The 26-year-old Mexican will drive alongside long-term PCM racer Alex Figge at the Florida circuit as they attempt to finalise their line-up for the 14-race series.
"I'm very happy, it's been a long off season for me and we worked extremely hard on getting everything ready for this year," said Martinez.
"I'm very excited to be able to go to Sebring with Pacific Coast Motorsports. I have always been very fond of the team, and I actually started my Champ Car career with their junior team, so it's a great feeling to be able to drive their car again.
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"This will be great opportunity to get to know and evaluate each other and build some foundation and relationships so we can start on the right foot if we end up being together for the full season this year."
Martinez made his ChampCar debut in 2006 with Forsythe, competing for them one a one-off basis in Mexico City. His two races with them last season saw him fail to improve on his career-best ninth place that he scored in his maiden race.
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