Which is the fuse to the headlights in a 2000 Toyota Echo OR where can I find a diagram that shows which fuse goes where in the Toyota Echo

These links show multiple fuse boxes and fuses which have something to do with daytime running light and lights.
Fuse box location and diagrams: Toyota Camry (1997-2001) - YouTube
Toyota Camry (1999 - 2000) - fuse box diagram - Auto Genius
1999 Toyota Camry Headlight Bulb Replacement, Relays and Fuses Explained - YouTube

Toyota Camry 2000 model headlight fault high beams not working xv20 Camry headlight switching off - YouTube

Toyota Camry Lights Not Working - YouTube

This is your fuse box locations and diagram. I can't think of any 'sensor' that are in a fuse box. Do you mean relays? If yes, make sure you buy proper OEM Relays and not replacements made in China. Buy from Toyota or dealership.

This shows the engine bay extra fuse boxes

https://fuse-box.info/toyota/toyota-camry-xv20-1997-2001-fuses

https://www.autogenius.info/toyota-camry-1999-2000-fuse-box-diagram/

https://www.google.com/search?q=2000+toyota+camry+le+fuse+box+diagram

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Here is the Fuse box Diagram

Toyota Camry (1999 - 2000) - fuse box diagram - Auto ...

https://www.autogenius.info > toyota-camry-1999-2000...
Jul 30, 2016 - Toyota Camry (1999 - 2000) - fuse box diagram. Year of production: 1999, 2000. Engine compartment. Toyota Camry - fuse box - engine ...

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It's your dimmer switch.

Toyota Echo rav4 headlight switch stalk replace

If you go to the gates belt site and put in the info on the car, it will show you or you can use the autozone website if you make a free account and put in the car information.

this is the main light diagram Low beam this is the diagram for the daytime running lights. hope this helps... there have bee a few reported problems with the radio blowing and then the light go out if the radio is fine it could be a fault with the LED control relay if this blows it can blow the 10amp fuse for the lights. you need to get the right relay as there are two types touch and none touch. tast one this is were all the units are

Engine bay under the hood.

there should be separate relays for your headlights inside the fuse panel under the hood drivers side fender

How do I replace the headlight Assembly on my 2000 Toyoto Echo?

No your 2000 Toyota Echo has a two belt system and I believe the belt routing diagram is under the hood near the radiator.