Yamaha YZF-R125 Service Manual: Checking the horn
1. Check:
Horn resistance
Out of specification 
Replace.
a. Disconnect the horn connectors from the horn terminals.
b. Connect the pocket tester ( × 1) to the horn
terminals.
- Positive tester probe
horn terminal "1" - Negative tester probe
horn terminal "2"
c. Measure the horn resistance.
2. Check:
Horn sound
Faulty sound Adjust or replace.
a. Connect a battery (12 V) to the horn.
b. Turn the adjusting screw in direction "a" or "b" until the specified horn sound is obtained.
Checking the rectifier/regulator
1. Check:
Rectifier/regulator output voltage
Out of specification → Replace the
rectifier/
regulator.
a. Set the engine tachometer to the spark plug
lead.
b. Connect the pocket tester ...
Checking the fuel sender
1. Drain the fuel from the fuel tank.
2. Check:
Fuel sender resistance
Out of specification → Replace the fuel
sender.
a. Connect the pocket tester ( ×
10) to the fuel
sender c ...
Other materials:
Troubleshooting method
The engine operation is not normal and the
engine trouble warning light comes on.
1. Check:
Fault code number
a. Check the fault code number displayed on
the FI diagnostic tool.
b. Identify the faulty system with the fault code.
Refer to "Self-Diagnostic Function table".
c. Identi ...
Indicator and warning lights
Indicator and warning lights
Neutral indicator light""
Turn signal indicator light""
High beam indicator light""
Engine trouble warning light""
Coolant temperature warning light""
Turn signal indicator light""
This indicator light flashes when the
turn signal switch is pushed t ...
Installing the swingarm
1. Lubricate:
Bearings
Spacers
Dust covers
Pivot shaft
2. Install:
Bearings "1"
2. Swingarm
A. Left side
B. Right side
3. Install:
Swingarm adjusting collar "1"
Swingarm "2"
Pivot shaft
Pivot shaft nut "3"
a. Install, and then fully turn in the swingarm adju ...