Yamaha YZF-R125 Service Manual: Checking the relays
Check each switch for continuity with the pocket
tester. If the continuity reading is incorrect, replace
the relay. 
1. Disconnect the relay from the wire harness.
2. Connect the pocket tester ( × 1) and battery (12 V) to the relay terminal as shown.
Check the relay operation.
Out of specification → Replace.
Starter relay
1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe
Starting circuit cut-off relay
1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe 
Headlight relay
1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe 
Radiator fan motor relay
1. Positive battery terminal
2. Negative battery terminal
3. Positive tester probe
4. Negative tester probe
Checking and charging the battery
WARNINGBatteries generate explosive hydrogen gas
and contain electrolyte which is made of poisonous
and highly caustic sulfuric acid.
Therefore, always follow these preventive
mea ...
Checking the turn signal relay
1. Check:
Turn signal relay input voltage
Out of specification →The wiring circuit
from
the main switch to the turn signal relay coupler
is faulty and must be repaired.
a. Connect the poc ...
Other materials:
Checking the camshaft sprocket and timing chain guide
1. Check:
Camshaft sprocket
More than 1/4 tooth wear "a" Replace
the
camshaft sprocket, timing chain and crankshaft
as a set.
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
2. Check:
Timing chain guide (exhaust side)
Damage/wear Replace.
...
Handlebar switches
Left
Left
1. Pass switch "PASS"
2. Dimmer switch "/"
3. Turn signal switch "/"
4. Horn switch""
Right
Right
Engine stop switch "/"
Start switch""
Pass switch "PASS"
Press this switch to flash the headlight.
Dimmer switch "/"
Set this switch to""
for the high
beam an ...
Important manual information
Particularly important information is distinguished in this manual by the
following notations:
This is the safety alert symbol. It is used to alert you to potential personal
injury
hazards. Obey all safety messages that follow this symbol to avoid possible
injury
or death.
WARNING
...