PIAGGIO 500 cc, Service Manual

Page: 176 / 239

Fuel injection
9 - 64
REVOLUTIONS SENSOR
Terminals Conditions Standard
7-12 Starting speed 0,8 - 4.5 V~
The sensor allows recognition of the revolutions and the angular position of the driving shaft with reference to the
TDC. As the phonic wheel is keyed on the camshaft it is also possible to recognize the 4-stroke cycle. This solution
allows command of the injector and spark plug every 2 revolutions of the driving shaft.
The sensor is of the reluctance variation kind, and can therefore be assimilated to a alternate tension generator which
feeds the control unit.
The signal frequency is interrupted by the vacuum generated by two cogs lacking on the phonic wheel.
The sensor signal is fundamental in order to achieve engine ignition.
The engine may however function even with an unstable signal, due to corrective action on the control unit.
The total absence of revolutions signals does not cause the fuel injection indicator to light up.
When the signal anomaly (open circuit) occurs during use on the road, the indicator signals the start of the anomaly,
blinking as follows:
CIRCUIT DIAGRAM
2
1
7
23
12
CONTROL UNIT SENSOR ENGINE REVOLUTIONS 2
1
5” 5” 10”
SEC
INDICATOR ON
INDICATOR OFF