No low beams but hi beam indiacator light is on

Gentlemen,
First post , ive literally scoured forum after forum for my issue to no avail, i have a 02 tacoma v6 4×4, no drl's
Last night leaving the hospital i turned on my headlights and nada...i have hi beams with the switch foward like normal, switch pulled back , nothing just parking lights , i can hear the relay , ive replaced the combo switch and checked continuity to both the new and old combo switch per haynes manual, on the plug side of the combo switch the red with grn stripe wire is burnt at the plug, bulbs are good... i hate wiring... could this be a possible ground issue.. and if so where the flying fudge popsicle is the ground location,
Thanks in advance

 

That's you problem I think. The arrow shows the wire going from the junction box to headlight switch controlling the low beam:



When headlight relay is energized (your lights get power) which is controlled by Body ECU you get 12V at the bulb. When this red-green wire is grounded (through the switch) you have low beam ON and High beam indicator light will go off. I bet this burned wire does not provide good contact to the switch. This is high amps wire (Toyota design sucks there) meaning about 9A has to go through it.

 

Can i run a different wire from the plug end on the combo switch to???? Replace that burnt wire do ya think ??? Wiring gives me the screaming meme's ...

 

Did you try swapping for new bulbs? I had the same issue leaving work one night. Spent 30 minutes swapping fuses and checking everything. had to drive to the autocrats store with my high beams. Threw new bulbs in and it worked. It was weird that both went out at the same time, but worth a try. Hopefully its that simple for you!

 

Picture of that burned wire/plug?

 

Starting the vehicle with the headlights on can cause both the bulbs to blow out at the same time.

 

Why? Voltage spike? Battery should take care of that.

 

Odd, but not unheard of. It's more common than one might think, since headlights are used the same amount of time versus, let's say turn signals.

 

You can call it a Voltage spike depending on what your definition of that is.

 

Unless you put some serious voltage through the bulb you can't burn them in very short time, not before you burn everything else in your truck. I did start many times with lights on, and nothing bad happened - the lights of course dimmed during the cranking but that was it. So unless I see some reasonable explanation I'd call it a myth

 

Starting your vehicle with your headlights in the off position is a well-known practice to preserve longevity. Tungsten bulbs are designed ideally for an operating voltage of 13v. Higher voltage and a starting surge will prematurely demise bulbs along with handing bulbs bare handedly.

Call it a myth. I got 8 years off my last set of bulbs .

 

@crashnburn80

You're the headlight guru here.
Am I wasting my time turning off my headlights before I start my truck to preserve the life of my bulbs?

 

If both low beam bulbs were burned out the high beam indicator wouldn't work (see wiring diagram), but the OP said the high beam indicator was on, hence at least one of the low beam bulbs is not burned out.

Why don't you check for continuity first to determine if/where the wire is broken?

 

Not sure about our trucks..I had an Olds Achieva that once busted both lows at the same time and the high beams worked

 

Here is your problem: Toyota did not get the memo about the bulbs optimal voltage and designed the charging system for higher voltage ("13.9−15.1 volts with engine running at 2000 rpm and 25°C"). Or maybe they did by designing such crappy circuit for headlights with huge voltage drop on wires, connectors and switches.

But seriously I am not questioning that running bulbs at higher voltage than designed will shorten the bulbs life. It is the "starting thing" that I doubt has any impact. If there is any spike in the voltage it can't be significant because if it is it would destroy everything else in a car including dash lights and maby ECU. On the other hand if there is a slight increase of the voltage, the cranking time is to short to have any significant impact on the headlights bulb life. It is possible that this "well-known practice" came from (and may be applicable in) older cars with mechanical voltage regulator with no electronic on board.

If course "fixing" Tacoma's design flaw and running additional harness for headlights will have negative effect on the bulbs life - hence running higher voltage straight from the battery (14.4V nominal) will shorten bulbs life by a half. That is a fact.

Good info straight from the source - bulb manufacturer: https://www.hella.com/hella-za/assets/media_global/HASA_Bulbs_Catalogue_2012_LRes.pdf

 

I didn't say the high beams! I said the high beam *indicator* wouldn't work. That's because this bulb gets it's power through the low beam filaments when the switch is in the high beam position, or if there's a problem with the switch/wiring the high beam indicator will be on when the low beams should be on like the OP said.

 

Welp, it was the bulbs, i tried my old set i threw in the trash can that worked and they didnt even work, bought a new set at wallyfart and presto...so unless something had a chance to cool down or "de ground " itself the low beams work now...and the only reason i went thru this trouble was 1.the bulbs werent even a month old and 2. Everything ive read said the high beam indicator was off... mine was still on , hence the reason i didnt think it was the buld, i also just bought this truck and the previous jerk wad installed a janky alarm and aux light system , then hit a deer removed all but the wiring and i had $hit everywhere i had no idea where it led, now most of it is just dead ended so i cut away everything i thought was from the previous alarm or aux lighting...i only paid 6,000 for the truck ... its an 02 ..210000 ext cab step side, damn nice truck dont burn a drop of oil or leak..motor is tight as a drum and no slop in the ass end...so lets hope she stays good....thanks for all your help

 

Glad it was a pretty simple fix! Sounds like my truck. Mines an ‘03 ext cab bought with about 220,000 miles last year. Its just over 250,000 now and no major issues. Time to upgrade the suspension tho due to adding extra weight with a shell, RTT, and a custom drawer system. Cant beat these trucks!

 

What kind of bulbs were the last set? If someone had put LEDs in they may have rigged a circuit to bypass the low beam to make the high beam indicator come on when it's supposed to.

Did you touch the glass with your fingers? "They" say the oil on your fingers can cause uneven heating and blow them out.

If your circuit is original and is like the diagram posted above then the high beam indicator shouldn't ever be on when the low beam switch is turned on because both sides of the high beam indicator bulb are grounded, so no voltage across the bulb.

 

Sorry Tldr.