Final answer:
When troubleshooting the air shift system, the engine should be turned off after building normal vehicle air pressure.
Step-by-step explanation:
When troubleshooting the air shift system, the engine should be turned off after building normal vehicle air pressure. This is because the air shift system relies on air pressure to operate properly.
If the engine is left running while troubleshooting, it can affect the accuracy of the air pressure readings and make it more difficult to diagnose and fix any issues.