Here's the law
https://www.dmv.ca.gov/portal/dmv/de...1/c12/a1/23123
The law is on your side, though you'll likely lose the TBD if the officer submits anything.
The operative case here is People v. Spriggs. The ruling held that using the map feature is not a violation of 23123 VC:
In sum, based on the legislative history of section 23123 and the statute's language, as well as the Legislature's subsequent enactments of sections 23123.5 and 23124, we conclude that section 23123(a) does not prohibit all hand-held uses of a wireless telephone. Instead, it prohibits “listening and talking” on the wireless telephone unless the telephone is used in a hands-free mode. Accordingly, Spriggs did not violate the statute when he held his cellular telephone in his hand and looked at a map application while driving and his conviction must be reversed.
People v. Spriggs, 224 Cal.App.4th 150, 168 Cal.Rptr.3d 347 (Cal. App., 2014)