Rescindment and UCs

[mikemac]

if I received a D in a non-major class in Winter quarter but am retaking the course this Spring quarter when should I contact the UCs?

You were required to contact them after the end of winter quarter to notify them about the grade

Transfers: If you add or drop a course, fail to earn a C or better in a course or enroll in a new college after you submit your application, log back in and update your information online.

If you receive an offer of admission, be sure to confirm with the campus admission office that they are aware of the deficient grade or schedule changes. Although you must notify the campus of these changes, we cannot guarantee that a campus can go back to review an application after correspondence has been received. Make sure to save a copy of your correspondence just in case.
http://admission.universityofcalifornia.edu/how-to-apply/after-you-apply/index.html

Given you didn’t do that at the time you definitely need to do it now