回複：why i can start my stick shift(manual transmission) without p

It means your truck does not have a starter power cut-off switch under the clutch pedal, or you have one but it is faulty. On my truck, when I fully depress the clutch pedal, it will push that cut-off switch's little button in. This switch and your key are connected in serial, so you can use the key to activate the relay to supply power to the starter.

It's possible that the little button of the cut-off switch on your truck is stuck. If you know to hold the brake and check to make sure that the transmission is in neutral before you start the truck, a stuck button will do no harm. If you forget to check and try to start the truck when the transmission is in gear, it will put a lot of stress on the starter, which is not good.

The switch controls only the starter; it has nothing to do with push starting a car. When the key is in the "on" position, all the electronic devices are turned on, and you can push the truck and pop the clutch to start it with no problem.