My stock radio works well and was thinking of adding the CD changer, amp and subwoofer. The radio has the CD button and the blue CD changer cable was run from the back of the head unit to the back of the car. Question is there is no plug for the amp other than what looks like an old style plug like the ones used for a computer monitor or a printer. Does anyone know what factory amp was used and what this dangling plug was supposed to be used for? All the factory amps I see on ebay have a standard plug none like the one that's hanging loose from the top of my gas tank? Thanks

 

You would ideally need the Harmon Kardon wiring loom. The standard stereo has the speakers wired forward to the head unit in the centre console. The Harmon Kardon system has the speakers wired to the amplifier in the boot, with a pre-amp feed coming from the head unit in the console to the amplifier in the boot. The wiring is not pre installed in non premium stereo vehicles.
You could make your own cables easily enough, but installation is not a 5 minute job I'm afraid.

 

...and that "old style plug like the ones used for a computer monitor or a printer" you see dangling up under the parcel shelf in the trunk is for the in-car mobile phone, not audio. The other end of that cable is in your console though, ending in an RJ45/48 female jack for the Jaguar phone.

 

In car Ethernet!

 

Difference Between RJ45 and RJ48 | Difference Between | RJ45 vs RJ48

Since this is a phone cable, it likely is meant for RJ-48, but it may also be completely custom terminated since it was for a Jag phone and terminates in that D-shell connector. Only way to know would be to tone it out.

But yep, conceivably you could re-terminate the D-shell end with another RJ connector to whatever standard you need once you verified the cabling at the head end and accounted for what pairs went to which pins.

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