Map sensor

0.2 volts on the ground wire, 5.0 volts on the supply wire, and 0.5 to 4.5 volts on the signal wire. The signal voltage when you turn on the ignition switch but before cranking the engine is stored in memory as the barometric pressure. The higher the engine vacuum, the lower the voltage will be.

5.0 volts on the signal wire means the ground wire is open. 0 volts means the feed wire is open. If you measure 0.5 to 4.5 volts at the sensor but a scanner that displays live data shows 5.0 volts, that means the signal wire is open. Anything outside of 0.5 to 4.5 volts will trigger a fault code. For a broken signal wire, a high value "pull-up" resistor in the computer insures the voltage won't float around a normal value. Rather, that insures it will go to a voltage that will set a fault code.

Caradiodoc

Black / light blue is ground for all of the sensors. Violet / white is the 5 volt feed to all of them. MAP signal wire is dark green / red. It's in the middle of the three wires in the plug.

Caradiodoc