ENGINE <NON-TURBO>
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Control System
FUEL PUMP RELAY
The fuel pump relay supplies battery voltage to the
fuel pump. The PCM controls the fuel pump 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.
When the ignition switch is in the On position, the
PCM energizes the fuel pump. If the crankshaft
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position sensor does not detect engine rotation,
the PCM de-energizes the relay after’approximately
one second.
Along with the MFI relay, the fuel pump relay
at-
taches
to a bracket on the drivers side of the dash
panel.
AIR CONDITIONING CLUTCH RELAY
The PCM provides the ground path for the relay
coil. Relay operation is based on inputs the PCM
receives from the air conditioning switch. The PCM
deactivates the relay at vehicle start-up and also
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if it senses a part throttle/wide open throttle launch
condition. This temporarily reduces the accessory
load on the engine.
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RADIATOR
FAN RELAY AND AIR CONDlTIONING CONDENSER FAN RELAY (High, LOW)
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The PCM operates the relay based on inputs from
The PCM supplies the ground circuit for the High/
the engine coolant temperature sensor, vehicle
Low relay coil to operate the fan motor in high/low
speed sensor and A/C system.
speeds.
CHARGING SYSTEM INDICATOR LAMP
The PCM controls operation of the charging system
indicator lamp located in the vehicle’s instrument
cluster. The PCM provides a ground to complete
the lamp circuit if the charging output falls below
a specified threshold.
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The PCM also supplies the ground circuit for the
lamp circuit for 3 seconds after the ignition switch
is turned to the ON position and illuminates the
indicator lamp.
TACHOMETER
The PCM operates the tachometer on the instrument
panel. The PCM calculates engine RPM from the
crankshaft position sensor input.
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GENERATOR
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The PCM controls the generator field current to
regulate the generator output voltage to the target
voltages in accordance with the battery tempera-
tures.
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