1987-2003 Yamaha YFZ350 Banshee supplementary service manual, Page 239Get this manual
3Lighting voltage test Connect the Pocket Tester (YU-03112)to the headlight leads (Black (1), Yellow (5) and Green (3))Turn the "LIGHTS" (Dimmer) switch to "LO" or "HI" positionStart the engine and accelerate to specific engine revolutionMeasure the lighting voltage MORE THAN 16.3V AT 8,000 rlmin
Voltage regulator is faultyReplace it
LESS THAN 11.5V AT 2,500 rimin
4Lighting coil resistance test Disconnect the CDI magneto leads (Yel1 low) and Black (2)) from the wireharnessConnect the pocket tester (YU-03112) to the CDI magneto leadsMeasure the lighting coil resistanceLighting Coil Resistance (Yellow (DBlack (2)): 0.28-0.380 at 20 (68OF)