28-05-15, 11:27 PM
Just to put a few things straight here in a simple format. For the purpose of the explanation the earth and negative (black) of the battery mean the same and the power and positive of the battery (Red) mean the same
The side stand switch is part of the circuit which supplies an earth to the ECU. If the ECU does not see this earth it will not fire the coils and therefore without spark at the plugs the engine will not start.
If the side stand is down this earth is disconnected, but if the bike is in neutral the earth for the ECU is now supplied by the neutral switch and the engine will start.
If the bike is in gear and the side stand is up, pulling in the clutch lever the clutch switch (located at the lever) provides a bypass path for the earth and the engine will start.
If the side stand is down and the bike is in gear the earth to the ECU is broken and bike will not start, as this stage pulling in the clutch will not help as both the earth via the neutral switch and the earth via the side stand are disconnected.
To prevent the engine turning over and not starting when this earth is disconnected from the ECU, the same earth supplies the starter motor circuit. Therefore if this earth is disconnected like the scenarios set out above not only will the engine not start, but the starter motor will not turn.
The circuitry for the above is contained in a little black box with 16 wires plugged into it called the "starting circuit cut-off relay".
This box also contain the fuel pump relay.
If we follow this earth after the starting circuit cut-off relay it goes to the ignition switch and from the ignition switch to the ECU, thus turning off the ignition does 2 things:
1. Disconnect power to the electrical circuits (except the clock)
2. Disconnect the earth to the ECU
Turning on the ignition does the following:
1. Connects power to the electrical circuits via the fuses
2. Connects the earth to the ECU
The "kill switch" switches on and off the power supply to the starter motor circuitry and the fuel pump relay in the starting circuit cut-off relay and the coils.
Back to Noggythenog problem, it seems the starting circuit cut-off system is working correctly from his description and the kill switch is working (starter motor works) this means the problem must lie between the starting circuit cut-off relay and the ECU which points to the ignition switch.
However there are a few other things which affect starting outside the control of the starting circuit cut-off relay circuit and they are:
1. Crank sensor
2. Cylinder Identification sensor
In this case it is unlikely that the electrical supply to the injectors is the problem as it would be extremely rare for all four to stop working.
It is always wise to check out the wiring and connectors for damage or corrosion before resorting to swapping items as his problem could be a loose connection, damaged wire or connector corrosion.
The side stand switch is part of the circuit which supplies an earth to the ECU. If the ECU does not see this earth it will not fire the coils and therefore without spark at the plugs the engine will not start.
If the side stand is down this earth is disconnected, but if the bike is in neutral the earth for the ECU is now supplied by the neutral switch and the engine will start.
If the bike is in gear and the side stand is up, pulling in the clutch lever the clutch switch (located at the lever) provides a bypass path for the earth and the engine will start.
If the side stand is down and the bike is in gear the earth to the ECU is broken and bike will not start, as this stage pulling in the clutch will not help as both the earth via the neutral switch and the earth via the side stand are disconnected.
To prevent the engine turning over and not starting when this earth is disconnected from the ECU, the same earth supplies the starter motor circuit. Therefore if this earth is disconnected like the scenarios set out above not only will the engine not start, but the starter motor will not turn.
The circuitry for the above is contained in a little black box with 16 wires plugged into it called the "starting circuit cut-off relay".
This box also contain the fuel pump relay.
If we follow this earth after the starting circuit cut-off relay it goes to the ignition switch and from the ignition switch to the ECU, thus turning off the ignition does 2 things:
1. Disconnect power to the electrical circuits (except the clock)
2. Disconnect the earth to the ECU
Turning on the ignition does the following:
1. Connects power to the electrical circuits via the fuses
2. Connects the earth to the ECU
The "kill switch" switches on and off the power supply to the starter motor circuitry and the fuel pump relay in the starting circuit cut-off relay and the coils.
Back to Noggythenog problem, it seems the starting circuit cut-off system is working correctly from his description and the kill switch is working (starter motor works) this means the problem must lie between the starting circuit cut-off relay and the ECU which points to the ignition switch.
However there are a few other things which affect starting outside the control of the starting circuit cut-off relay circuit and they are:
1. Crank sensor
2. Cylinder Identification sensor
In this case it is unlikely that the electrical supply to the injectors is the problem as it would be extremely rare for all four to stop working.
It is always wise to check out the wiring and connectors for damage or corrosion before resorting to swapping items as his problem could be a loose connection, damaged wire or connector corrosion.