I'm trying to do the hardware bypass with grounding the parking brake wire and relocating/grounding the mute wire.

In the picture I attached, you can see what I am trying to do. I've connected the power/speaker wires from the F700BT to the Toyota harness that I got from Crutchfield. As such, there's a splice between the FT700BT and the harness ground wires. I've (temporarily) connected the parking brake wire to that splice, and my understanding is that not only do I have to relocate the mute wire, which I did, but also ground it, so I was going to connect that to the splice area as well.

Don't worry -- if this is the way to do things, the permanent connection I'll make will be much neater.

1. Is this the right way of grounding the parking brake and mute wires?

2. What is this mute wire used for, anyway? The installation manual says, "Yellow/Black - If you use equipment with a mute function, connect that equipment to the Audio Mute lead. If not, keep the Audio Mute lead free of any connections." Ironically, it seems that if you install one of these F-series units, I can't think of any other equipment that I would install.

3. (I think I know the answer to this, but I want to see if I'm right.) The install instructions say to move the mute wire out of the way if it's not being used. Why does it have to be grounded for this hack?

Yes.

You should ground the light green parking brake wire, the yel/blk mute wire (relocated from Pin 1 upper row to Pin 4 lower row in white harness) to the ground in the harness. Soldering is better than plastic wire taps. The rest of your harness looks professionally done so I think you're in great shape.

I have to chime in and tell you how awful that splice looks. Please don't put that picture on a resume

The mute wire is for things like an external bluetooth adapter or some other third party device which will need to mute the stereos audio. There is a setting that specifies what is muted when that pin is grounded, but other than that its useless except to steal to make use of the bypass.

You need to make sure you relocated the mute wire to the proper parking spot and make sure its firmly seated.. otherwise you'll have a doosy of a time diagnosing your problem should it not function.

Thanks for the replies. Don't worry -- the splice I showed wasn't the one that wound up in my car. I twisted the ground and parking brake wire together, and the other ground and mute wire together, and spliced them with a butt crimp device like the other splices I did.