Unfortunately, there is a whole set of standards and manufacturer conventions regarding the color coding of cables and connectors. In this chapter, we make a CTC-specific determination for cables that you will find on CTC modules and in modules we have converted.

Note: We adhere to these color rules starting from July 2021 . Unfortunately, we did not consider cable colors early enough, meaning that anything delivered by us before July 2021 cannot be relied upon to follow a systematic color scheme From our perspective, the following assignment is generally expected:

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

Therefore, we have decided against using blue for the positive pole in the locomotive, as per NEM standards. Other color standards can be found here:

In the following, "marking" refers to the color of a connector or heat-shrink tubing at the end of the cable.

Individual Cables

Locomotive Installation

Cable Color Marking Description Polarity Standard
brown brown - Track left / both tracks undefined or ground Märklin
red red - Track right / center conductor 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 alternating Märklin \n green green white white AUX high-side positive (VBB) switched - \n gray gray - Motor right alternating NEM 658
gray gray white white Front light high-side positive (VBB) switched -
gray gray yellow yellow Rear light high-side positive (VBB) switched -
violet violet - AUX low-side negative (GND) switched AUX 2: NEM 658
white white - Front light low-side negative (GND) switched NEM 658
yellow yellow - Rear light low-side negative (GND) switched NEM 658, Märklin

Model Railway Layout

Turnout modules, IO boards, signals, ...

Cable Color Marking Description Polarity Standard
brown brown - Track left / both tracks undefined or ground Märklin
red red - Track right / center conductor undefined or phase NEM 658, Märklin
green green - Turnout with polarity reversal or motorized: drive left alternating Märklin \n gray gray - Turnout with polarity reversal or motorized: drive right alternating 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 negative (GND) switched Märklin
blue blue green green Semaphore: ground drive position green negative (GND) switched Märklin
blue blue red red Turnout: ground drive position diverging negative (GND) switched Märklin
blue blue red red Semaphore: ground drive position red negative (GND) switched Märklin
white white - Signal line or LED Processor positive (3.3V) switched

Multi-Core Cables

IR Beacon

4-core cable (white, brown, green, yellow) with socket strip in 2.54mm pitch at the turnout module.

2-core cable with pin strip in 2.54mm pitch at the IR beacon (track).

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

IR Receiver in Locomotive

3-core cable with angled 8-pin strip in 1.27mm pitch.

Cable Color Marking Description Polarity 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

Soldered cables on the NFC reader.

Cable Color Marking Description Polarity 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 in case of uncertainties – this is usually cheaper than repairs.
  • We welcome any additions you feel are missing from your perspective.

Other Links to Cable Colors

Here are some links we have reviewed and used as the basis for our color definitions.

Standards:

Märklin Collector Info (Peter Roland):

Moba (Wiki):