Electric Problems (headlights and windows?)

The problem started when I drove to the gas station, turned truck off to fill up, then realized it wouldn't start again due to a dead battery. I eventually replaced the alternator, since there were a few more signs pointing to that. That fixed the problem for a few days before the same thing happened. I got the battery tested and it was giving mixed results (don't know what that means), so I got a new battery. That fixed the starting issue and still hasn't been a problem.

More issues are here and staying, though. No windows will roll down except for the driver side, and my headlights won't turn on. These are the only two persistent problems I can see right now.

Someone told me it might be a grounding issue with the alternator? I don't know where to start. I'm trying not to take it to the mechanic, especially because I don't know if they're open or might close soon with all this jazz going on. Any help would be appreciated

 

The power window problem is easy. Push the square button on the drivers door arm rest.

The headlight problem is a lot more involved. If you don’t have a basic understanding of electrical circuits and the ability to read schematics, that’s going to be tough to figure out. There is no 1 fuse that affects all headlights and nothing else. However, to get started down the right track, check every light and feature in the whole truck and tell us what doesn’t work. High beams, low beams, tail lights, park lights, reverse lights, wipers, heater, AC, and everything.

 

Couple years of electrical engineering classes so I think/hope I'll be able to figure it out after a bit of staring... it's been awhile. Are you saying I should chase wire until I find a problem or do you think it could be something to do with the alternator/that system.

For the windows do you mean like a child lock? I can't even roll them down from the driver side.

 

OK, start at the headlight relay and check for power. Then go to the dim relay. The body ECU energizes those relays.

For the PW, yes, the square child lock button.

 

Problem update: Have checked all my systems. Headlights are the only things that don’t work. High beams, air conditioning, heat, wipers, spray, blinkers, tail lights, everything except for regular low beams are good.

You were exactly right with the child lock on the windows *face palm

Haven’t gotten around to using a tester to find where the headlight error is

 

It would be weird for both lights on both circuits to fail. Probably further upstream like the main relay, switch isn't activating the circuit, or the body controller is cooked which would he rare too.

 

OK, the fact that the high beams work is a huge step to eliminating a lot of the complicated stuff. Next step. Watch the green headlight indicator on the dash. It is fed from the right low beam fuse and the left high beam fuse. If it remains on when you switch to low beams, you know that there is power all the way through the right low beam fuse. If that's the case, it's very possible that it's simply 2 burned out headlights.

If the indicator goes out when you switch to low beam, then check the dim relay and both low beam fuses. Turn the headlights on and have someone switch from high to low to high, while you touch the relay. If you feel it click, you know everything rearward of the firewall is good. That doesn't necessarily mean the relay is good, just that the circuitry that energizes it is good.

 

Okay so I’m a bit confused. The indicator light does go on/stay in when turning headlights on and switching from high to low. You’re thinking the next step should be to replace headlight bulbs? I replaced them maybe a year or so ago when one went out and doesn’t it seem unlikely that would be it, especially in the middle of my other electrical problems?

 

There are a lot of cheeseball POS headlight bulbs out there. You have 2 choices. Put a voltmeter or test light on the headlight connectors, or swap in a known good bulb and see what happens. The fact that the headlight indicator remains lit indicates that everything is good all the way through the dim relay and at least the right low beam fuse. The only thing left are the wires from the fuses to the headlight connectors and the bulbs.

 

Oh, I just thought of something, this all assuming you have a US sold Taco. If you have a Canadian sold Taco that the green indicator comes on when you only have park lights on, then all this diagnosis is out the window.

 

Anyone know what this plug goes to? It's in front of the battery on a 2013 Tacoma reg cab 2.7

 

My headlight bulb


Picture of internet bulb

So what do you know, both headlight bulbs were screwed up at the same time during all that electric jazz. Thanks so much for your help! Time for some new bulbs
Edit: Thank you so much for all your help. It means more than you probably think it does because I know nearly nothing, but love the feeling of taking care of the problem myself.