Good youtube series for troubleshooting skills

[Stonent]

There's a car repair channel called "RealFixesRealFast" that does an excellent job in my opinion of teaching troubleshooting logic that is applicable to other technical fields.  I find that a lot of people just don't seem to have the ability to conceptualize a full system and how the parts interact when troubleshooting.

One of the common themes in the channel is "Gather your evidence first" and never just throw replacement parts at an issue.



In this video he uses an automotive diagnostic tool that can graph data. The suspect part normally outputs a voltage of 0.1V to 0.9V in a continuous up and down pattern with 0.5V being the midpoint.  But when he tests it, it never goes above 0.3V.

But he's still not completely convinced so he wants to gather more evidence. The data that he has been getting is data the computer reports it is reading but not actually the raw data from the sensor.



So here you see from the Fluke 87 V it is showing the full range of 0.1V to 0.9V before it gets into the car's computer.  But the computer never reports higher than 0.39V.

So what's next?



So he checked with another tool and it confirmed that the input voltages are within range, but it isn't reading them correctly.  When logical devices do illogical things, what could that mean?  Possibly an issue with an ADC inside the car's computer. But that's an expensive part to replace.  ADCs need good reference points so he makes sure that all the wires going into the computer have proper voltages.

Finally, the conclusion: