Ignition System Troubleshooting; No Spark At Spark Plugs - Honda GL1800 Service Manual

IGNITION SYSTEM
TROUBLESHOOTING
• Inspect the following before diagnosing the system.
– Faulty spark plug.
– Loose spark plug cap or spark plug wire connections.
– Water in the spark plug cap (Leaking the ignition coil secondary voltage).
• If there is no spark at any cylinder, temporarily exchange the ignition coil with a known-good one and perform the spark
test. If there is spark, the exchanged ignition coil is faulty.

No spark at spark plugs

UNUSUAL CONDITION
Ignition coil No peak voltage
signal voltage
Peak voltage is
normal, but no
spark.
Ignition pulse Low peak voltage
generator
No peak voltage
18-4
PROBABLE CAUSE (check in numerical order)
1. The multimeter impedance is too low; below 10 MΩ/DCV.
2. Cranking speed is too low (battery is undercharged).
3. The sampling timing of the tester and measured pulse were not syn-
chronized. (System is normal if the measured voltage is over the stan-
dard voltage at least once.)
4. Faulty side stand switch or gear position (neutral) switch.
5. An open circuit or loose connection in No. 4 related circuit wires.
– Side stand switch line: Green/white wire
– Neutral switch line: Blue/red and Light green/red wires
6. Open or short circuit in the ignition coil signal wire (No. 1 & 2: Yellow/
white, No. 3 & 4: Yellow/blue, No. 5 & 6: Yellow/red).
7. Faulty peak voltage adaptor.
8. Faulty engine control module (ECM) (when No. 1 through 7 are
normal).
1. Open circuit in ignition coil power input or ground line (page 18-5).
2. Ignition coil is leaking secondary current amperage.
3. Faulty spark plug wire
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 syn-
chronized. (System is normal if the measured voltage is over the stan-
dard voltage at least once.)
4. Faulty ignition pulse generator (when causes No. 1 through 3 are
normal).
1. Faulty peak voltage adaptor.
2. Faulty ignition pulse generator.