S80 AWD V8-4.4L VIN 85 B8444S (2008)
The air conditioning (A/C) pressure sensor detects the pressure in the high-pressure side of the air conditioning (A/C) system. See also: Function,
B8444S See: Description and Operation/Engine Control Module (ECM)/Function
The sensor is linear. It is grounded in the control module and supplied with a 5 Volt current from the control module. A linear signal (between 0-5 V
depending on the pressure in the air conditioning (A/C)) is transmitted to the control module. Low pressure produces low voltage, high pressure produces
high voltage. The air conditioning (A/C) pressure sensor is affected by the pressure in the high-pressure pipe of the air conditioning (A/C) system
(narrow pipe).
The engine control module (ECM) can diagnose the air conditioning (A/C) pressure sensor. The sensor value can be read off using the diagnostic tool.
Accelerator pedal (AP) position sensor
The function of the accelerator pedal (AP) position sensor is to provide the engine control module (ECM) and central electronic module (CEM) with
information about the position of the accelerator pedal. This data is used by the engine control module (ECM) to deploy the shutter in the throttle unit to
the correct angle.
The accelerator pedal (AP) position sensor consists of a plastic housing with two potentiometers, and an Analog/Digital converter. The potentiometers
are connected to a common shaft which is affected by the position of the accelerator pedal (AP). The output signals are a pulse width modulated (PWM)
signal and an analog signal related to the accelerator pedal (AP) position.
These signals indicate the position of the accelerator pedal (AP). The pulse width modulation (PWM) signal is transmitted to the engine control module
(ECM). The analog signal is transmitted to the central electronic module (CEM) and on to the engine control module (ECM) via the controller area
network (CAN).
Normally the pulse width modulation (PWM) signal is used to regulate the throttle angle. In the event of a fault in the pulse width modulation (PWM)
signal the analog signal is used as a replacement, unless this is also diagnosed as faulty.
The sensor is supplied with 12 V by the system relay via a fuse and is grounded to the body.
The pulse width modulation (PWM) signal is also used in conjunction with the analog signal for accelerator pedal (AP) position sensor diagnostics. The
accelerator pedal (AP) position sensor signals can be read using the diagnostic tool. A diagnostic trouble code (DTC) is stored if the engine control
module (ECM) detects a difference between the analog and pulse width modulation (PWM) signals. The engine control module (ECM) then uses the
signal with the lowest value for regulation.
The accelerator pedal (AP) position sensor is located on the accelerator pedal bracket.
Outside temperature sensor
