Cell phone maintenance training modules (Diagnostic approaches and maintenance methods) is an outcome of a Ph.D Thesis titled: development and validation of cell phone maintenance training modules for national diploma students, which contains cell phone maintenance training modules and other relevant literature. This thesis is divided into five chapters: introduction, review of related literature, methodology, presentation and analysis of data and summary, conclusion, recommendation and suggestions for further research. This study was carried out to develop and validate cell phone maintenance training modules in order to educate and train individuals, national diploma students, out of school youths, unemployed individuals among others.