hello, I have a 1998 Dodge Dakota, 5.9 L
I can not find the headlight relay, I checked the wiring dia and it shows a relay! The headlight switch was bad, wire almost burnt through, replaced wire and switch, where is that relay, I unpluged every relay I could see with lights on and none of them dropped out the headlight,

 

This is a diagram of the fuse box inside your dash, behind the driver's side end cap. Hope this helps.

 

Now that is service! haha