In Genki II textbook (second edition page 114 and 115) you are tasked with creating sentences using ～時. The problem is their answers seem to contradict what is written in "A dictionary of basic Japanese grammar" (page 493).
Ex IV.A.2 shows a picture of a student not understanding something, we are supposed to create a sentence meaning "When I don't understand something I ask someone". So the order seems to be I don't understand something , and then I ask someone, which according to dictionary asks for past + 時 + present (わからなかった時人にききます), while the answer is present + 時 + present (わからない時人にききます).
Similarly, ex. IV.A.4 shows a person being homesick. We are supposed to construct a sentence meaning "When I get homesick, I call my parents", which again seems to call for past + 時 + present, and instead it's translated as ホームシックの時両親に電話をかけます.
I'm pretty sure I'm misunderstanding something.