CONTROL SYSTEM
01–40–26
FUEL PUMP SPEED CONTROL OPERATION
CHU014000140S26
• Controls the fuel pump speed control relay according to the fuel amount required by the engine.
• The required fuel amount is determined by the engine speed, battery positive voltage and the ECT.
• When the required fuel amount exceeds the fixed amount, the PCM turns the fuel pump speed control relay on.
• The circuit driving the fuel pump switches by the fuel pump speed control relay turning on or off.
When Fuel Pump Speed Control Relay Off
— Electric current flows from the fuel pump relay to the fuel pump through the fuel pump resistor. Excess load
on the fuel pump is reduced because voltage to the fuel pump is reduced by the fuel pump resistor.
When Fuel Pump Speed Control Relay On
— Electric current flows from the fuel pump relay to the fuel pump through the fuel pump speed control relay.
Voltage to the fuel pump flows from the battery because the voltage does not flow through the fuel pump
resistor. Due to this, the fuel delivery amount increases by the increase of fuel pump drive force.
Operation Conditions
During cranking
• During cranking, the fuel pump turns on for improved startability.
At low engine speed
• As less fuel is required, the fuel pump speed control relay is turned off.
At high engine speed
• At high engine speed, the fuel pump speed control relay turns on because the required fuel amount increases.
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ELECTRIC SPARK ADVANCE CONTROL OUTLINE
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• Controls optimum ignition timing according to engine operation conditions.
• The PCM determines the engine conditions based on the input signal from the sensors and calculates the
optimum ignition timing.
• Independent ignition coils are available for each spark plug.
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MAIN RELAY
MAIN RELAY
FUEL PUMP
RELAY
FUEL PUMP
RESISTOR
CHECK
CONNECTOR
FUEL PUMP UNIT
FUEL PUMP SPEED
CONTROL RELAY
CONDENSER
TO PCM
TO PCM
B+
CHU0140S083
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