The singer, known to his fans as Emilio, told jurors in a civil lawsuit in San Antonio that he's still recovering from brain damage suffered in the 2008 accident.
The $1 million lawsuit was brought by former band member Richard Vega. The bass player was expected to testify Thursday.
Vega suffered a lacerated liver and a dislocated shoulder in the accident in which Navaira was driving.
Navaira, a year after the crash that sent him through the front windshield of the tour bus, pleaded guilty to driving while intoxicated. He took the stand Wednesday as the first witness in Vega's lawsuit against him.