What is the test for determining excessive damages in a personal injury action?

"It is well settled that damages are excessive only where the recovery is so grossly disproportionate to the injury that the award may be [40 Cal.App.4th 1471] presumed to have been the result of passion or prejudice. Then the reviewing court must act. [Citations.] The reviewing court does not act de novo, however. As we have observed, the trial court's determination of whether damages were excessive 'is entitled to great weight' because it is bound by the 'more demanding test of weighing conflicting evidence than our standard of review under the substantial evidence rule....' " (Fortman v. Hemco, Inc. (1989) 211 Cal.App.3d 241, 259, 259 Cal.Rptr. 311.) All presumptions favor the trial court's determination and we review the record in the light most favorable to the judgment. (Ibid.)