Crankshaft sensor

[5.7L oldsdiesel]

I'm new to repairing electronic 6.5 diesels,and i'm curious about the crankshaft sensor.Whats its purpose on the 6.5?I understand the principle on a gasoline engine,but on the diesel it seems different.The dieselpage is just great.I love learning about this kind of thing.Also,i see a map type sensor on the firewall above the hydro-booster and a similar sensor on the intake manifold which is a baro sensor?The sensor above the hydrobooster....what is its purpose?Sorry for all the questions,but i guess i'm curious about this kind of thing.

Any input is greatly appreciated.

Thanks everyone.

[rjschoolcraft]

The one on the firewall is the BARO sensor. On F engine trucks, it measure atmospheric pressure. On S engine trucks, it measures egr pressure.

The crank position sensor lets the pcm know where the crank is and how fast it's turning.

I'd highly recommend getting a set of the factory service manuals. They will be a huge help.