Chrysler 1997 Stratus Convertible RHD Service Manual page 889

JX
DESCRIPTION AND OPERATION (Continued)
VEHICLE SPEED AND DISTANCE—PCM INPUT
The transaxle output speed sensor supplies the
vehicle speed and distance inputs to the PCM. The
output speed sensor is located on the side of the tran-
saxle (Fig. 17).
The speed and distance signals, along with a closed
throttle signal from the TPS, determine if a closed
throttle deceleration or normal idle condition (vehicle
stopped) exists. Under deceleration conditions, the
PCM adjusts the idle air control motor to maintain a
desired MAP value. Under idle conditions, the PCM
adjusts the idle air control motor to maintain a
desired engine speed.
AIR CONDITIONING CLUTCH RELAY—PCM
OUTPUT
The PCM controls the air conditioning clutch relay
ground circuit. Buss bars in the Power Distribution
Center (PDC) supply voltage to the solenoid side and
power side of the relay. When the PCM receives an
air conditioning input, it grounds the A/C compressor
clutch relay and the radiator fan relay.
When the PCM senses low idle speeds or wide open
throttle through the throttle position sensor, it
removes the ground for the A/C compressor clutch
relay. When the relay de-energizes, the contacts open
preventing air conditioning clutch engagement. Also,
if the PCM senses a part throttle launch condition, it
disables the A/C compressor clutch for several sec-
onds.
The air conditioning clutch relay is located in the
PDC. The inside top of the PDC cover has a label
showing relay and fuse location.
AUTOMATIC SHUTDOWN RELAY—PCM OUTPUT
The PCM operates the automatic shut down (ASD)
relay and fuel pump relay through one ground path.
The PCM operates them by switching the ground
path for the solenoid side of the relays on and off.
Both relays turn on and off at the same time.
The ASD relay connects battery voltage to the fuel
injectors and ignition coil. The fuel pump relay con-
nects battery voltage to the fuel pump.
A buss bar in the power distribution center (PDC)
supplies voltage to the solenoid side and contact side
of the relay. The ASD relay power circuit contains a
20 amp fuse between the buss bar in the PDC and
the relay. The fuse also protects the power circuit for
the fuel pump relay and pump. The fuse is located in
the PDC. Refer to Group 8W, Wiring Diagrams for
circuit information.
The PCM controls the relay by switching the
ground path for the solenoid side of the relay on and
off. The PCM turns the ground path off when the
ignition switch is in the Off position unless the 02
Heater Monitor test is being run. Refer to Group 25,
BATTERY POSITIVE BATTERY GROUND AIR CLEANER PCM TCM PDC
On-Board Diagnostics. When the ignition switch is in
the On or Crank position, the PCM monitors the
crankshaft position sensor and camshaft position sen-
sor signals to determine engine speed and ignition
timing (coil dwell). If the PCM does not receive the
crankshaft position sensor and camshaft position sen-
sor signals when the ignition switch is in the Run
position, it will de-energize the ASD relay.
Fig. 20 Power Distribution Center (PDC)
The ASD relay and fuel pump relay are located in
the power distribution center (PDC) near the battery
(Fig. 20). The inside top of the PDC cover has a label
showing relay and fuse location.
DUTY CYCLE EVAP PURGE SOLENOID—PCM
OUTPUT
The duty cycle EVAP purge solenoid regulates the
rate of vapor flow from the EVAP canister to the
throttle body. The powertrain control module oper-
ates the solenoid.
During the cold start warm-up period and the hot
start time delay, the PCM does not energize the sole-
noid. When de-energized, no vapors are purged.
The engine enters closed loop operation after it
reaches a specified temperature and the programmed
time delay ends. During closed loop operation, the
PCM energizes and de-energizes the solenoid 5 to 10
times per second, depending upon operating condi-
tions. The PCM varies the vapor flow rate by chang-
ing solenoid pulse width. Pulse width is the amount
of time the solenoid is energized.
The solenoid attaches to a bracket near the front
engine mount (Fig. 21). To operate correctly, the sole-
noid must be installed with the electrical connector
on top.
FUEL SYSTEM 14 - 35