Join Date: May 2004
Location: Toronto, Canada
It is not a "switch", it is a "sensor". It doesn't give an "on/off" type signal. It gives a voltage that is in proportion to atmospheric pressure.
The ECU uses this information (and also from many other sensors) to calculate how much fuel to inject. This is how the fuel-injected engines compensate for altitude. At high altitude, the atmospheric pressure is lower, so it reduces fuel delivery in proportion so that the engine still runs correctly. A loss in power at high altitude is unavoidable, but maintaining the air/fuel ratio correct ensures that driveability is maintained and that the loss in power is minimized.
Helibars, MRA screen, Ohlins damper, reversed shift pattern, sorted suspension, braided lines, Michelin Pilot Power, all else stock 'coz it's fast enough!