Yamaha UMAX, Service Manual

Page: 260 / 320

ELECTRICAL COMPONENTS (YUM1A/YUM2A)
8-55
Out of specification
→
Perform the ignition
system troubleshooting, starting with step 5.
Refer to “TROUBLESHOOTING” on page
8-3.
TIP
If the ignition spark gap is within specification,
the ignition system circuit is operating normally.
a. Disconnect the spark plug cap from the
spark plug.
b. Connect the ignition checker “1” as
shown.
c. Measure the ignition spark gap “a”.
d. Crank the engine by depressing the accel
pedal and gradually increase the spark
gap until a misfire occurs.
CHECKING THE CRANKSHAFT POSITION
SENSOR
1. Disconnect:
• Crankshaft position sensor coupler
(from the wire harness)
2. Check:
• Crankshaft position sensor resistance
Out of specification
→
Replace the crank-
shaft position sensor.
a. Connect the digital circuit tester to the
crankshaft position sensor coupler as
shown.
b. Measure the crankshaft position sensor
resistance.
CHECKING THE STARTER GENERATOR
OPERATION
1. Check:
• Starter generator operation
Does not operate
→
Perform the electric
starting system troubleshooting, starting with
step 4.
Refer to “TROUBLESHOOTING” on page
8-7.
a. Connect the positive battery terminal “1”
and starter generator lead “2” with a jump-
er lead “3”.
WARNING
• A wire that is used as a jumper lead must
have at least the same capacity of the bat-
tery lead, otherwise the jumper lead may
burn.
• This check is likely to produce sparks,
therefore, make sure no flammable gas or
fluid is in the vicinity.
Minimum ignition spark gap
6.0 mm (0.24 in)
Ignition checker
90890-06754
Oppama pet–4000 spark checker
YM-34487
2. Spark plug cap
Crankshaft position sensor resis-
tance
152–228
Ω
2
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with ta-
chometer
YU-A1927
• Positive tester probe
→
black/white “1”
• Negative tester probe
→
white/red “2”
B / W W / R
1 2