1988 Toyota pickup with no low beams and no high beams . I replaced with new switch and new relay . What do I check next?

If both low and high beams are not functioning after replacing the switch and relay, check the fuses related to the headlight circuit, as a blown fuse could disrupt power. Additionally, inspect the wiring and connectors for damage or corrosion, which may interrupt the electrical flow. Finally, verify that the headlight bulbs are functioning properly by testing them directly or replacing them as a precaution.