If you removed the Monsoon unit with the original factory plug it has four sections, there are some wires that are not used on the original monsoon plug.
DO NOT use the large GREY section of the plug (see picture below) it has wires with duplicate colors that are not used. Just match the wires from the monsoon plug to your original plug color for color, for example yellow on the monsoon plug to yellow on the Fiero plug, black on the monsoon to to black on the Fiero and so forth it is that simple, the orange on the monsoon plug goes to the orange on the SEPARATE TWO WIRE PLUG on the Fiero. When you run out of colors on the original Fiero radio plug you are Done wiring. You either have to remove the surround to install the Monsoon radio first or you have to trim the metal mounting tabs about 1/8 inch on each side if you do not want to remove the surround. You will have to use some 1/4 inch spacers behind the tabs tabs to make the radio mount forwards so it fit flush with the trim plate, make sure it is flush with the ac controller.
Monsoon Radio Wiring color code:
Radio Battery Constant 12v+ Wire: Orange
Radio Accessory Switched 12v+ Wire: Yellow
Radio Ground Wire: Black
Radio Illumination Wire: Gray
Stereo Dimmer Wire: Brown
Stereo Antenna Trigger Wire: Pink
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue
Pontiac Fiero Stereo Wiring Information
Radio Battery Constant 12v+ Wire: Orange
Radio Accessory Switched 12v+ Wire: Yellow
Radio Ground Wire: Black
Radio Illumination Wire: Gray
Stereo Dimmer Wire: Brown
Left Front Speaker Positive Wire (+): Tan
Left Front Speaker Negative Wire (-): Gray
Right Front Speaker Positive Wire (+): Light Green
Right Front Speaker Negative Wire (-): Dark Green
Left Rear Speaker Positive Wire (+): Brown
Left Rear Speaker Negative Wire (-): Yellow
Right Rear Speaker Positive Wire (+): Dark Blue
Right Rear Speaker Negative Wire (-): Light Blue
This is the adapter, you will not need it if you wire in the original monsoon plug to you existing harness, keep both plugs so you can have the option to go back to original.
Also you will need an antenna adapter.
[This message has been edited by Horse (edited 10-29-2015).]
