NEM 651 \ Six Pin DCC Plug

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Summary: The NEM 651 or 6 Pin DCC Plug is one of the standard plugs used for Locomotive Interfaces. The plug is integrated into the decoder (or possibly on the end of a loose wiring harness) and mates with a fixed 6 position socket mounted on the locomotive chassis. The 6-pin version is known as the small size and is intended for use in N gauge locomotives.

Decoder fitted with a 6-pin plug

See NEM 652/NMRA 8 Pin DCC Plug for the 8 pin variety

DCC Ready locomotives with 6-pin sockets ship with a factory-installed 6 pin blanking plug that shorts the rail pickups to the motor terminals in the absence of a decoder. This plug must be removed to install the decoder. The blanking plug must be replaced if removing the decoder and returning the locomotive to analog operation.


Pin 1 Orange Motor Right
Pin 2 Grey Motor Left
Pin 3 Red Right Rail
Pin 4 Black Left Rail
Pin 5 White Front Headlight (F0)
Pin 6 Yellow Rear Headlight (F0)

This table depicts the Pin assignment of the NMRA 6-Pin plug or 6-Pin socket. Although the wiring is designed to work properly one way round, no harm is done if it is inserted in reverse by mistake (but it will not work correctly). This plug and socket combination is identical to the NEM 6-Pin plug and socket (defined by NEM 651) used in Europe.

Pin 1 should be clearly marked on the plug and socket with a small triangle or dot.

Note that there is no common positive supply wire for the headlights, the headlights are supplied by rectifying the supply from the rails as shown below. This circuitry will already be present in a DCC-ready locomotive equipped with a 6-Pin socket and headlights.


The 6-pin connector has the following specifications:

  1. 1x6 six pins at 0.05" pitch
  2. 0.5A contact rating (maximum sustained load)
  3. 0.75A peak contact rating

The contact ratings are for the individual pins of the connector only and do not reflect the capabilities of a particular decoder or requirements of a particular locomotive. For example, if a locomotive's maximum sustained motor current is over 0.5A, this plug and socket should not be used.

This information is based on NMRA S- Six & Eight Pin Decoder Interface. See also S-9.1.1 Other Connectors.

NEM Standard: in French.

See Also