Give it a sniff, when working on electrical components, IE computers, control units, PCM, ECM or whatever give the component a smell many times a defective item will smell burnt. As we used to say “the magic smoke was let out” This is also useful on tranny and PS fluid, there smell can tell a lot. Our sense of hearing can also help in diagnostics as well as giving everything a quick look. You will soon discover that using your senses will lead to a quicker repair for problems and don’t forget to stick to the basics.When replacing a defective electrical component check to see why it failed, in many cases it will come back to haunt you, when a device controlled by the component fries the part again. The common items that cause a repeat failure are injectors and IAC motors. I also believe there are many coils that could have been saved by replacing the plug wires.As any tech who has been zapped lately by spark voltage can attest to there is a lot of power and it has to go somewhere