In a small sauce pan, mix together soy sauce, brown sugar, and jam over low heat until sugar has dissolved. Reserve 1/4 cup of sauce for basting the tenderloin while grilling. Combine remaining sauce with soda in a large plastic resealable bag; place meat in bag, and seal. Marinate in the refrigerator for at least 4 hours, or overnight.
Preheat grill for medium heat.
Lightly oil preheated grill, and discard marinade. Cook tenderloin for 15 to 20 minutes, or until an instant-read thermometer inserted into the center reads 145 degrees F (63 degrees C).
Remove meat from grill, and allow to rest for 5 minutes before slicing into 1/4 inch thick medallions.