Volvo EC330B-EC460B Before IECU Engine Start & Stop Circuit

Volvo EC330B-EC460B Before IECU Engine Start & Stop Circuit

Engine start and stop circuit
If battery disconnection switch is off position, we cannot use the whole of electric system.
When master switch (Battery disconnection switch) is ON, we can use Room lamp, diesel heater, fuel filler pump, DC-DC converter, Auto greasing system without the key.
When the start switch is ON position,BR signal turn on the battery relay. From now, we can supply the power to the whole of electric system.

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ACC signal send ON signal to VECU, air-conditioner and energize EMS power relay. And Power supplied to instrument panel pass through the charge- warning lamp and goes to alternator terminal D and magnetizes the field coil.
When the start switch is START position,R2 signal goes to V-ECU to inform the key position and C signal activate safety start relay so power from battery can drive the starter. From this, alternator can produce electric power. W signal from alternator indicates engine status to the instrument panel IC.

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Start inter-Lock function
If safety start relay has some level of signal from alternator or safety lever, it cannot have ground connection to activate this relay.
There are two diodes that are related with battery relay.
One is used for time delay function of VECU during the stop condition.
The other is used to protect electric system from electrical surge.

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Key switch & Master switch
(1) Key switch
In key switch, there are three positions. Off, On, Start.
(2) Master switch
To disconnect the electrical system from the batteries for protection of electrical components when welding, servicing of circuits and as a safety precaution when parking the machine.
Mounted on the battery cover.
If battery disconnect switch is turned to the ON position, the automatic greasing (option), fuel filler pump and room lamp are available even when the start switch is in the OFF position.

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