This is how I added an AUX jack to 2007 Ford Taurus SE sedan factory audio system.
|9||Dk Blu/Wht||+R||AUX jack ring 1|
|19||Gry||-R||AUX jack ring 2|
|10||Wht/Pnk||-L||AUX jack sleeve|
|20||Brn/Lt Grn||+L||AUX jack tip|
Playing a CD selects the AUX jack input. "Real" or silent CD doesn't matter because the CD player audio is disconnected.
Essentially the in dash CD player is replaced by the AUX jack input.
AM/FM radio still works because it is actually in the rear control unit (RCU), along with the amplifier, that is mounted in the trunk.
Audio quality is on par with CD.
CD functionality could have been retained by using a 4PDT switch. Don't need a CD though when entire music library is at fingertips.
Could use about 10 db more gain. Other than that it is good and is still quite usable.
A TRRS jack is used to retain the balanced line capability. This was not a requirement. A TRS jack with both -L and -R connected to sleeve would have worked too. That is essentially what happens when a TRS plug is inserted into the TRRS jack.
Integrated Control Panel (ICP) Audio System Connector Pinout
|1||Blk||GND (behind center of dash)||11||Wht/Red||VBatt (hot at all times)|
|2||Dk Blu/Wht||Illum Out (interior lights system)||12||Blk/Yel||GND (behind center of dash)|
|3||Tan/Lt Blu||Disabled Ind (supplemental restraints system)||13||Lt Blu/Pnk||+ ACP (audio control protocol)|
|4||Lt Grn/Blk||ASYSON (audio system on)||14||Tan||- ACP (audio control protocol)|
|5||Red/Yel||VPwr (hot in start or run)||15||Gry/Red||?|
|6||Blk/Pnk||VPwr (hot in run or acc)||16||Red/Yel||VPwr (hot in start or run)|
|7||Dk Grn/Vio||Defrost Relay (defogger system)||17||Dk Blu/Org||Defrost Switch In (defogger system)|
|9||Dk Blu/Wht||+ Right Audio||19||Gry||- Right Audio|
|10||Wht/Pnk||- Left Audio||20||Brn/Lt Grn||+ Left Audio|