As a professional, I wish more folks knew a few basics like you've mentioned. Word to the wise...you can get an OBD2 dongle on ebay for less than $10US that can talk to an android phone via bluetooth. If you have a program like Torque installed, you can read/clear trouble codes and look at live engine/transmission data. Even if you don't know much, information is power. All you have to do is plug it into the diagnostic port (usually under the dash by the driver's knee), turn the key on (start the engine if you like). A bit of research as a savvy consumer is a wonderful thing. If you have an IDevice, you'd need a wifi-capable dongle, as opposed to bluetooth (a bit more expensive, but readily available too), but the software is available and the final result is the same.