The 5-step loop
Every good diagnosis follows the same loop. Do it the same way every time and you'll stop guessing.
The short version
- 1. Confirm the complaint. See it yourself if you can. "Doesn't work" isn't a complaint yet.
- 2. Check the easy stuff: switches, breakers, fuses, tank levels, battery disconnect.
- 3. Pick a test that splits the problem in half. Power there or not? Gas there or not?
- 4. Follow the evidence to one part or one connection.
- 5. Fix it, then prove it's fixed the same way you confirmed the complaint.
Shop tip
Half of all "bad parts" are a switch nobody flipped or a battery disconnect that's off.
Try it on a service call
Put the lesson to work on a hands-on troubleshooting case.