Why should a driver recheck air brake function on all units after a lengthy stop where the vehicle sat with the engine off, before continuing a doubles or triples trip?

Pick an answer

1. Rechecking is required only if the stop lasted more than 24 hours
2. Only the tractor needs to be rechecked after a stop, never any of the trailers since air pressure is assumed to hold steady on its own once the engine has been shut off
3. Pressure can bleed down over time, and confirming each unit still holds and applies properly avoids surprises once underway
4. Air pressure never changes once the engine has been shut off

Correct!

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