Garrard passed the NFL-mandated tests Tuesday and then worked out at the facility.
Coach Jack Del Rio said Monday that Garrard would start Sunday's game at Dallas if he received clearance. The Jaguars (3-4) don't have many choices.
Backup Luke McCown is on injured reserve with a knee injury, Trent Edwards has a badly sprained thumb on his throwing hand and last week's starter, Todd Bouman, injured the ring finger on his throwing hand while making a tackle after his second interception. Newly acquired Patrick Ramsey is healthy, but still learning the offense.
Garrard sustained a concussion last in a 30-3 loss to the Tennessee Titans last Monday.
Britton tore the labrum in his right shoulder Sunday at Kansas City, will have surgery and be sidelined at least four months.
Pears, a 6-foot-8, 305-pounder from Colorado State, has started 30 games since entering the league as an undrafted rookie with the Denver Broncos in 2005. After spending four seasons with the Broncos, Pears signed with the Oakland Raiders in 2009. He spent the 2010 preseason with the Raiders before being waived in final cuts.
Jordan Black will start in Britton's place, and Pears will provide depth at the position.
Information from The Associated Press was used in this report.