Your best bet is to:
1. Consult your owner's manual: This is the most reliable source. It should have a diagram of the fuse and relay box locations, potentially even identifying the specific relay.
2. Check the underhood fuse and relay box: This is the most common location. The box is usually located near the battery, often under a cover. Look for a diagram on the inside of the cover itself. Many relays are similar in appearance, so carefully compare the diagram with the relays inside.
3. Check the interior fuse box (if applicable): Some vehicles have relays located inside the cabin. Again, check your owner's manual for the location and diagram.
4. Use a wiring diagram: A wiring diagram for your specific year, model, and engine will show the circuit for the automatic headlights and identify the relay location. These diagrams can be found online through auto parts stores or repair manuals. (Be very careful when working with wiring; disconnect the negative battery terminal first.)
Without knowing your specific S10 configuration, it's impossible to provide a more precise location. The owner's manual is your first and best resource.
