04 Tacoma no headlights

Check the ground sides (with meter in ohms mode), green arrows as a sanity check. I assume one of the greens is the ground side of the input coil, it should be hard ground if tacoma switches power (some cars switch ground I believe). The other green should be output power to headlights, that should also be close to zero ohms because light bulbs are almost 0 ohms at low test current.

As another sanity check, check if the voltage at the coil input (one of the yellow arrows) switches on and off with headlight switch and this will confirm relay input coil side.

When you use the meter in ohm mode, make sure to switch back to volts because if you apply voltage in ohm mode it will blow the meter fuse if a $10 meter even has one - done this many times.

And make sure your understanding of the circuit matches the relay circuit if its printed on top - those chain auto stores get the parts wrong sometimes as they deal with millions of parts. I prefer to stick with Toyota parts but I know you need to confirm failure and get back going quickly.

 

Ok, i have a 98 Taco, fuse box layout different than your but relay probably the same, here are voltages/res

The 2 yellow terms always have 12v like you said.
With lights off, one of the green terms is 0 Ohms (likely the light bulbs), the other is open circuit (large ohms, likely the HL switch).
When I turn on the headligts I get some small voltages on the 2 green terms, likely some bleed through from something else but I get about 100 Ohms on the one that was open circuit before. This seems to imply that the headlights do switch the ground on the input coil to complete the circuit.
it's too bad Toyota did not put the circuit on the top of relay but you can figure it out from what I said and compare to replacement if you have the circuit.
Good luck

Edit - i got confused on the meter fuse thing, if you are on amps and you probe voltage you will blow fuse, ohms setting is OK but of course makes no sense to have meter set to ohms and measure a circuit with voltage on it.

 

So I had a guy at my work who had a voltage meter and was probing the relay and several other things, (can't really explain in detail what he did but seem to me he knew what he was doing) his ultimate determination was that he believed I got a faulty relay and therefore I got another one. However still no headlights

 

So let me Begin by saying I realize this is cheesy and not the most ideal way to go about this, however I'm coming up on inspection and I don't have time or the money at the moment, to allow this to go unresolved much longer. That said, is there any simple way?

 

Crap my talk to text cut out...
I meant to ask is there any simple way to just run wires to a toggle switch just to make the headlights functional to buy me some time until I can fix it the correct way?

 

Any pick-'n pulls in your area? Might have some in wrecked trucks.

 

Use to be a big one, which I worked at for 12 years. Owner got sick and sold. Not many good ones any more.
However you are referring to existing hard wired lights with a toggle switch?

 

I was thinking that your low beams were out, but you said you replaced the headlight bulbs. Did you use brand new bulbs?

You mentioned the high beams come on when you pull the stalk back (flash to pass). What about when you turn on the headlights and pull it back to leave it in high beam mode?

 

No, nothing in any other way. Actually pushing it forward is actually what activates the highs

 

Oh, and yes, brand new

 

Also, can't recall is I mentioned this but, the first relay I put in, worked for about 10-15 mins then cut out.
As I said, I had someone do some checking with a multi-meter, and because his opinion (not that he's a professional, but certainly seems to know A LOT more than me) was that it's likely the relay. Which I had thought to do before but had yet to find one in stock. But did find one, and this time not only didn't work, but lights never came on at all

 

Also wanted to ask, when you turn on headlight switch (with relay installed) and open the door do you get the buzzer sound? If so this would probably indicate that your stalk headlight switch is working. If not there is something wrong with coil side wiring/relay or headlight switch. I suspect the headlight switch circuit also goes through a control module which operates the buzzer because of course it also needs the door open signals. More direct way is to measure the way i said.

Look at this link below, picture on right. The power source 1 is the 12V you saw at the small pin (86) and the headlight switch closes the circuit on the coil. This causes the contact to close, power source 2 is the volts you saw on the large pin. Relays are used because its basically impossible to run heavy wires to a delicate switch.

In the picture you could jumper pin 87 to pin 30 but you better be sure those are correct pins. On mine I saw that the coil side has 80 ohms or so resistance so I don't think you would damage anything but dont guess because computer modules are $$$.

relay diagram - Google Search