Can a jury consider whether a confession was voluntary or involuntary?

The court gave an instruction stating 'I have admitted evidence that tends to establish a confession by the defendant' and then told the jury that before it could consider that evidence it must determine whether the confession was voluntary or involuntary. Defendant contends that the court erred in giving this instruction because there was no evidence of any confession by defendant. People v. Nielson (1960) 183 Cal.App.2d 20, 28-29, 6 Cal.Rptr. 367, holds that the giving of an instruction on confession, where the statements of the defendant do not amount to a confession, is erroneous. There, the defendant had described to the police what happened when he stabbed a man entering his trailer at night and had signed [235 Cal.App.2d 262] a statement again describing the facts of the occurrence. The incriminating admissions were much stronger than in our case, yet they were held not to constitute a confession. The court held that the error in giving the instruction was prejudicial because 'We think from a consideration of the whole record that it is probable a result more favorable to appellant would have been reached by the jury had the instruction about confessions not been given.' (P. 29, 6 Cal.Rptr. p. 372.)