- Aug 30, 2020
Pre-Writeup (Part 1)
Here in a month or so I am going to be installing a new stereo system in my 2006 Signature L Town Car. I wanted to put together a pre-writeup of the plan for my own organization and to get any feedback anyone has. I will update this after the job is done to serve as a guide for others.
Overview & Goals
The objective here is to do a proper and near seamless upgrade of the stereo head unit to keep a factory look and feel to things. I am intentionally not cutting any corners and trying to get the best possible results.
My TC has the THX system with Navigation. This is the most complex and difficult system to work with from what I have found. Briefly, it consists of a head unit in the dash, a navigation unit in the trunk, and an amplifier also in the trunk.
With this system the speakers are driven by the amplifier, not the head unit, so any new head unit must either run new wires to speakers, or use the existing wiring to the trunk amplifier. Because of the difficulty and risk of damage in disassembling the car enough to run new wires (plastic clips get brittle with age) I am going to use the existing speakers and amplifier. Being a THX system to start with, I assume the speakers and amplifier are of good enough quality that a considerable sum would have to be spent to actually improve them.
The head unit is another matter. Beside the fact that it no longer reads CDs and has out of date navigation, it also does not support many contemporary features that would be a nice upgrade to the TC. So it will be replaced.
I am also going to add a backup camera as part of the upgrade to aid in parallel parking.
Annotated Shopping List
I have chosen the Sony XAV-AX5500 head unit. Criteria for this decision include
Brand-While I don't think brand has a great deal of meaning these days I do distinguish between mainstream brands and the more "cut rate" versions. Sony is a an established brand and I have good experience with their other products.
Reviews/Ratings-In looking at reviews and ratings I found that while units like BOSS had lots of ratings (due to their lower price points and presumably more sales) many reviews were not detailed or did not reflect longer user experience. And those that did were often less favorable than the more reputable units. My advice here is to look at what people wrote more than the distribution of the reviews or number of reviews.
Size-Double DIN, in other words, the same size as the factory radio. For appearance, screen function, etc. double DIN is a must.
Touchscreen Technology-Capacitive, ie the same thing as your smartphone. Resistive is so bad as to not even be a serious consideration.
Inputs-Two USB inputs was a major consideration for me, as I want to be able to jump in the car and go without bothering with a phone sometimes as I do in my other car. So that means having a thumb drive in a USB port with my music. But having only 1 port means swapping between that drive and the phone when I want to use that. So having 2 ports gets the best of both worlds, plug the phone in when I want to and leave the music drive in at all times. Having a backup camera input is also required.
Outputs-Must have pre-amp level outputs for the 4 channels and subwoofer
Android Auto-Unit supports Android Auto which I find useful for road trips. Does not support the wireless version however my research indicates that 1) the wireless version is much more bug ridden than wired 2) relatively new and expensive phones are required for wireless use and 3) head units that support wireless are quite a bit more expensive for that feature. Additionally, my view is that on a longer trip when I would likely use it, wireless will drain phone battery requiring me to plug it in anyway, so what is the real point?
Physical Buttons-While it unfortunately omits the volume nob as basically every double DIN unit now does, this unit does at least have some physical volume buttons which I consider easier to find and press than a purely touch screen interface.
Configurable Steering Wheel Buttons-The head unit itself can remap steering wheel buttons, which I intend to use so that the voice button is useful (hopefully I will be able to use it as a "hey google" in android auto but time will tell)
For the backup camera I selected a Boyo VTL17ir. This is a license plate mounted camera which works well with the Town Car configuration, it also has an IR for night vision. I don't consider top image quality important for a backup camera, it's just there to see reasonably large objects, and factors like rain/mud/snow are more likely to impact the image quality than anything else.
One key feature of this camera which is not shared by all of them is the use of a proprietary narrow connector that joins the wiring to the camera wire pigtail. This is a good design as it makes the hole you need to put the wire through smaller.
Steering Wheel Controls Wiring Interface
To retain steering wheel controls I am using a Crux SWRFD-60L. This wiring interface connects to the 24 Pin wire harness in the dash (C2253A) and provides several wire connections from that harness to the dash. It also provides a "magic box" with some circuitry that converts the resistive steering wheel control output to a standard protocol that the aftermarket head unit can use. Finally, this unit includes a 12v to 5v dropdown resistor that can be used to turn on the subwoofer. (Note, that that both Crux and Crutchfield say this unit is not compatible with Sony/THX systems, however according to the Crutchfield techs this is due to it not providing the pre-amp connections required, the steering wheel control and other connections still work).
USB Surface Mount Port
This is a surface mount USB 3.0 compatible port with a 3 foot cable that ends in a male connector. This port will be used for the smartphone connection.
Deutsch DTM 6 Pin Harness & 12 Pin Harness
Because several of the wire harnesses used on the Town Car THX system do not have any aftermarket solutions, they require the removal of the factory connectors to make the required connections. While this could be done directly by adding RCA plugs and other connections directly to the factory wiring this presents two issues. First is the relative difficulty of doing such soldering on wires attached to the dash. Second is the inflexibility of the system for any future changes such as a different head unit. Third is the limited amount of factory wire slack available.
To remedy this, a set of generic connectors (male and female set with wire pigtails) will be used to make the connections, allowing for simpler wire to wire soldering on the factory lines, adding slack, and making the system reconfigurable with a minimum of fuss in the future. Two connectors are used for two different factory wire harnesses.
Right Angle RCA Plugs
Pre-Amp outputs from the aftermarket head unit as well as the backup camera input are all RCA jacks. To reduce the space required behind the head unit (which some have commented is so little as to require cutting plastic away) a set of right angle RCA plugs will be used.
Right angle 3.5 MM mono plug
The stereo comes with a mono microphone connected by a 3.5 mm mono plug. Because my install plans to use the factory install this microphone will be replaced with the stock microphone input supplied from the trunk via a wire harness patch job. As a result, a new solderable plug is needed to make the connection at the head unit.
Female RCA Plug
A set of male and female solderable RCA plugs for use with the backup camera video. Rather than run a new wire though the entire car I am going to use the navigation system wiring (which carries video in the stock system) to carry the backup camera video signal. To do this a new male and female solderable plug will be needed to terminate the wire from the camera and create a jack attached to the stock navigation system video wiring.
A universal antenna extension will be used to make installing the head unit easier by increasing the slack on the factory antenna cable which has been described by some as insufficient.
For installing the backup camera T Taps are used to connect the backup camera wiring to the 12v and ground connections of the reverse lights to power the camera when in reverse and generate a signal for the head unit to switch to the backup camera. This signal is also conveyed via the stock navigation wiring which is no longer used with the new head unit so no wires need be run through the vehicle.
For insulating and reinforcing splices and connections throughout the new installation to increase reliability and durability. A large box with a wide variety of styles is used.
For securing wiring as needed.