Chrysler 1997 Stratus Convertible RHD Service Manual page 883

JX
DESCRIPTION AND OPERATION (Continued)
• Engine speed (crankshaft position sensor)
• Knock sensor
• Manifold absolute pressure
• Throttle position
• Transmission gear selection (park/neutral switch)
• Intake air temperature
The PCM also adjusts engine idle speed through the
idle air control motor based on the following inputs.
• Air conditioning sense
• Battery voltage
• Battery temperature
• Brake switch
• Coolant temperature
• Engine speed (crankshaft position sensor)
• Engine run time
• Manifold absolute pressure
• Power steering pressure switch
• Throttle position
• Transmission gear selection (park/neutral switch)
• Vehicle distance (speed)
The Auto Shutdown (ASD) and fuel pump relays
are located in the Power Distribution Center (PDC).
The camshaft position sensor (distributor pick-up
signal 2.5L) and crankshaft position sensor signals
are sent to the PCM. If the PCM does not receive the
signal within approximately 1 second of engine
cranking, it deactivates the ASD relay and fuel pump
relay. When these relays are deactivated, power is
shut off from the fuel injectors, ignition coils, oxygen
sensor heating elements and fuel pump.
The PCM contains a voltage converter that
changes battery voltage to a regulated 9 volts direct
current to power the camshaft position sensor, crank-
shaft position sensor and vehicle speed sensor. The
PCM also provides a 5 volt direct current supply for
the manifold absolute pressure sensor and throttle
position sensor.
AIR CONDITIONING PRESSURE TRANSDUCER—
PCM INPUT
The Powertrain Control Module (PCM) monitors
the A/C compressor discharge (high side) pressure
through the air conditioning pressure transducer.
The transducer supplies an input to the PCM. The
PCM engages the A/C compressor clutch if pressure
is sufficient for A/C system operation.
AUTOMATIC SHUTDOWN (ASD) SENSE—PCM
INPUT
The ASD sense circuit informs the PCM when the
ASD relay energizes. A 12 volt signal at this input
indicates to the PCM that the ASD has been acti-
vated. This input is used only to sense that the ASD
relay is energized.
When energized, the ASD relay supplies battery
voltage to the fuel injectors, ignition coils and the
heating element in each oxygen sensor. If the PCM
CAMSHAFT POSITION SEN- SOR
does not receive 12 volts from this input after
grounding the ASD relay, it sets a Diagnostic Trouble
Code (DTC).
BATTERY VOLTAGE—PCM INPUT
The PCM monitors the battery voltage input to
determine fuel injector pulse width and generator
field control.
If battery voltage is low the PCM will increase
injector pulse width (period of time that the injector
is energized).
BATTERY TEMPERATURE SENSOR—PCM INPUT
The PCM uses the temperature of the battery area
to control the charge rate. The signal is used to reg-
ulate the system voltage. The system voltage is
higher at cold temperatures and is gradually reduced
as temperature is increased.
BRAKE SWITCH—PCM INPUT
When the brake switch is activated, the PCM
receives an input indicating that the brakes are
being applied. After receiving this input the PCM
maintains idle speed to a scheduled RPM through
control of the idle air control motor. The brake switch
is mounted on the brake pedal support bracket.
CAMSHAFT POSITION SENSOR—PCM INPUT
The PCM determines fuel injection synchronization
and cylinder identification from inputs provided by
the camshaft position sensor and crankshaft position
sensor. From the two inputs, the PCM determines
crankshaft position.
Refer to Group 8D - Camshaft Position Sensor for
more information.
2.4L ENGINES
The camshaft position sensor attaches to the rear
of the cylinder head (Fig. 2).
Fig. 2 Camshaft Position Sensor—2.4L
The sensor also acts as a thrust plate to control
camshaft endplay.
FUEL SYSTEM 14 - 29