Chrysler PT Cruiser 2001 Service Manual Supplement page 1121

14 - 34 FUEL SYSTEM
DESCRIPTION AND OPERATION (Continued)
Fig. 10 Output Speed Sensor—Automatic Transaxle
1 – OUTPUT SPEED SENSOR
AUTOMATIC SHUTDOWN RELAY—PCM
OUTPUT
DESCRIPTION
The ASD relay and fuel pump relay are located in
the Power Distribution Center (PDC) near the Air
Cleaner (Fig. 11). The inside top of the PDC cover
has a label showing relay and fuse location. They are
ISO relays.
Fig. 11 Power Distribution Center (PDC)
1 – PDC
OPERATION
The PCM operates the Automatic Shut Down
(ASD) relay and fuel pump relay. The PCM operates
them by switching the ground path for the relays on
and off.
The ASD relay connects battery voltage to the fuel
injectors, ignition coil, generator field, and the heat-
ing elements in the oxygen sensors. The fuel pump
relay connects battery voltage to the fuel pump.
The PCM turns the ground path off when the igni-
tion switch is in the Off position. Both relays are off.
When the ignition switch is in the On or Crank posi-
tion, the PCM monitors the crankshaft position sen-
sor and camshaft
determine engine speed. If the PCM does not receive
a crankshaft position sensor signal and camshaft
position sensor signal when the ignition switch is in
the Run position, it de-energizes both relays. When
the relays are de-energized, battery voltage is not
supplied to the fuel injectors, ignition coil, generator
field, and the heating elements in the oxygen sen-
sors, and fuel pump.
PROPORTIONAL PURGE SOLENOID—PCM
OUTPUT
DESCRIPTION
All vehicles use a proportional purge solenoid. The
solenoid regulates the rate of vapor flow from the
EVAP canister to the throttle body. The PCM oper-
ates the solenoid (Fig. 12).
Fig. 12 Proportional Purge Solenoid
1 – POWER STEERING SWITCH
2 – EVAP PURGE SOLENOID
position sensor signals
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