It's more than just tapping into the CHMSL but also a one way diode so that when the rear parking lights energise as the brake circuit is closed that it doesn't light up the front parkers or anything inside.
Also if you've noticed a Mazda CX5 brake lights, it's also how the light up their brake lights during the day time with the rear parking lights
Yep, this is what I was think as well. Back in the day I had a 1980 SR5 pickup with a camper shell on the back. It had a light inside but you had to manually turn it on after you opened the hatch. I added magnet switches to the hatch so the light would come on when opened but I powered it from the interior dome light of the truck. My thought was since I had the sliding glass window always open between the cab and the camper shell, I wanted to light it up when I opened a door. This all worked fine except for the fact that the dome light would also come on when I opened the hatch. A simple diode addition prevented this from happening so I can imagine how they could have done this in the new harness.
My concern is if my early Japanese built 2019 is wired like all the rest.
If anyone is interested, here is what I have deciphered:
Connectors N18 and M14 are in the rear fender areas and support the lights not on the hatch door. They have a 4 pin connector.
They are wired as such:
- Running Light
- Brake Light
- Ground
- Turn Signal Light
Connectors R6 and R7 are in the hatch area which includes the backup light and running light array. They too have a 4 pin connector.
They are wired as such:
- Backup Light
- Running Light (this pin also powers the license plate lights)
- ??? ( I couldn't find any reference to this pin in either connector.)
- Ground
I am comfortable about the rewiring of N18 and M14 and I can see where a diode would prevent the brake light from coming on when the running lights are turned on.
The issue I have is pin 3 of connectors R6 and R7. Mine has 4 wires in both connectors. What does this pin 3 do?
I understand that the new harness for the hatch bring the 12V signal down to R6 and R7, but what pin does it go to?
Also, as you can see in the picture, the 4 pin connector must be on a distribution board since the Blue and White wires are the backup light bulb socket and I would imagine that the Green and Black wires are for the running lights. Since they both need a ground wire, that makes 3 wires needed in this area. What's the 4th wire used for?
Sorry, I'm a technical writer and have issues with getting all of the details for a project.
Needless to say, I will be doing my research on the harness' once mine arrives on Monday from Amazon.