Cheng, 42, was taken to an emergency room, where his heart stopped early Saturday, his mother, Jeanne Marie Cheng, wrote on the website, One Love for Chi, that had been set up to support him.
He and his band mates won a Best Metal Performance Grammy in 2001, was a "powerful bassist who was larger than life on stage," the Recording Academy, the industry organization that presents the Grammys, said in a statement Sunday.
"Although the group's early years were more heavy metal-based," the statement read, "they were one of the first bands to incorporate a more alternative and ethereal sound into their thunderous and visceral music, blazing a trail that newer bands continue to follow today."
Cheng played on five albums with the Sacramento-based band.
He was ejected from a car that collided head-on with another vehicle on Nov. 4, 2008, in Santa Clara.
Despite spending years comatose, he had recently shown some signs of improvement, said Cheng's hometown newspaper, The Sacramento Bee, which first reported his death.
The vigil was planned for Sunday evening at Sacramento's Cesar Chavez Plaza.
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