hi, I have 2005 Chevy Express 3500 cutaway van with an issue of drivers side high beam not working. I have replaced the headlights with new bulbs on both sides, checked and tested the 6 fuses associated with headlights, high beam indicator works and passenger high beam works, checked wire harness end for corrosion and loose wires, Any suggestions as to what to check next?

 

The engine compartment box, has a low beam relay and a high beam relay. According to the diagram I am looking at.

56 is high beam and 58 is low. If they are the same part number, try swapping them.

https://www.autogenius.info/gmc-sava...e-box-diagram/