I'm new here. Signed up here looking for some info regarding installing a after market Navi into my brother's 2004 Highlander V6 with JBL. I did not find it, but did figured it out on my own, so I'd figure I share the knowledge. Disclaimer . . . . this is all based on my own experience and what I encountered on my brother's car. Use at your own risk. I am not responsible for what you do to your car. With that being said . . .
I apologize that I do not have any pictures, because it did not occur to me that I would make a post about it. Also this is not meant as a DIY, just some info on things I encountered and might be useful if you are doing one yourself.
Anyways, the installation consisted of
1) Pioneer AVIC - x920bt
2) Boyo VTL420 back-up camera
3) Pioneer Ipod connector
4) Pac-swi-ps (Steering wheel controls)
5) METRA 70-8113 - Harness for the Radio
6) Metra 958202 - for the radio trim
The installation was pretty straight forward. With the harness it was pretty painless. I did not have to manufacture any trims or custom anything. Figuring out the wiring took by far the majority of the time I spent on the installation. Hopefully I can save you some time.
Here are some points of interest.
1) The harness did not have illumination wire, so I had to figure out which wire it was. It is the green wire on the stock plug next to the 12 volt wire. You will want to test it first. Just hook it up to a voltmeter and turn on the headlights. It should jumps to 12V. When you turn off the headlight it should go back to 0 volts.
2) The VSS wire is on the ECU module. The ECU module is behind the glove box on the right. You will see several modules. The ECU is the one on the left. There will be 5 plugs. The one you want is the second one from the top. It is a 35 pin one, and you want the 17th pin. It should be a yellow wire.
3) I did not find the reverse wire. According to Crutchfield it is on the driver side kickpanel. 12 pin plug, plug #10. Suppose to be a red/black wire. Since I did not find it, I just tapped the back-up wire (thick pink one) on the power bundle that plugs into the reverse bulb holder on the rear driver side. (I had the whole side torn up already to run the reverse camera wires.
4) I did the hack on the HU so it can play DVD and be moving at the same time. Search youtube and you will see how it is done. There is also another way if you don't want to hack up your plug. Supposedly if you use 2 staples and push into the tiny rectangular shaped hole under the wire, you can get enough force to push and release the wire but I can not attest to this because I did not do it this way.
5) The Highlander dash is hard to remove, so to hook up the NAV receiver and run the microphone wire, I found 2 unused holes on the driver side dash. I think on limited models it is suppose to be for some kind of sensor. On my brother's car there was just a plug there. Just push in the plug and run the wires from the top. When you have your radio out you, shine a flashlight from the top and you can see where the wires can go. Normally I use the passenger corner to put the GPS, but I did not want to have a wire running across the dash. But now that I think about it, I should have done that. The wire can be wedged between the glass and the dash. All you need to do is get some electrical tape and tape the wire in several spots make the diameter about 1/4 inch thick. About every 8 inches. Then you can wedge it between the window and dash.
6) The Boyo camera wire was not long enough so you will need to get a RCA extender cable and extend the power and ground wire about an extra 4-5 feet.
7) Please do yourself a favor and get wire tap splices. This will make your life so much easier and not have to cut up wires. Also it is easy to reverse if you ever want to put the stock radio back in (maybe for resale or trade in). Remember to test the connection with a volt/ohm meter (i used a paper clip to stick into the harness hole and use the ohm meter to test. That way if something is not working you are not going to have to tear everything back out and trying to troubleshoot it.
Good luck. Have fun and I hope this helps.
Let me know if this was helpful to you. If you have any questions I can try and answer them. But just a caveat, I'm not on here much at all.