity, but still have a wire issue.

I’d use a test light at the bulb connector.
Turn the low beams on and check it with a test light.
If the test light lights up, the circuit is good.

You can also check ground the same way.

 

Hey thanks for the detailed responses, I've ordered a test light with voltage readout, and I'm going to order a new set of bulbs as well. If the bulbs don't end up being the issue, I'll just return the bulb set. But I have a feeling it's the bulbs.

 

Yes, higher performance bulbs don't last as long as OEM or "regular replacement" bulbs. But the higher performance is generally worth it.

See Post #4585:

The ultimate headlight upgrade H4 (not LED or HID) | Page 230 | Tacoma World

 

I read your original post wrong, @zul. With high beam=OK / low beam=Out there's a good chance it's the bulbs. I've had H4 bulbs burn out within a week or two of each other, but never the same day. It's definitely possible.

 

Electrical problem?

Multimeter.

All your questions will be answered and the path will be clear.

 

Maybe one burned out a short while ago and wasn't noticed as the other one was still working. Then noticed when the remaining bulb blew the filament. It happens more than you would think.

 

Step 1 is to pull the bulbs out and look at them

Check the connector too and make sure it isn't melted

 

I'd like to say that this is impossible because I'm very anal about this kind of thing and would have noticed, especially since the truck is parked in a dark garage all the time and I leave the headlights on for all driving trips since it's safer and easy because they turn off when I open the driver's door after parking...

BUT with that said my wife pays far less attention to details like this and has been driving the truck. So maybe they did burn out at different times and I only noticed when I got in it yesterday.

Yeah, I will definitely look at them once the new ones come in. I'd rather not handle them more than I have to for a couple reasons - 1st they're delicate and hard to ensure nothing touches the glass during install and removal, and 2nd, with my big hands, removing and replacing them is a huge pain in the ass, especially for the passenger side with that damn windshield washer reservoir blocking access.