2005-2009 Honda TRX400EX/TRX400X Service Manual, Page 298Get this manual
IGNITION SYSTEM
TROUBLESHOOTING
The leM stops the ignition to prevent starting the engine when the transmission is in the reverse position (the reverse switch is turned to ON) with the engine stoppedWhen the vehicle is reverse driving, the leM limits the engine speed to 4,000 rpm (min" ]' Inspect the following before diagnosing the system:Faulty spark plugLoose spark plug cap or spark plug wire connectionWater got into the spark plug cap (leaking the ignit ion coil secondary voltage)
No Spark at Spark Plug
Unusual Condition peak voltageprimary voltage
Probable Cause(Check in numerical order)
No peak voltage