There are numerous write ups on this mod. did you see how many volts are at your headlight plug before you installed the relay? It would have been something like 10.8 with the relay install you get 12 or better. I have done this mod on most of my trucks. The 98 I had I installed a relay to make all 4 lights come on W/high beams and on my 04 you can place a diode the under hood fuse box and all 4 come on also.
I can't rember where I bought mine from, but they sell real nice plug in pigtails for the STD relay. Maybe NAPA
Steve