No low beams but hi beam indiacator light is on

Sorry tldr.

 

I do the same thing. When running high performance bulbs that push the envelope the life is already pretty short and any steps to prolong life are helpful. It isn't that starting the truck with them on is going to instantly cause the bulbs to fail, but pounding on the filaments by hitting them with fluctuating voltage at cold bulb start in their most fragile state certainly cannot be kind to bulb life. I wouldn't worry about it as much with stock long life bulbs. In the commercial truck industry, in the days before LEDs, there were products to soft start your bulbs with a gradual voltage ramp up and then maintain a constant lower level voltage to greatly extend bulb life. The soft start was important so you didn't hit the filament with instant full voltage when they are cold. Filaments almost always fail when turned on (as opposed to running for a while then burning out), as the filament is cold it has lower resistance allowing it to draw more power. As the bulb rapidly warms up, the resistance quickly increases and the filament rapidly expands. This warm up time is when the bulb is most fragile. But if you do this when starting the truck, you are then hammering on the bulb with full voltage/partial voltage/full voltage/partial voltage/full voltage, as the starter turns over, then once the truck starts a final hit with full alternator voltage. Doing this a couple times won't be the death of your bulbs, but I would expect avoiding the practice in general will result in longer bulb life.

If voltage was always constant, and you never turned the bulb off, so they don't regularly experience the hazarous warm up routine, basic incandescent light bulbs can last a very long time. The centennial light bulb has supposedly been on for 117 years. https://en.wikipedia.org/wiki/Centennial_Light

 

Few points to agree and disagree.
Cold bulb has much lower resistance than nominal so when applied full voltage the current will spike momentarly to few times more than nominal. This is the main reason for "slow start" for high watage and high voltage bulbs (most of commercial trucks run 24V). This is a hit for life of switches and connectors but not very significant anyway.

The whole discussion about startup current and cranking does not apply to 1st gen Tacoma anyway as headlights turn on independently from starting. It is not happening unles you start cranking an while cranking you would turn on lights at the same time. Unreal.

As for the shortening life of the bulb significantly when turning on and off I don't think it is true as the other bulbs are more exposed to that i.e. stop light or blinkers. The most significant factor for bulbs life is the voltage applied. There is no free lunch. Higher voltage gives better light output but the life is affected. Mostly because of evaporation of filament. See the Hella doc I linked before.

Bulb usually fail on turming on (but not always). Because the filament evaporates from the hot spots making them even hotter the effect escalates. Then when the hot spot is deep enough high startup current would melt it. Simple physics.

 

UPDATE ...


It wasnt the bulbs, they lasted 4 miles then went out again....i think its in the combo switch or the plug, wiggled the stalk and they worked, shut the truck off , when i restarted it lights were back to screwed up again ...no low beams , so gonna take it apart again today and check the harness, ill post updates...

 

It was the red with white stripped wire on the plug to the combo switch...its either loose or coroded, i fiddle with it and low beams come on ....guess ill have to order a new plug and splice it in...

 

Is it custom wiring? Unless the wiring has been modified red-white is used only for flash (turns on head relay bypassing Body ECU). The head relay can be turned on by turning light control switch to HEAD (grounding red-blue wire from Body ECU) or by grounding red-white wire through flash switch. The only difference between these two is that BODY ECU has some logic to automatically turn off lights after engine is off and you lock the car. Early models don't have Body ECU and red-blue wire is directly connected with red-white.

You mentioned in the original post that red-green is also burned. Check all wires and contacts in that connector, there may be more of loose / corroded contacts. I mentioned before, that Toyota did really crappy job on designing that circuit - with age under high amp load contacts and connectors get hot and can corrode, even burn.

By the way the same flaw is in turn signal circuit - the entire current from both turn bulbs (21W each) is running through that poor switch. That is the main reason why I switched my blinkers to LED and why I'm preparing to do the headlight harness mod (I would rather burn bulbs than the switch).

 

It could be where it's soldered to the back of the assembly. Best to remove the steering wheel, then the whole assembly comes off easily with a few screws and unhooking the wire connector under the steering column. Probably have to remove the column cover too. Maybe just removing that will allow you to inspect the wires better with a mirror.

 

I ordered the plug today from toyota , it was 10 and some change , the stealership dude had no idea if it was the pigtail or just the plastic plug with no wires, i got the part number from a previous post with the same plug from an 01 tacoma and it was the complete pig tail so monday we will see ...and you dont have to remove the steering wheel to get to the collum covers off , you just turn the wheel either way to get to the screws, just FYI... ill definatly check all the other wires but just that red with white stripe i belive is the only one that is giving me hell the burnt red with yellow doesent seem to affect my issue so who knows...

 

Also whats a good headlight harness to buy, i wanna convert this over and run lights without all the strain on the electrical

 

I was just saying to remove the steering wheel if you wanted to take the whole head light/turn signal/wiper switch assembly out, like if the wire was loose on the back where I think it may be soldered onto a board.

If you can get to where you think the problem is without removing the wheel then that good.