Originally Posted by HappilyLost
As a noob, what are the glow plugs and how do you know if they’re on or not
Glow plugs are devices that are usually (in modern vehicles) devices that when activated heat up very quickly to aid in the combustion of diesel fuel when the engine is cold. Imagine a soldering iron tip getting red hot very quickly. Usually there is one glow plug per cylinder. Keep in mind that diesel fuel ignites by heat which usually done by high compression of fuel and air but sometimes when cold, diesels need a little extra boost in heat to get things going.
On my older diesel tractors (60's and 70's) we use a tiny bit of ether or on one tractor I have a glow plug like device that has a coil in it (looks like a spring) that gets red hot which then diesel fuel is injected onto igniting a small fire in the intake which then, while cranking, the heated air goes into the cylinders for assistance in starting.
Again speaking for modern engines (those that are computer controlled), if the glow plug(s) weren't working but being called upon by the auto's computer, it would throw a code and you'd probably get a CEL (check engine light).