Yamaha YZF-R125 ECU Pin-Out Guide: 5D7 Wiring & Color Codes

R125 technical manual https://sites.google.com/view/yamahayzf-r125ultimatebible/r125-technical-data

Yamaha YZF R125 computer pin out. 

Gemini said

Safety First: Always disconnect the battery before working on your ECU to prevent electrical shorts or permanent damage to the bike's computer.

This is my own numbering and not what is on the connector or in any books etc. 1 to 21

                  Number left to right in below table 

Based on the detailed ECU pin-out information for the Yamaha YZF-R125 (specifically for the 5D7 model), here is the breakdown of the wiring and pin assignments.

ECU Pin-Out & Wire Color Guide

The following pin-out covers the standard Yamaha 125cc fuel-injected systems (V2/5D7 models) commonly discussed in maintenance blogs.

Pin #	Wire Color	Function
7	Green	K-Line (Yamaha Diagnostic Tool Connector)
9	Black/White	Ground (Mass)
10	Brown	+12V Switched Power (Active when Ignition is ON)
11	Red/White	+12V Permanent Power (Standby battery current)
12	Brown/Red	+12V Power
13	Orange	Ignition Coil (Mass signal/Trigger)
14	Black/Yellow	Main Light Ground
18	Brown/White	IAT Sensor (Intake Air Temperature)
19	Pink/White	MAP Sensor (Manifold Absolute Pressure)
20	Yellow	TPS (Throttle Position Sensor)
21	Black/Blue	Sensor Ground (SGND)
23	Red	CKP Sensor (Crank Position / Pulser)
24	White	Speed Sensor Signal
29	Light Green/Black	Speedometer Output
31	Yellow/Green	BAS / Tilt Sensor (Bank Angle Sensor)
32	Grey/Red	O2 Sensor
33	Green/Red	ECT Sensor (Engine Coolant Temperature)
35-37	Blue	+5V Reference (Power for TPS/MAP/ECT sensors)

R125 technical manual https://sites.google.com/view/yamahayzf-r125ultimatebible/r125-technical-data