Cal. Veh. Code § 40806

In the event a defendant charged with an offense under this code pleads guilty, the trial court shall not at any time prior to pronouncing sentence receive or consider any report, verbal or written, of any police or traffic officer or witness of the offense without fully informing the defendant of all statements in the report or statement of witnesses, or without giving the defendant an opportunity to make answer thereto or to produce witnesses in rebuttal, and for such purpose the court shall grant a continuance before pronouncing sentence if requested by the defendant.