Chrysler Stratus RHD 1997 Interactive Electronic Service Manual page 1036

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DESCRIPTION AND OPERATION (Continued)
the intensity of the engine knock vibration increases,
the knock sensor output voltage also increases.
Fig. 17 Knock Sensor
MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSOR—PCM INPUT
The PCM supplies 5 volts direct current to the
MAP sensor. The MAP sensor converts intake mani-
fold pressure into voltage. The PCM monitors the
MAP sensor output voltage. As vacuum increases,
MAP sensor voltage decreases proportionately. Also,
as vacuum decreases, MAP sensor voltage increases
proportionately.
At key on, before the engine is started, the PCM
determines atmospheric air pressure from the MAP
sensor voltage. While the engine operates, the PCM
determines intake manifold pressure from the MAP
sensor voltage. Based on MAP sensor voltage and
inputs from other sensors, the PCM adjusts spark
advance and the air/fuel mixture.
The MAP sensor mounts to the intake manifold.
POWER STEERING PRESSURE SWITCH—PCM
INPUT
A pressure sensing switch is located on the power
steering gear. The switch (Fig. 18) provides an input
to the PCM during periods of high pump load and
low engine RPM; such as during parking maneuvers.
STARTER MOTOR KNOCK SEN- SOR POWER PRESSURE SWITCH STEERING
When power steering pump pressure exceeds 4137
kPa (600 psi), the switch is open. The PCM increases
idle air flow through the IAC motor to prevent
engine stalling. When pump pressure is low, the
switch is closed.
Fig. 18 Power Steering Pressure Switch
SENSOR RETURN—PCM INPUT
The sensor return circuit provides a low electrical
noise ground reference for all of the systems sensors.
The sensor return circuit connects to internal ground
circuits within the powertrain control module.
SPEED CONTROL—PCM INPUT
The speed control system provides five separate
voltages (inputs) to the Powertrain Control Module
(PCM). The voltages correspond to the ON/OFF, SET,
RESUME and CANCEL.
The speed control ON voltage informs the PCM
that the speed control system has been activated.
The speed control SET voltage informs the PCM that
a fixed vehicle speed has been selected. The speed
control RESUME voltage indicates the previous fixed
speed is requested. The speed control CANCEL volt-
age tells the PCM to deactivate but retain set speed
in memory (same as depressing the brake pedal). The
speed control OFF voltage tells the PCM that the
speed control system has deactivated. Refer to Group
8H for more speed control information.
FUEL SYSTEM 14 - 35