I have checked this out and ppl say it is the same as for a D3

but I have this rca harness

It does not have a open slots like the D3...It does have

2 open slots but they are not on the edges. Any help plz?

For the D1 and D2 units, you use the empty slot next to the ground wire on the other (power/speaker) harness instead.

There is a slot open next to the constant wire

But on the bottom, next to the ground is another ground.

So im gonna ground those and the brake and see what happens.

Is the unit used? Because if it is it might have been bypassed already.