Cal. R. 3.1591
When a factual issue raised by the pleadings is tried by the court separately and before the trial of other issues, the judge conducting the separate trial must announce the tentative decision on the issue so tried and must, when requested under Code of Civil Procedure section 632, issue a statement of decision as prescribed in rule 3.1590; but the court must not prepare any proposed judgment until the other issues are tried, except when an interlocutory judgment or a separate judgment may otherwise be properly entered at that time.
If the other issues are tried by a different judge or judges, each judge must perform all acts required by rule 3.1590 as to the issues tried by that judge and the judge trying the final issue must prepare the proposed judgment.
A judge may proceed with the trial of subsequent issues before the issuance of a statement of decision on previously tried issues. Any motion for a new trial following a bifurcated trial must be made after all the issues are tried and, if the issues were tried by different judges, each judge must hear and determine the motion as to the issues tried by that judge.
Cal. R. Ct. 3.1591