Just got my results back yesterday and I passed! Honestly didn't think I would after my first attempt a few months ago where I scored a 68 and needed a 75. I work at a dealership and my service manager basically told me I had until end of quarter to get certified or I'd lose the diagnostic role. No pressure, right?
What changed the second time around was actually using a structured GM practice test instead of just rereading the manuals. I spent about 3 weeks, maybe an hour a day after shifts, going through practice questions and tracking which categories I kept missing. For me it was electrical diagnostics and emissions — both brutal if you haven't touched certain platforms recently.
The study guide I used broke down the domain weightings which helped me stop wasting time on sections that only make up like 8% of the score. If you're prepping right now, I'd say prioritize the high-weight domains first. Happy to share more exam tips if anyone's deep in the study grind.