I am 99% sure it is the relay. I had the same problem a few months ago. Many Rodeo/Amigo owners have this issue. I fixed it myself, not that hard.

Here are a couple links to look at to get an idea how to fix it. They may be able to tell you more, but like I said, I am almost positive it's your problem.

Link #1

Link #2

Good luck,
Marc


99 rodeo 4x4 v6 80,000 miles
My Rodeo