How To Read A Wiring Diagram Part 1:

Wiring Diagrams Break Down The Electrical System Into Individual Components:

The Basics For Better Wiring Diagram Understanding

Wire Colors: English VS German

• TR – Transparent
• WS – White / Weib
• VI – Purple / Violet
• BL – Blue / Blau
• BR – Brown / Braun
• GE – Yellow / Gelb
• GR – Gray / Grau
• GN – Green / Grun
• OR – Orange / Orange
• RS – Pink / Rosa
• RT – Red / Rot
• SW – Black / Scharz

We can see a lot of good information in the above wiring diagram. The power supply is on the top of the diagram from fuse 60 with a RT/SW Red / Black wire which feeds power to pin 9 of the control unit General Module. The ground circuit is on the bottom of the diagram at X849 and X490 which is a BR or Brown wire. You can also see wire gauge size such as .75 on ground X849. You can also see some numbers at the power side such as (30) at the fuse. And 31L at the ground for X849. Let me explain what these numbers mean:

Important Terminal Terminology

• B+ Battery Positive (Red)
• B- Battery Negative (Black)

• KL = Key Position

Power Supply Terminology

• KL_0 = Ignition Off
• KL_R = Voltage with key in accessory position
• KL_15 = Voltage with key in run (Ignition on – Includes Accessory)
• KL_30 = 12 Volts at all times
• KL_30g = 12 Volts with a time disconnect
• KL_30gf = 12 Volts with a fault disconnection
• KL_30H = Starter Signal

Ground / Earth Terminology

• KL_31 = Ground
• KL_31E = Electronic Ground
• KL_31L = Load Ground (Working Side)
• KL_50 = Voltage in Start Position
• KL_58 = Interior Light Dimmer Signal

Now using this information review the wiring diagram and it make a lot more sense!

This is a good place to start. You can now check power and ground and read the terminal status. As well as understand the color coding symbols so you can find the correct wire when looking at the vehicle.

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