• troubleshooting is more about methodical thinking than specific techniques, tools, or tricks
• a multimeter is extremely useful and does not have to be expensive
• carrying a few inexpensive replacement parts and tools can be helpful when attempting field repairs

There are at least two different kinds of normal. Both are important to understanding how your system is misbehaving

We've come this far in the process and this is our first attempt at doing what most people think of as troubleshooting (testing with a multimeter).

Multimeters are called such because they can make multiple measurements. For our purposes we will use them most often to measure voltage at different points of the system.

For general purpose use even cheap meters will work. Advanced users seem to prefer prosumer brands like Fluke, but those users probably aren't reading this page. [YT video: iFixIt Basic Skills - Multimeter]

Note: if you are buying a new meter it can be useful to select one with a clamp to measure current. Read the descriptions carefully; DC current measurements are usually more useful for 'dwellers, but some models can only measure AC current with the clamp. Having both abilities would be preferable. [I bought this one - secessus] [YT video: Clamp Meter Automotive Measurements]

• YT video: Simple Troubleshooting on Board - Ask The Expert with Nigel Calder. Nigel is from boatworld but his knowledge is transferable.