Ignition Circuit; No Spark Plug - VESPA GT 125 Workshop Manual

Vespa GT 125-200
~ 7 ÷ 9 Ohm
Diagnostic code - 3 flashes
If the 3-flash code is detected, check if the failure
occurs when the MASTER key in inserted into the
key switch.
- If the failure disappears when the MASTER key
is used, encode the service keys (Blue) again.
- If the failure persists, it means that the MASTER
key and the control unit are not linked; in this case,
replace the control unit and then encode the keys.
The immobilizer system is efficient when, after
switching over to "ON", only a 0.7-second flash is
detected (see diagram).
In this case, the engine can be started.
Example with programmed control unit, trans-
ponder, programmed key and aerial working prop-
erly.
Ignition is enabled (regular conditions of use)

Ignition circuit

Once the immobilizer system is enabled, the HV coil and the signals from the Pick-Up will produce a
spark in the spark plug.
The battery provides the basic power supply. The system is adjusted so that the start-up system im-
mediately detects an eventual battery voltage drop, but this is practically irrelevant for the ignition
system.
The Pick-Up is connected to the control unit by a single cable; then, for the ground circuit, the control
unit is connected to the Pick-Up by the chassis and the engine ground lead.
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. 2 (Green) and
terminal No. 8 (Black) is not interrupted. Check the Pick-Up and its power line:
Electrical system
ELE SYS - 75