I create my own cable sets for various purposes both at work and at home. I agree that crimping and/or soldering your own cable sets is not the most creative thing in hobby/professional electronics, but if there is nothing even close available in your electronics store... you have no other choice.

This project is about a working prototype that is used in a small local manufacturing facility during a rewiring of a few hundreds of OBD extension cables. You might ask, why would anyone manufacture and then rewire the OBD cables in the first place – there are tens or hundreds types available everywhere. This OBD extension cable is forked for diagnostics purposes, so it it not a pure cable extension. One end is plugged into a car, the other end is plugged into a OBD dongle / diagnostics etc. and the forked part leads to a custom diagnostic device (a CAN message logger).



I was put in front of this task, because we didn’t want to throw away hundreds of cables that were missing a few wires in the 1:1 extension part from the original manufacturing. I also hate creating more electronic waste. (It could have been repaired by the original manufacturer, but a container to China both ways would delay the delivery by 2 months or more.) So there is a new contract manufacturer that will get the cables, the missing wires, fit them and then test the proper connection. What would you do if you had to build the test device in just one day?


BOM and the schematics

I didn’t want (and have time) to build a device using a microcontroller, so I chose a ready made UTP cable tester. These testers are made for 8 wires cables and OBD II connector has 16 wires, so I needed two of them.


  • 2 pieces: noname UTP cable tester
  • 1 piece: OBD II connector
  • 1 piece: OBD II plug
  • 2 pieces: OBD II connector housing
  • 2 pieces: 1 meter ready made straight UTP cable




Proof of work




Maybe you have already used this idea in the past, but I just wanted to post this simple project to remind myself not to reinvent the wheel every-time I need to accomplish something.

What do you think? How would you build such a tester? Do you want to see more (the DIY CAN message logger)?


Thank you for reading and watching.