Harrison threw 25 pitches at roughly 80 percent with no pain.
The 24-year old left-hander had tried to pitch through pain in the past, but has decided to take a different approach this time around.
"It's May, I guess I don't want to rush it right now," Harrison said. "Take it slow and make sure it's healthy right now. If I try and push I'm going to have the soreness again, the same thing I had before."
In 2009 Harrison was limited to just 63 1/3 innings before undergoing season ending surgery to remove a rib in order to alleviate pain in his shoulder -- diagnosed as thoracic outlet syndrome.
Harrison -- 1-1 with a 5.29 ERA in 2010 -- will likely throw again in a couple days at closer to 100 percent velocity. He is eligible to come off the DL on May 22, when the Rangers take on the Cubs.