1999 Sienna Headlights Don't Work

I have a 1999 Sienna with DRL that lost all headlight function (DRL, Low Beams, and High Beams). Main fuse and individual low/high beam fuses are okay. I noticed the headlight relay wasn't energizing so I removed it to test the contacts and coil, which checked out fine. When I placed a jumper across the headlight relay contacts, the headlights were restored to full functionality and could be turned on and off from the headlight switch on the column.

I don't have access to a schematic for that model year and I would like to find out what else could have failed to prevent the headlight relay from energizing. Replacing the relay with a jumper has me up and running for the moment but I would much prefer to fix the problem properly. Any ideas on where to look next? Thanks.