Honda SH300 2006 Manual page 434

IGNITION SYSTEM
TROUBLESHOOTING
• Inspect the following before diagnosing the system.
– Faulty spark plug
– Loose spark plug cap or spark plug wire connection
– Water got into the spark plug cap (leaking the ignition coil secondary voltage)
• "Initial voltage" of the ignition primary coil is the battery voltage with the ignition switch turned to ON (The engine is not
cranked by the starter motor).
NO SPARK AT PLUG
Unusual condition
Ignition coil No initial voltage with ignition
primary volt- switch turned to ON (Other electri-
age cal components are normal)
Initial voltage is normal, but it drops
down to 2 – 4 V while cranking the
engine.
Initial voltage is normal, but no peak
voltage while cranking the engine.
Initial voltage is normal, but peak
voltage is lower than standard
value.
Initial and peak voltage are normal,
but no spark jumps at plug.
Crankshaft Peak voltage low
position
(CKP) sensor
No peak voltage.
20-4
Probable cause (Check in numerical order)
1. An open circuit in Black/White wire between the igni-
tion coil and engine stop relay.
2. An open circuit or loose connection in engine stop
relay related circuit or faulty engine stop relay.
3. Loose or poor contact of the ignition coil primary wire
terminal, or an open circuit in primary coil.
4. Faulty ECM (when the initial voltage is normal with the
ECM connector disconnected).
1. Incorrect peak voltage adaptor connections.
2. Cranking speed is too slow. (Battery is undercharged.)
3. No voltage between the Black/White (+) and body
ground (–) at the ECM connector or loosen ECM con-
nector.
4. An open circuit or loose connection in Green/White
wire of the ECM.
5. An open circuit or loose connection in Yellow/Blue
wire between the ignition coil and ECM.
6. Short circuit in the ignition primary coil.
7. Faulty sidestand switch.
8. Loose or poor connection or an open circuit in side-
stand switch White/Green wire.
9. Faulty CKP sensor (measure the peak voltage).
10.Faulty ECM (when above No.1 – 9 are normal).
1. Incorrect peak voltage adaptor connections.
2. Faulty peak voltage adaptor.
3. Faulty ECM (when above No.1 and 2 are normal).
1. The multimeter impedance is too low; below 10 MΩ/
DCV.
2. Cranking speed is too slow. (Battery is undercharged.)
3. The sample timing of the tester and measured pulse
were not synchronized. (System is normal if measured
voltage is over the standard voltage at least once.)
4. Faulty ignition coil.
5. Faulty ECM (when above No.1 – 4 are normal).
1. Faulty spark plug or leaking ignition coil secondary
current ampere.
2. Faulty ignition coil.
1. The multimeter impedance is too low; below 10 MΩ/
DCV.
2. Cranking speed is too slow. (Battery is undercharged.)
3. The sampling timing of the tester and measured pulse
were not synchronized. (System is normal if measured
voltage is over the standard voltage at least once.)
4. Faulty CKP sensor (when above No. 1 – 3 are normal).
1. Faulty peak voltage adaptor.
2. Faulty CKP sensor.