Ignition Circuit; No Spark Plug - APRILIA SR MAX 125 ie Service Station Manual

SR MAX 125 ie

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 the resistance value between terminal No. 13 (Red)
and terminal No. 15 (White). Check the Pick-Up and its power line:
Electric characteristic
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 measured, replace the Pick-Up; otherwise, repair the cable har-
ness.
In case conforming values are measured, 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.
Electrical system
ELE SYS - 69