Low Beams go out when High Beams come on

I have a 96 Chevy Tahoe. The daytime running lights don't come on anymore and the low beam lights go out when the high beams come on. I'm suspecting a relay but have no idea where the supect relay is actually located on the vehicle. Doe anyone have any ideas?

I would look at the switch. Should be easy to test with a multi-meter.

The wiring diagram shows a relay in the circuit, but does not tell the physical location of the relay in the vehicle. The switch is fine.

Check out the post under Tahoe it is entitled "Day Time Running Ligths wont work. HELP!!!" Maybe someone can help you that posted in this thread.