Auto diagnostics - have a look, this is excellent

[STP]

This is a young lad from Milligan Auto Diagnostics who is a great diagnostic tech and the video illustrates great techniques to find a fault, and why I advocate for using a high power lamp (bulb) to prove a circuit can provide power (current) and not just voltage at a test meter, on a vehicle.

If you like his stuff and find it informative, like and subscribe. I can guarantee if you are a bit handy, this stuff will help you. Lots of great content. You may not have all the kit he does but the techniques for the testing will be doable with a meter and a bulb.

Great videos on fault finding (some Caddy and other VAG content too) - this one is a BMW but the techniques are the same.

This is exactly what I do for a living but on automated heavy machinery (PLC controlled) as a Controls Engineer. This lad is good.

https://youtu.be/ytwxbHiHkQw?si=0CywcVy0ybDwuDhs