When the Power of the DinoZords had been sealed away into the earth; Jason, Trini and Zack along with the other Rangers were granted new Zords and Powers taken from the Power of Thunder! Later in the season the trio are chosen to take place in the International Peace Conference in Switzerland and therefore Zordon must chose three new Rangers to take their place.
In order to transfer the Powers, Zordon sends the Rangers to a deserted planet where the Sword of Light resides.
When the Rangers obtain the Sword, the powers are transferred and the new Rangers take their places.
Jason would later return in Power Rangers Zeo, but it is unknown what happened to Trini and Zack.