Now, with a few sweaters in his suitcase and $500 in his pocket, he has left his Mexican-born parents to attend Grinnell College in Iowa.
He's on his own for the first time. But he isn't alone.
Jimenez is settling in the heartland with his "posse" -- nine other Los Angeles-area high school graduates who are venturing as a group to the leafy, elite liberal arts college nearly 2,000 miles from home.
There's Lauro Franco, who graduated from San Fernando High even though eight older brothers and sisters dropped out of school.
And Nakeyia Poitier, the future obstetrician whose South Los Angeles apartment lies within earshot of the Harbor Freeway.
And Steven Johnson, a gifted choral singer from Westchester High who hums Bach the way others rattle off hip-hop tunes.
The five Latinos, four African Americans and one Korean American in the group have spent months forging friendships to ease the transition from urban Los Angeles to rural Grinnell, where the closest mall is 50 miles away through countryside lined by corn and soybean fields.
"It's like taking a little piece of L.A. to Iowa," Jimenez, a Garfield High graduate whose parents don't speak English, said of his posse friends. "We can deal with problems together."
Jimenez and the others won admission to Grinnell, and full $25,000 annual merit scholarships, thanks to a little-known group called the Posse Foundation.
The national organization recruits mostly minority high school seniors who demonstrate leadership and other intangible qualities, but may lack the stellar grades and SAT scores usually required by top universities.
At Grinnell, the average SAT score of incoming freshmen this fall is nearly 1400 out of a possible 1600. Just one of Jimenez's fellow posse members came close to that.
Jimenez scored 940. But he had the intangibles that posse trainers were looking for -- drive, ambition, open-mindedness. He never questioned whether he would go to college -- only where.
At Garfield High, he was a track star (he holds the school record for the 2-mile run). He played cello and was active in the Escalera Project, which provides tutoring and helps students stay on track for college. In his senior year, Jimenez snared an internship with Los Angeles Board of Education President Jose Huizar.
Similar qualities and interests can be found in other "posse scholars," who come from Los Angeles, New York, Boston and Chicago.
Two other posses from the Los Angeles area will head this fall to Claremont McKenna College and the University of Wisconsin-Madison. In all, 223 students from the four cities are entering 22 colleges and universities, including Vanderbilt in Tennessee and Brandeis in Massachusetts.
Launched 15 years ago, the New York-based program has helped snag more than $85 million worth of college scholarships and sent nearly 1,000 high school seniors through the posse pipeline.
The posses cultivate potential young leaders who might not otherwise make it to college or tough it out once they arrive.
"I think a lot of young people have great ambitions and aspirations and then are faced with the culture shock of these isolated campuses," said Deborah Bial, 39, an education activist who started the program in 1989 after meeting a college dropout in New York who said he would have made it if he had gone with his "posse" of buddies.