Manifold Absolute Pressure (Map) Sensor
The manifold absolute pressure (MAP) sensor is on top of the radiator and is connected to the intake manifold by a hose.
The manifold absolute pressure (MAP) sensor detects quick pressure changes in the intake manifold after the throttle. The signal from the sensor is used by the engine control module (ECM) to supplement the mass air flow (MAF) sensor when calculating injection period.
The semi-conductor sensor is grounded in the control module and is supplied with power from the control module.
The resistance in the intake manifold moves the silicone membrane in the sensor, giving a signal of 0.5 - 4.5 V. Low pressure results in low voltage, high pressure in high voltage.
The engine control module (ECM) can diagnose the manifold absolute pressure (MAP) sensor. The sensor signal can be read using VIDA (Volvo scan tool).