Audio Systems: Loss of Low End/ Bass Rear Speakers, chrysler town and country, torch battery

Question
Hey.  I've been planning on replacing my factory CD player in my 1996
Chrysler Town and Country, but after taking it apart (removing it from the
front panel and looking at the wires) one too many times, I have loss back
low-end speakers.  Out of all the speakers in the van, only the front
windshield
two and the high back ones (near the farthest-back head rests) work (I am
not sure if there are speakers in each front door, but those are giving me no
sound along with the rear speakers (near the armrest/cubbies).

I did replace the stereo deck with a new faceplate, installed it myself and
connected all the wires correctly (I'm no pro for sure, but I can pretty much
figure it out for myself so far...)  I couldn't work out the radio system, but I
don't really care much.  I've found what looks like an 1/8th inch stereo jack
(it's about that size, but isn't exactly a stereo jack) hiding behind the front
panel that I've never noticed before, and can find no use for it.

Let me know what I could be doing wrong or how I can fix my little problems.

Thanks a lot!

Answer
Is the "spare" connector a RCA "phono" lead? If so it could go to an amp, anyway, using the std text below check the system out.
Peter

THE FOLLOWING IS THE PROCEDURE I FOLLOW IN A CAR I DON'T KNOW,

You will need;
An AA torch battery
Some paper / masking tape for labels
A pen
Paper to make notes
A 12v test probe, (like a screwdriver with a lead and clip on it and a bulb inside)
(Or a test meter set to 20VDC)

Favourite beverage x 4.

Speaker wires. These are normally twisted together in pairs if you are lucky and are the same colour for each pair but one with a colour trace on, i.e. blue and blue/white, green and green/white. (but not always) Touch a pair across the battery and you will hear a noise on the corresponding speaker, label it (e.g. left rear), continue until all four are identified and labelled.

Drink

Earth one side of your meter or tester to a metal part of the car, probe each wire until you have a wire that is live all the time with the ignition OFF, label this ‘+30’.
Switch on ignition and redo test until you find another previously dead wire now live, this is ‘+15’ accessory.
Switch off ignition and switch on the side / park lights, repeat test until you find a third live ( NOTE, if fitted, not always there), label this ‘dimmer’. Switch off the lights

Drink

You should now have two or three left. One will be earth, (usually black or brown); one could be to an amp and or electric ariel (usually blue or blue/white) and one for phone mute if fitted, (sometimes white but it would go to a phone holder or hands free unit). Connect your DIN plug to the correct wires, test and jobs a good un’.

Two drinks!

DIN connections are.

Speakers

Right rear -,  right front -,   left front -,  left rear-,
Right rear +, Right front +, left front +, left rear +

Power block viewed from cable side

Phone mute (white),/   n/c, /      ariel & amp (blue), /ignition (red)

N/c, / 12vlive, (yellow or orange), / lights, (various colours),/ negative (black)