... , tire pressure measurement. 3. Operation:1). Power on;2). Press UNIT key on the panel to shift the units (Psi ... , Bar, Kpa, Kg/cm2)3). Press LIGHT key on the panel, blue backlight turns on, it will ... input, meter will shut down automatically.4). Press UNIT key for 5 seconds, meter will reset to zero under the ... there is no pressure input.5). Press LIGHT key for 5 seconds, meter power off manually.