Chrysler Stratus RHD 1999 Electronic Service Manual page 968

JA
DESCRIPTION AND OPERATION (Continued)
• Speedometer
• Speed control
• Daytime Running Lights (Canadian Vehicles only).
AIR CONDITIONING CLUTCH RELAY—PCM
OUTPUT
DESCRIPTION
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.
OPERATION
The PCM controls the air conditioning clutch relay
ground circuit. The A/C clutch relay coil side contains
a 10 amp fuse between the buss bar in the Power
Distribution Center (PDC) and the relay. The power
side of this relay is fused with a 40 amp fuse. 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.
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. 23). The inside top of the PDC cover
has a label showing relay and fuse location.
OPERATION
The PCM operates the Automatic Shut Down
(ASD) relay and fuel pump relays. The PCM operates
them by switching the ground path for the solenoid
side of the relays on and off.
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 coil 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 fuses are located in the PDC. Refer to the
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
Fig. 23 Power Distribution Center (PDC)
ignition switch is in the Off position unless the 02
Heater Monitor test is being run. When the ignition
switch is in the Run or Start position, the PCM mon-
itors the crankshaft position sensor and camshaft
position sensor signals to determine engine speed
and ignition timing (coil dwell). If the PCM does not
receive the crankshaft position sensor and camshaft
position sensor signals when the ignition switch is in
the Run position, it will de-energize the ASD relay.
PROPORTIONAL PURGE SOLENOID—PCM
OUTPUT
DESCRIPTION
The solenoid attaches to a bracket near the front
engine mount (Fig. 24). To operate correctly, the sole-
noid must be installed with the electrical connector
on top.
OPERATION
The EVAP purge solenoid regulates the rate of
vapor flow from the EVAP canister to the throttle
body. The PCM operates 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 proportional purge solenoid operates at a fre-
quency of 200 hz and is controlled by an engine con-
troller circuit that senses the current being applied
to the proportional purge solenoid and then adjusts
that current to achieve the desired purge flow. The
proportional purge solenoid controls the purge rate of
fuel vapors from the vapor canister and fuel tank to
the engine intake manifold.
FUEL SYSTEM 14 - 39