No Spark Plug; Hv Primary Coil Check; Hv Coil Secondary Check - PIAGGIO 633929(IT) Service Station Manual

MP3 125
To avoid disturbances in the ignition system during start-up, it is very important that the engine-chassis
ground connection bonding is efficient.

No spark plug

Once the lack of power to the spark plug has been
detected and the led indicates it can be ignited,
follow this procedure:
- Pick-Up check.
Disconnect the control unit connector and check
that the cable between terminal No. 11 (Green)
and terminal No. 9 (Black) is not interrupted.
Check the Pick-Up and its power line:
Electric characteristic
Pick-up resistance value
Pick-up resistance value: 105 ÷ 124 Ohm
If a break in the circuit is found, check again the flywheel and the engine ground connectors (see engine
manual). If non-conforming values are detected, replace the Pick-Up, otherwise check the cable har-
ness and the connections. In case conforming values are measured and the wiring and connections
check is OK, try replacing the control unit (without programming) and make sure the failure has been
solved by checking sparks are produced in the spark plug; only then program the control unit. If no
sparks are produced with the new control unit, proceed as follows.

- HV primary coil check

Disconnect the control unit connector and check
that the cable between terminal No. 17 (Violet) and
terminal No. 9 (Black) is not interrupted (see fig-
ure). If non-conforming values are detected, dis-
connect the two connectors on the HV coil and
check its continuity (see figure). If the values are
correct, repair the cable harness and restore the
connections; otherwise, replace the HV coil.
Electric characteristic
High voltage coil primary resistance value
High voltage coil primary resistance value: 0.4 ÷
0.5 Ohm

HV coil secondary check

Electrical system
ELE SYS - 15