2005 YAMAHA VX110 engine

7-10
E
–+ELECELECTRICAL ANALYSIS
Low resistance measurement
NOTE:
When measuring a resistance of 10 Ω
or less
using a digital tester, the correct measure-
ment cannot be obtained because of the
tester’s internal resistance.
To obtain the correct value, subtract the
internal resistance from the displayed mea-
surement.
The internal resistance of the tester can be
obtained by connecting both of its terminals.
Correct value =
Displayed measurement –
Internal resistance
Peak voltage measurement
NOTE:
When checking the condition of the ignition
system it is vital to know the peak voltage.
Cranking speed is dependant on many fac-
tors (e.g., fouled or weak spark plugs, a
weak battery). If one of these is defective,
the peak voltage will be lower than specifica-
tion.
If the peak voltage measurement is not
within specification the engine will not oper-
ate properly.
A low peak voltage will also cause compo-
nents to prematurely wear.
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7-11
E
–+ELECELECTRICAL ANALYSIS
Peak voltage adapter
NOTE:
Throughout this chapter the part numbers of
the specified peak voltage adapters have
been omitted. Refer to the following part
numbers.
The peak voltage adapter should be used
with a digital tester.
When measuring the peak voltage, connect
the peak voltage adapter to the digital circuit
tester and switch the selector to the DC volt-
age mode.
NOTE:
Make sure that the adapter leads are prop-
erly installed in the digital circuit tester.
Make sure that the positive pin (the “+” mark
facing up as shown) on the adapter is
installed into the positive terminal of the
tester.
The test harness is needed for the following
tests.
È Voltage measurement
É Peak voltage measurement
Test harness
NOTE:
If the lighting coil and pickup coil(s) are mea-
sured unloaded, disconnect the test harness
on the output side coupler.
Peak voltage adapter:
YU-39991
Peak voltage adapter B:
90890-03172
Checking steps:
Disconnect the coupler connections.
Connect the test harness between the
couplers.
Connect the tester terminals to the termi-
nals which are being checked.
Run the engine and observe the mea-
surement.È
É
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7-12
E
–+ELECIGNITION SYSTEM
IGNITION SYSTEM
WIRING DIAGRAM
10A
10A
3A
30A20A
WBrBRFREE
PUSHBWFREE
PUSH
Br BrFREE
PUSH
BW
W
BrBrBrBrR
W
B/W
B/O
B/O
B/O
B/R
P/R
P/R
W/B
P/W
P/W
B/O
L/B
B/WB/R
B/OP/W
P/R
W
W
WLR
Y
G
O
O
W
GG
BW
GG
O
OLG
W
Y
W
G/O
W/BR/Y
Y/G
BL
PBWP/W
B/GB/Y
Y/WL/RB/RB/W
B
B
BBP
P
P
BBP
RR
BBR
R/Y
B/OL/BB/OL/B
B/G
G/OB/OG/O
P/W
B/OB/YB/YR/Y
R/Y
R/Y
R/YB/YR/Y
R/Y
B/O
B/RR/Y
R/Y
R/YY/W
Y/GL/R
Y
P
P
O
O R
R
R
BB
BrRB/O
BBr
B/W
Y BrL R B
R
GB
R/YBBr
4
0 98
B
B B
B
H
I JK LM NOQ
PR
3
5
67 2 1
A
A A
A
C
D
E
F
G
1Battery
2Fuse (30 A)
3Fuse (20 A)
4Fuse (3 A)
5Fuse (10 A)
6Fuse (10 A)
7Starter relay
8Main and fuel pump
relay9Electronic control
throttle valve relay
0Slant detection switch
AIgnition coil
BSpark plug
CCam position sensor
DEngine temperature
sensor
EThermoswitch
(engine)FThermoswitch
(exhaust)
GOil pressure switch
HRemote control unit
(Deluxe model only)
IAntenna
(Deluxe model only)
JECM
KRectifier/regulatorLThrottle body assem-
bly
MAccelerator position
sensor
NPickup coil
OLighting coil
PStart switch
QEngine stop switch
REngine shut-off switch
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7-14
E
–+ELECIGNITION SYSTEM
IGNITION SPARK
WARNING
When checking the spark gap, do not
touch any of the connections of the spark
checker/ignition tester lead wires.
When performing the spark gap test, take
special care not to let sparks leak out of
the removed spark plug cap.
When performing the spark gap check,
keep flammable gas or liquids away,
since this test can produce sparks.
1. Check:
Ignition spark
Weak →
Check the ECM output peak
voltage.
Check the ignition coil for resistance.
Checking steps:
Connect the spark plug cap to the special
service tool.
Spark checker:
YM-34487
Ignition tester:
90890-06754
Crank the engine and observe the igni-
tion system spark through the discharge
window.
OK
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7-15
E
–+ELECIGNITION SYSTEM
IGNITION SYSTEM PEAK VOLTAGE
WARNING
When checking the electrical components,
do not touch any of the connections of the
digital tester lead wires.
NOTE:
If there is no spark, or the spark is weak,
continue with the ignition system test.
If a good spark is obtained, the problem is
not with the ignition system, but possibly with
the spark plug(s) or another component.
1. Measure:
ECM output peak voltage
Below specification →
Measure the
pickup coil output peak voltage.
NOTE:
When measuring the ECM output peak volt-
age while cranking the engine, disconnect
the ignition coil couplers for all cylinders
except for the cylinder being measured.
To crank the engine, connect the engine
shut-off cord (lanyard) to the engine shut-off
switch, and then press the start switch.
Test harness (2 pins):
New: YB-06867
Current: YB-06767
Test harness FWY-2 (2 pins):
New: 90890-06867
Current: 90890-06767
ECM output peak voltage:
Black/red (B/R) –
Red/yellow (R/Y)
Black/white (B/W) –
Red/yellow (R/Y)
Black/yellow (B/Y) –
Red/yellow (R/Y)
Black/green (B/G) –
Red/yellow (R/Y)
r/minLoaded
Cranking 2,000 3,500
V 90 130 140
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7-16
E
–+ELECIGNITION SYSTEM
2. Measure:
Pickup coil output peak voltage
Below specification →
Replace the
pickup coil.
Above specification →
Replace the
ECM.
NOTE:
To crank the engine, connect the engine shut-
off cord (lanyard) to the engine shut-off switch,
and then press the start switch and engine
stop switch simultaneously.
Test harness (3 pins):
New: YB-06877
Current: YB-06777
Test harness HM090-3 (3 pins):
New: 90890-06877
Current: 90890-06777
Pickup coil output peak voltage:
White/black (W/B) –
Black/orange (B/O)
r/minUnloaded Loaded
Cranking 2,000 3,500
V 8.0 6.9 19.4 25.1
3. Measure:
Lighting coil output peak voltage
Below specification →
Replace the light-
ing coil.
Test harness (3 pins):
New: YB-06870
Current: YB-06770
Test harness SMT250-3 (3 pins):
New: 90890-06870
Current: 90890-06770
Lighting coil output peak voltage:
Green (G) – Green (G)
r/minUnloaded
Cranking 2,000 3,500
V 7.8 24.5 41.6
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7-17
E
–+ELEC
NOTE:
To crank the engine, connect the engine shut-
off cord (lanyard) to the engine shut-off switch,
and then press the start switch and engine
stop switch simultaneously.
4. Measure:
Rectifier/regulator output voltage
Below specification →
Replace the recti-
fier/regulator.
NOTE:
Do not use the peak voltage adapter to mea-
sure the output voltage.
Disconnect the output lead of the tester har-
ness.
Test harness (6 pins):
YB-06848
Test harness FSW-6A (6 pins):
90890-06848
Rectifier/regulator output
voltage:
Red (R) – Black (B)
r/minUnloaded
3,500
V 13.0
BATTERY
Refer to “ELECTRICAL” in Chapter 3.
FUSE
Refer to “STARTING SYSTEM”.
SPARK PLUGS
Refer to “POWER UNIT” in Chapter 3.
IGNITION SYSTEM
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7-18
E
–+ELEC
IGNITION COIL
1. Measure:
Primary coil resistance
Out of specification →
Replace.
NOTE:
When measuring a resistance of 10 Ω
or less
using a digital tester, the correct measurement
cannot be obtained because of the tester’s
internal resistance.
Refer to “Low resistance measurement”.
Primary coil resistance:
1.19–1.61
Ω at 20 °C (68 °F)
2. Measure:
Secondary coil resistance
Out of specification →
Replace.
Secondary coil resistance:
8.5–11.5 k
Ω at 20 °C (68 °F)
ENGINE STOP SWITCH
1. Check:
Engine stop switch continuity
Out of specification →
Replace.
Engine stop switch continuity
(black coupler)
Clip PositionLead color
White Black
InstalledFree
Push
RemovedFree
Push
IGNITION SYSTEM
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