Here's a link to a pdf file containing the headlight wiring diagram for your year model Dodge Ram 1500..
I can't help but notice that you say you've replaced the headlight relay? That's quite odd, because there is NO headlight relay on this vehicle- only a 40 amp fuse located in the power distribution box that sits behind the battery inside the engine bay.
The switch is notorious for burning out because there is NO RELAY on this vehicle, and there is a recall (#819) but this only affects 3500 models even though the headlight wiring is the same for 1500,2500 and 3500 model Rams.
Here are two more links that will help you troubleshoot your headlights problems.
HereInformation on Putting a Relay in the Wiring System
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