Ok so I wanted to post an updated wiring diagram because when I was researching for my own Eclipse I kept running into the same problems. One, some of the treads are super old and have links that no longer work. Two, a lot of older members would just insult new members for asking for wiring diagrams instead of just answering the question. Three, Mitsubishi did not use the standard color codes for their audio wiring which itself causes more confusion. I will try to keep this mostly text based so that anyone at any point in the future will still have access to it. I've also included pictures of several types of plug options you might come in contact with. Hopefully this photos will continue to be on this post with no problem in the future.
Mitsubishi Reverse Radio Plug
These are three types of plugs (these are the plugs that go into the back of your stock radio) your Mitsubishi might come with:
(looking from the back of the plug)
This plug comes on the Mitsubishis with the Infinity Amp. I simply refer to it as the GTS Plug
*Notice it has only four wire
The next plug would be found on GS model. So I call it the GS Plug
*Notice it has 12 wires
And the last one may be found on several different Mitsubishi models such as the Galant. So I call it the Galant Plug.
*Notice it looks similar to the GTS plug but has two key differences. 1) has five wires instead of four ( Pink Wire with Grey Dots for Amp Turn On). 2) The GTS plug has a Red Sleeve / White Stripe wire for memory and this one has a Orange Sleeve / Black Stripe for Memory.
2000-2005 Mitsubishi Eclipse Wiring Diagram
Infinity Radio Amp Equipped System
White Sleeve / Black Stripe = Red Sleeve Power
Red Sleeve / White Stripe = Yellow Sleeve Memory
Black Sleeve / Yellow Stripe = Orange Sleeve / White Stripe Dimmer
Green/ White Stripe =Orange Sleeve Illumination
Continue to the non amp powered system for speaker wiring guide
Non Amp Powered System
Yellow Sleeve / Red Stripe = Purple Sleeve Right Rear Positive (RR+)
Light Grey * Sleeve / Red Stripe = Purple Sleeve / Black Stripe Right Rear Negative (RR-)
Yellow Sleeve / Blue Stripe = Green Sleeve Left Rear Positive (LR+)
Light Grey * Sleeve / Blue Stripe = Green Sleeve / Black Stripe Left Rear Negative (LR-)
White Sleeve/ Black Stripe = Red Sleeve
Power
Orange Sleeve / Black Stripe = Yellow Sleeve Memory
Green Sleeve / White Stripe = Orange Sleeve Illumination
Black Sleeve / Yellow Stripe = Orange Sleeve w White Stripe Dimmer
White Sleeve / Blue Stripe = White Sleeve Left Front Positive (LF+)
Black Sleeve / Blue Stripe = White Sleeve / Black Stripe Left Front Negative (LF-)
White Sleeve / Red Stripe = Grey Sleeve Right Front Positive (RF+)
Black Sleeve / Red Stripe = Grey Sleeve / Black Stripe Right Front Negative (RF-)
^Pink Sleeve w Grey Dots = Blue Sleeve Amp Turn On (only present on the Galant Style Plug)
*very light grey where it can be confused for white
Mitsubishi Amp Plug
This is one of two plugs that connects to the Infinity Amp.
Orange Sleeve / Blue Stripe = Left Front Door Tweeter Positive (LFT+)
Brown Sleeve / Blue Stripe = Left Front Door Tweeter Negative (LFT-)
Orange Sleeve / Red Stripe = Right Front Door Tweeter Positive (RFT+)
Brown Sleeve / Red Stripe = Right Front Door Tweeter Negative (RFT-)
~Orange Sleeve / Blue Stripe = Center Dash Speaker Positive (CDS+)
~Brown Sleeve / Red Stripe = Center Dash Speaker Negative (CDS-)
~If equipped, the center dash speaker receives its signal from the left door tweeter positive and the right door tweeter negative.
Miscellanies
Pin #17 of 33-Pin Plug located in the Driver’s Kick Panel - White / Blue = Vehicle Speed Sense
Pin #9 of 43-Pin Junction Plug located in the Driver’s Kick Panel - Red / Blue = Reverse Positive (+)
At Parking Brake Switch Yellow / Green = Parking Brake
At Brake Pedal Switch Green / Orange = Foot Brake
Mitsubishi Reverse Radio Plug
These are three types of plugs (these are the plugs that go into the back of your stock radio) your Mitsubishi might come with:
(looking from the back of the plug)
This plug comes on the Mitsubishis with the Infinity Amp. I simply refer to it as the GTS Plug
*Notice it has only four wire
The next plug would be found on GS model. So I call it the GS Plug
*Notice it has 12 wires
And the last one may be found on several different Mitsubishi models such as the Galant. So I call it the Galant Plug.
*Notice it looks similar to the GTS plug but has two key differences. 1) has five wires instead of four ( Pink Wire with Grey Dots for Amp Turn On). 2) The GTS plug has a Red Sleeve / White Stripe wire for memory and this one has a Orange Sleeve / Black Stripe for Memory.
2000-2005 Mitsubishi Eclipse Wiring Diagram
Infinity Radio Amp Equipped System
White Sleeve / Black Stripe = Red Sleeve Power
Red Sleeve / White Stripe = Yellow Sleeve Memory
Black Sleeve / Yellow Stripe = Orange Sleeve / White Stripe Dimmer
Green/ White Stripe =Orange Sleeve Illumination
Continue to the non amp powered system for speaker wiring guide
Non Amp Powered System
Yellow Sleeve / Red Stripe = Purple Sleeve Right Rear Positive (RR+)
Light Grey * Sleeve / Red Stripe = Purple Sleeve / Black Stripe Right Rear Negative (RR-)
Yellow Sleeve / Blue Stripe = Green Sleeve Left Rear Positive (LR+)
Light Grey * Sleeve / Blue Stripe = Green Sleeve / Black Stripe Left Rear Negative (LR-)
White Sleeve/ Black Stripe = Red Sleeve
Power
Orange Sleeve / Black Stripe = Yellow Sleeve Memory
Green Sleeve / White Stripe = Orange Sleeve Illumination
Black Sleeve / Yellow Stripe = Orange Sleeve w White Stripe Dimmer
White Sleeve / Blue Stripe = White Sleeve Left Front Positive (LF+)
Black Sleeve / Blue Stripe = White Sleeve / Black Stripe Left Front Negative (LF-)
White Sleeve / Red Stripe = Grey Sleeve Right Front Positive (RF+)
Black Sleeve / Red Stripe = Grey Sleeve / Black Stripe Right Front Negative (RF-)
^Pink Sleeve w Grey Dots = Blue Sleeve Amp Turn On (only present on the Galant Style Plug)
*very light grey where it can be confused for white
Mitsubishi Amp Plug
This is one of two plugs that connects to the Infinity Amp.
Orange Sleeve / Blue Stripe = Left Front Door Tweeter Positive (LFT+)
Brown Sleeve / Blue Stripe = Left Front Door Tweeter Negative (LFT-)
Orange Sleeve / Red Stripe = Right Front Door Tweeter Positive (RFT+)
Brown Sleeve / Red Stripe = Right Front Door Tweeter Negative (RFT-)
~Orange Sleeve / Blue Stripe = Center Dash Speaker Positive (CDS+)
~Brown Sleeve / Red Stripe = Center Dash Speaker Negative (CDS-)
~If equipped, the center dash speaker receives its signal from the left door tweeter positive and the right door tweeter negative.
Miscellanies
Pin #17 of 33-Pin Plug located in the Driver’s Kick Panel - White / Blue = Vehicle Speed Sense
Pin #9 of 43-Pin Junction Plug located in the Driver’s Kick Panel - Red / Blue = Reverse Positive (+)
At Parking Brake Switch Yellow / Green = Parking Brake
At Brake Pedal Switch Green / Orange = Foot Brake