I installed the Canadian OEM Mazda hitch wiring harness (00CT-88-C57H at least from Scarboro Mazda) today. Should have taken less than 2 hours, but got sidetracked by a chatty neighbor and a small problem.
As others have noted, the instructions are missing key details. I used the US instructions for better details on the trim removal in the cargo area (that's all that's needed for the CAN version, other than loosening the rubber gasket around the back of the left passenger's door). I had also done speaker upgrades in my previous 2016, and this was somewhat the same in how things are removed/fit together.
Things that might be useful for others:
--I literally just got the harness. No ties, no foam pads, no 4 wire flat connector hitch bracket, nada but the wiring pieces themselves. No biggie, as I already had ties and foam pads in my garage to use. Also, it makes sense that the bracket wouldn't be included since that's specific to the Mazda hitch, which I don't have. Easy enough to get a universal one.
--A bit confused by the fact that the inside connector for the separate wiring that goes to the outside of the car with the 4 wire flat connector didn't fit through the pre-existing opening in the car floor after removal of the grommet. Oh...the wires pull out and are then put slotted back in, but that's not directly stated in the instructions. Not sure if that connector should usually be separate to start or not. The little rubber stoppers meant to hold the wires in the connector didn't work well for me--when I tested after install but before putting everything back, the left signal wasn't working. Bad connection. Ended up using electrical tape to hold the wires in place on the connector.
--I thought I didn't get the replacement grommet for the new harness where it goes through the cargo floor to the underside of the car. I thought was clever and used the existing grommet instead by cutting a small hole out of the center and forcing the wires through. Mildly annoyed to then find that the grommet was already on the wiring loom itself and I missed it. DUH.
--One final circuit test before putting everything back, and I accidentally and stupidly touched the ground with the other wire. ZZZZT. Blew a fuse. But what fuse? The CAN harness is wired into an existing empty connector for power inside trim but the instructions don't tell you which circuit. Took a chance and tried the fuse noted in the US harness instructions in the troubleshooting step--turns out to be the same 15 amp one, luckily. I want to say it is in slot 5 of the interior fuse box.
--Everything went back together well. Did not want to drill into under bumper as the instructions direct and found that instead I could attach the harness over the front of the driver's side hitch arm (facing the back of the car) and well out of the way of the exhaust system. I also routed the wiring up and over a driver's side bumper support bracket so no part of the harness is anywhere near the exhaust or muffler.
--Waiting for stainless cable ties to arrive, so just temporarily used plastic ones to hold the harness. Will likely leave those and just add the stainless ones, and will also use the metal ties for attaching the universal bracket I ordered for the 4 wire connector end. I will likely have it on the flat face of the hitch arm pointing downward, so not below the bumper line (not sure about the OEM hitch, but the horizontal parts of the Draw Tite I installed sit above the lower bumper line. That way, the connector is mostly visually hidden from behind and above but still easily accessed when needed.
--I found this video useful mainly in terms of visually seeing how to deal with that black locking arm over the gray wiring loom, and also a better idea of what wire connectors are involved. Otherwise, I found it a bit confusing and choppy:
https://youtu.be/2aLBMQMDI7M