Yamaha YBR 125 electrical system , wiring diagrams and components .

Yamaha YBR 125 for sale on Ebay UKYamaha YBR 125 parts for sale on Ebay UK

Yamaha YBR 125 workshop manuals on Ebay UK

ive studied the internet and many books to find this info , but still i cannot get anywhere near close to the level of information in the Haynes workshop manual , buy one here on Amazon UK .

if you know nothing about electrics like i did not when i first started out , read this book from Amazon UK 
this will save you £100s in repair bills and has easy to follow instructions , and some excellent
tips and advice , literally makes electrical fault diagnosis simple .

Component	Test Parameter	Expected Value
Battery	Resting Voltage (100% Charge)	12.6V – 12.8V
Stator Coil	Resistance (2005-06 / 2007+)	0.6–0.95Ω / 0.45–0.67Ω
Charging System	Regulated Voltage @ 5k RPM	13.7V – 14.7V
Crank Position Sensor	Resistance @ 20°C	248 – 372 ohms
Fuel Level Sender	Full / Empty Resistance	4–10Ω / 90–100Ω

2. Component Location

• Behind Left Cover: Starter Solenoid (brass), Flasher Unit (black), and Headlamp Relay (white).

• Under Seat/Tank: ECU/CDI unit and main wiring harness junctions.

3. Troubleshooting FAQ

• Bike won't crank? Check the 15A main fuse and the brass starter solenoid behind the left cover.

• Fuel gauge acting up? Test the resistance at the sender unit (4-10Ω for Full).

• Intermittent cutting out? Inspect the Crank Position Sensor resistance; heat can often cause these to fail.

Yamaha YBR 125 wiring and electrical post .

battery - 12v 6ah

bulbs
headlight bulb - 35/35w
sidelight bulb - 5w
brake light bulb - 21/5w
plate light bulb - 5w
indicator bulb - 10w
clocks bulbs - 1.7w

15a fuse

Yamaha YBR 125 charging system resistance figures

stator coil - 0.6~0.95(05~06) 2007-on (0.45~0.67)
regulated volts - 13.7~14.7
0.1ma max volt leakage

Yamaha YBR 125 fuel level sender unit resistance figures

full - 4~10 ohms
empty - 90~100 ohms

injection system resistance figures

crank position sensor  - 248 ~ 372 ohms @ 20 degrees C
engine temp sensor - @ 20 degree C~2.5-2.8 ohms - @ 100 degrees C~210-221 ohms
fast idle solenoid - 31.5~38.5 : 25 degrees C
intake air pressure sensor  output voltage - 3.75~4.25V
intake air temp sensor resistance - 2007-2009 2.4 to 2.9 k-ohms 2010 on 5.7 to 6.3 k-ohms
throttle position sensor input voltage 5v  output throttle closed 0.63-0.73v
tip over sensor voltage output - upright 0.4-1.4 ~ 65degree angle 3.7-4.4v


other electrical posts

Yamaha YBR 125 Generator , Alternator Stator  testing 

Yamaha YBR 125 Change Rear Light / Brake Bulb

Yamaha YBR 125 Fuel pump repair

Yamaha YBR 125 Crank Position sensor testing

Yamaha YBR 125 Throttle position / intake air temp and pressure sensors

Yamaha YBR 125 Fast idle solenoid valve testing

Yamaha YBR 125 Injector testing

Yamaha YBR 125 Battery check - charging circuit check

Yamaha YBR 125 blog , testing for no spark .

Yamaha YBR 125 Spark plug , type , gap , torque figures and how to read .

Yamaha YBR 125 flat battery , not charging , overcharging .

Yamaha YBR 125 Kokusan Denki motorcycle Electrical component descriptions

Yamaha YBR 125 fuel injection pump removal / refitting ( how to fit )

Yamaha YBR 125 , Yamaha FI diagnostics Tool Scanner Machine

Yamaha YBR 125 Fuel Injection System , FI diagnostics .

Yamaha YBR 125 Diagnostic Fault codes

Yamaha YBR 125 electronic ignition system

Yamaha YBR 125 Not sparking no spark diagnostics

yamaha ybr 125  wiring diagram

yamaha ybr 125 2007 wiring diagram 

see this diagram larger here

and see below key to above diagram larger here

some photos off my latest Yamaha YBR 125 - ill update soon with id of parts and wires .

regulator 

cdi unit 3d900 

On the left hand side under battery cover you have the solonoid ( brass ) with fuse , if you have a failure to turn bike over it could be this , flasher unit ( black ) , and headlamp relay ( white )

                                   front headlamp loom

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Test battery at the negative and positive terminals 

If you have a voltage meter you can do some basic tests.

When the engine has been off for at least 1-2 hours with ignition key turned off,
100% Charged 12.60 to 12.8v
75% Charged 12.4v
50% Charged 12.1v
25% Charged 11.9v
0% Charged less than 11.8v

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thats about it for interesting electrical tools i own , got any recommendations send a comment below .