Diesel Laptops CAT 40 Pin ECM Bypass Breakout Cable


This cable is used on “older” CAT engines, which includes the 3406E, C-10, C-12, and more.

SKU: BYPASS-CAT-40-PIN Categories: ,


Some sample engine serial numbers (ESN) that this CAT cable harness would include CAT 3406E, C-10, & C-12 with ESN: 8YS, 9NS, 5DS, 1LW, 2PN, 1YN, 5EK, or 6TS.

If your engine serial number is not listed, please call or email us so we can verify for you. If you look at your ECM, and it has 40-pins, this cable will work.

 Our CAT cables can be used for a variety of purposes, including:

  • Most OEMs recommend NOT programming the vehicle through the dash connector, but instead go direct to the ECM. These are the perfect programming cables for such a project.
  • If you are having issues with the diagnostic port on your commercial truck and wish to bypass the vehicle wiring and go direct to the ECM.
  • If you have an ECM that is not installed on the truck and wish to do programming or modifications to it on the workbench.


  • Harness length is 10″.
  • All cables are tested on live ECMs and validated before shipping.
  • Professional, quality manufacturing of cables made in the USA.
  • 12-month warranty on all components


NOTE: This cable will not work by itself. You will need part number BYPASS-MAIN for this cable to function properly. Our unique design allows you to purchase this main cable first, then purchase the “ends” that you need to connect to various ECMs

Additional information

Weight5 lbs


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