Unfortunately, there are quite a number of standards and manufacturer conventions regarding the color coding of cables and connectors. In this chapter, we make a determination from a CTC perspective for cables that you will find on CTC modules and in modules modified by us.

Note: We adhere to these color rules from July 2021. Unfortunately, we only thought about cable colors too late, which means that for everything delivered by us before July 2021, you cannot rely on the cable colors following a system!

From our perspective, the following assignment is generally expected:

  • Negative pole: black or blue
  • Positive pole: red

Therefore, we decided against using blue for the positive pole in the locomotive. You can find other color standards here:

In the following, we understand “marking” to mean the color of a connector or a shrink sleeve at the end of the cable.

Single Cables

Locomotive Installation

Cable Color Marking Description Polarization Standard
brown brown - Track left / both tracks undefined or ground Märklin
red red - Track right / middle rail undefined or phase NEM 658, Märklin
black black - CTC module or decoder negative pole negative (GND) -
orange orange - CTC module or decoder positive pole positive (VBB) Märklin
green green - Motor left changing Märklin
green green white white AUX high-side switched positive (VBB) -
grey grey - Motor right changing NEM 658
grey grey white white Light front high-side switched positive (VBB) -
grey grey yellow yellow Light rear high-side switched positive (VBB) -
purple purple - AUX low-side switched negative (GND) AUX 2: NEM 658
white white - Light front low-side switched negative (GND) NEM 658
yellow yellow - Light rear low-side switched negative (GND) NEM 658, Märklin

Model Railway Layout

Turnout modules, IO-boards, signals, …

Cable Color Marking Description Polarization Standard
brown brown - Track left / both tracks undefined or ground Märklin
red red - Track right / middle rail undefined or phase NEM 658, Märklin
green green - Turnout with polarity change or motorized: drive left changing Märklin
grey grey - Turnout with polarity change or motorized: drive right changing NEM 658
black black - Turnout/light: negative pole negative (GND)  
yellow yellow - Turnout/light: power supply / positive pole positive (VBB) Märklin
blue blue green green Turnout: ground drive position straight switched negative (GND) Märklin
blue blue green green Semaphore signal: ground drive position green switched negative (GND) Märklin
blue blue red red Turnout: ground drive position turning switched negative (GND) Märklin
blue blue red red Semaphore signal: ground drive position red switched negative (GND) Märklin
white white - Signal line or LED Processor positive (3.3V)  

Multi-conductor Cables

IR Balise

At the turnout module, 4-conductor cable (white, brown, green, yellow) with socket strip at 2.54mm pitch. At the IR balise (track) 2-conductor cable with pin strip at 2.54mm pitch.

Cable Color Marking Description Polarization Standard
brown (IR-1) / green (IR-2) green green IR balise: negative pole (TX-GND) TX signal -
white (IR-1) / yellow (IR-2) red red IR balise: positive pole (PWM-VCC) PWM signal -

IR Receiver in Locomotive

3-conductor cable with angled 8-pin header at 1.27 mm pitch.

Cable Color Marking Description Polarization Standard
black black red red IR receiver: negative pole (GND) negative (GND) -
red red - IR receiver: positive pole (VCC, 3.3V) positive 3.3V (VCC) -
purple purple - IR receiver: TXD Serial data -

NFC Reader

Wires soldered to NFC reader.

Cable Color Marking Description Polarization Standard
black black - NFC reader: negative pole (GND) negative (GND) -
red red - NFC reader: positive pole (VCC, 3.3V) positive 3.3V (VCC) -
green green - NFC reader: TXD Serial data -
blue blue - NFC reader: RXC Serial data -


Notes:

  • Please contact us if you have any uncertainties - it is usually cheaper than repairing.
  • We gladly accept additions that you think are missing.

Here are some links that we have looked at and based our colors on.

Standards:

Märklin-Collector-Infos.de (Peter Roland):

The Moba (Wiki):