Build your own OBD-II Harness/Adapter

Let's start with the basic disclaimer stuff... 

I'm not an expert, not a professional, just a guy who did these steps and it worked... if you follow these steps, hopefully it works for you too. If it doesn't, I'm not responsible for whatever happens - the harness doesn't work, you fry the ECU somehow, you open a portal to another dimension and alien unicorns conquer our planet... stuff like that. You're doing this at your own risk!

Tools:
Wire strippers/cutters
Needle-nose pliers
Molex crimping tool (not required)
Soldering iron (recommended, not necessarily required)

Parts used:
4-pin connector (link to part used; pin/wire size = 22-16AWG; insulation/seal size = 1.3-1.7mm)
OBD-II Cable (link to part used)

For the parts, if you have the spare wire sitting around, you can save a few bucks and buy just the female OBD-II connector and just run the 4 wires you'll need between the OBD-II and 4-pin connectors. You'll need to know what size wire you have in order to buy the proper 4-pin connector though.

Of the 16 wires on the OBD-II connector (OBD2C), only 4 are being used: 

• Pin 4 (Chassis ground; orange wire on OBD2C)
• Pin 6 (CAN [J-2234] High; green wire on OBD2C)
• Pin 14 (CAN [J-2234] Low; brown w/white stripe wire on OBD2C)
• Pin 16 (Battery power; green w/white stripe wire on OBD2C)

Again, I'm not proclaiming to be a pro, if you feel the need to criticize, by all means build one yourself and write up a better DIY.

1) Based on other guides, it was recommended to twist the pairs of wires. With this in mind, I removed the sheath and shielding from the wires on the OBD2C and separated the 4 wires to be used. I zip-tied the remaining 12 wires to keep them out of the way. 





2) The first problem with the parts I used is the wires in the OBD2C are 26AWG and the pins for the 4-pin connector (4PC) are sized for 22AWG so the wiring isn't quite big enough. The wires come pre-stripped with about 1/8" exposed. I stripped off more until it was about 3/8" exposed then folded it over on itself and twisted it to "thicken" the wire to better fit the pin. The 4PC kit comes with 4 rubber seals; slide one over each wire.


3) On the pins for the 4PC, there are 2 pairs of prongs (for lack of a better/proper term), one pair is folded over the exposed wire, the other pair is folded over the seal. Insert the exposed wire to line up in the front/first pair of prongs. The pic shows how small the wiring is compared to the pin connector itself. I had to use my needle-nose pliers to hold the wire in place for the next step.


4) I chose to solder the wire to the pin connector. I preferred the solid connection of the solder, plus the wire is so small I'm not sure how I could've crimped the prongs down over the wire without the solder holding it in place. My soldering skills leave a lot to be desired, but I've been doing it for various little projects on my bikes and luckily have been successful so far. Here's a YouTube video with some tips/tricks which I've found helpful.
Pardon the horrible photo; I took several and this was the "best" one.


5) For this step, if you have the proper Molex crimping tool then crimp the connector over the wire.

I didn't want to spend the money on a tool I only intend to use once. Using needle-nose pliers, at an angle, squeeze on one of the prongs to start folding it over onto the wire. Repeat for the other prong. YouTube to the rescue - here's a video I used to help with how to crimp the prongs over the wire. For extra measure, I used the pliers to crush the prongs down a bit further; admittedly, it's probably overkill at this point.





6) Slide the rubber seal up so that it fits between the 2 back prongs, use the same technique as before to fold the prongs over the seal.






7) I don't claim to know why, but in the other "how-to's" I used to create the harness, I saw it recommended to pair off the wires (in specific pairs) and twist them together. Pair off the wires in the following manner:

• Pin 4 (orange) / Pin 16 (green w/white stripe)
• Pin 6 (green) / Pin 14 (brown w/white stripe)

All done!






Successfully tested/used to check an error (I created myself  ) and clear it.




If something doesn't make sense let me know and I can try and take a photo of it or better explain.