DSS connector plug for Freightliner chassis (XCM)

Credits: The following content was provided by NMBluept

Disclaimer: please use at your own risk, practice due diligence and verify that the information provided applies to and is compatible with your specific equipment and double check your work.


DSS connector plug for Freightliner chassis (XCM)

Note for DSS builders: the DT-4 connector used in the instructions for the DSS is not compatible with Freightliner chassis (at least with the XCM chassis). If your DEF Header connector looks like this picture, you will need to obtain/make a different plug.


Parts list for the FL pig tail:

Note all parts except the cable are TE Connectivity part #’s

  • Plug: 1-1703818-1
  • Connector Cover: 965786-1
  • Terminal pins (PCB Connector Contact, Male, Tin): 1-963745-1
  • Cable: Copper Wire, Electric Conductor 4, Core 20 AWG

As with many of these type items it is difficult to purchase them in small quantities, most suppliers of these things sell in quantities of 100 or more. I did find that www.ttiinc.com has all the parts available in reasonable quantities:

  • plug min qty = 3
  • cover min qty = 8
  • terminal pins min qty = 10.
  • I found 5 M of 20 AWG 4-conductor cable on Amazon

[Editor Note: corrected plug part number.]

[Editor Note: Some or all of the above parts may be available from digikey in single item quantities.]

[Editior Note: to build this connector/cable assembly you will need to crimp the terminal pins to the wires in the cable. Most likely you will not have the appropriate crimp tool, however it can be done by soldering, or carefully with pliers. Having extra pins on hand is beneficial if you have never done this before.]

Pin assignments for the AMP plug:

Pin 1 = CAN-L
Pin 2 = CAN-H
Pin 3 = +12v
Pin 4 = ground


Verify the connections:

Before connecting the cable to the DB9 [or other CAN board connector] verify the proper plug wiring by plugging the connector into the chassis wiring harness and measuring voltages with ignition key in ACC (except ground):

  • Pin 1 CAN-l ~2.38v measure to ground
  • Pin 2 CAN-H ~2.52v measure to ground
  • Pin 3 +12V measure to ground >12v
  • Pin 4 ground (verify with ohm meter, ignition off, to a solid metal ground = 0 ohms)

Note: this will create the codes associated with a DEF Header failure, but they can be cleared with a Scan Gauge or similar code scanning device.



  • 20 awg wire is easy to work with and easily fits the DB9 [or CAN board] screw terminals.
  • To disconnect the connector pull out on the square yellow piece (gently pry it up if needed) until it “pops” out. The connector will then come apart easily.
  • When inserting the terminal pins into the plug, if they won’t seat there is a locking mechanism that must be released by lifting up the yellow plastic part near the plug end. It will only move up ~1mm. Look into the wire end to see the yellow locks. Once the terminal pins are pushed in use needle nose pliers to pull them further and engage the locking tabs on the terminal pins.
  • Double check your wire colors to pins in order get the wires in the proper locations on the DB9 screw terminals.

15 Comments to DSS connector plug for Freightliner chassis (XCM)

  1. […] NMBluept – Freightliner connector info […]

  2. […] DT-4 Extension Cable – from Diode Dynamics $15 + shipping Note this connector style will not be correct for all applications: – Freightliner owners please see this page. […]

  3. Bmiller says:

    I got my connector, pins and seal plugs from Mouser Electronics and you can buy a minimum of 1 plug. I used part numbers 4-1703818-1 Plug, sames listed above only the plug is Blue, Terminal pins 1-963745-1 and Wire Seals 828904-1. I had been discussing this with Archer2 in another area.

    • Bmiller says:

      Forgot to mention, I am dealing with a Freightliner Custom Chassis S2RV chassis.

    • Archer2 says:

      Bill, you say that you got the connector part number 4-1703818-1 Plug? I hope I didn’t tell you to do that. It’s true that the insert is blue but that is not cosmetic. These connectors come in 4 varieties and colors and the first digit in the part number (1,2,3 or 4) is how they are differentiated. Each color/variety has a molded-in “key” in a different place so they will only mate with the receptacle part number that starts with the same number.
      So, in short, the blue connector will not work. You need the black version part number
      1-1703818-1 Plug. I am truly sorry if I gave you the wrong info.

    • Bmiller says:

      I want to correct my post about the Plug the plug I ordered does not quite fit, it has an index pin in the wrong location. I was able to trim the one pin and it fits but THE CORRECT PLUG IS 1-1703818-1

      Sorry for the confusion. Everything else I ordered has worked and I will test tomorrow.

      • RickyC says:

        Just checking to see if we were successful. I to have the same chassis . The hardest thing for me is finding the connection on the DEF head. The space is very limited as you know. Is there anyway you could share a picture of the connection? If you can that would be great. Thanks

        • Archer2 says:

          Go to this link. https://defsim.myervin.com/dss-connector-plug-for-freightliner-chassis-xcm Even though it says it’s for Freightliner XCM, it is also for other Freightlinermchassis. Scroll down and you should see several pictures along with the instructions for wiring. I’m sorry I don’t have any pictures that show where it is on your particular coach. All I can suggest is to track the cable from where it exits the OEM sensor until you come to the connector. The connector is usually less than 2 feet from the top of the OEM sensor and the connector is about 3 inches long, 1 1/2 inches square and is black with a bright yellow latch mechanism on the top. If the cables and hoses coming from the sensor are all zip-tied together you may have to cut the zip-tie(s) to be able to gain enough slack in the cables to see the connector. Good luck

  4. Joe Zinkel says:

    I have assembled the connector for my XCM chassis, Just wanted to clarify for myself. When this is plugged into coach, I will need to be at some repair shop so fault codes can be cleared with scan gauge?
    Also when I was assembling the box, I accidentally bumped reset on board, would this have rest board (program was already loaded)..It was not plugged into anything


    • Archer2 says:

      Hi Joe, congrats on your successful build. First thing, no you will not need to be at a shop. If you mean when you plug the DSS in in place of your OEM DEF sensor to test it, assuming you didn’t have any codes at the time and that you did the swap with the key OFF and that the DSS is wired and working correctly, you shouldn’t get any new codes. After you are satisfied that the DSS worked just turn the key off and swap back to the OEM sensor.
      If you are asking whether you need to be at a shop if you have a failed OEM Sensor and you have the 3 fault codes (SPNs 1761, 3364 and 3031) and you plug the DSS in to avoid deration then also no. The vehicle diagnostics should see that there is no longer a problem and will clear the first 2 immediately then after 3 cycles of running the engine for at least 5 minutes each time the on board diagnostics will clear the 3rd (3031) and the amber Malfunction Indicator Light.
      No shop required except to install a new DEF Sensor when available.

    • Archer2 says:

      Also, I forgot to mention that pushing the “Reset” button will not erase the programming. It works just like killing the power to the board and then plugging it back in. It just stops and restarts the processor.

  5. Joe Zinkel says:

    Thanks for response
    We push off from Wis. to Texas tomorrow morning…Hopefully won’t need it


  6. jon says:

    In the ‘hints’ section above it states “To disconnect the connector pull out on the square yellow piece (gently pry it up if needed) until it “pops” out. The connector will then come apart easily.” Is the referenced square yellow piece the female plug that in the photo shows overspray on the plug? Or is it referring to the yellow piece on “Plug: 1-1703818-1”? I tried to pull off the yellow piece from “Plug: 1-1703818-1” and all I did was break the weak prongs on the side (good thing TTI sold minimum of 5 🙂

    Since I’m still waiting for parts, I have not tried to unplug the DEF sensor plug and so I am confused about it. I have received the “Plug: 1-1703818-1” and part of it has this yellow piece on it. I don’t really understand why that yellow piece is there, is it a locking mechanism for the female? I’d like to better understand this before I get my hands on the actual harness.

    • jon says:

      So…I re-read this section again for the umpteenth time and see that I overlooked the part about locking the pins into place. There is a place to pry up under the middle section of the yellow locking mechanism of the plug. That answers the 2nd part of the above question.

      I’d still like to know more about disconnecting the female from this plug.

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