Removing front and back speakers in 1991 Grand Am....
There is a lot involved in replacing these speakers. You should also know that the original factory speakers are 10 ohm speakers. This means that if you replace them with new speakers (most of which are 4 ohm) you run the risk of damaging the stereo, the speakers, or both. This can also cause a potential fire hazard in your car. If you want new speakers, you really should look at installing a new stereo as well.
To get to the back speakers, you will need to remove 2 bolts located under the front edge of the rear seat (bottom). After you remove the bottom, you will need to remove the rear seat (back). This involves removing the bolts that hold down the rear seat belts, which is a large sized torx bit (T-45, T-47, or T-50... Don't remember which). After removing these, lift straight up on the seat back to remove. Now remove the deck brake light housing, and the bracket that holds it. Now the deck cover can be removed. Be careful not to bend it too much getting it out from under the side trim on both sides.
For the front speakers, you must disassemble a good portion of the dash. Remove the screw holding the light switch and the wiper switch housings. This screw is underneath each housing. Once removed, there are dash mounting screws behind them. These screws (and many of the other dash screws) are a smaller torx-bit (T-10 or T-15, don't remember which). Sometimes they use a 7mm bolt. There is a cover panel just above the glove box. This panel is held on with 2 screws located in the glove box. After removing this panel, you will find 2 or 3 bolts holding on the dash. Last but not least, you will find 2 bolts inside each of the defroster vent grilles. These grilles just snap out for easier access to the bolts.
1991 Pontiac Grand Am Car Radio Stereo Audio Wiring Diagram
Car Radio Battery Constant 12v+ Wire: Orange
Car Radio Accessory Switched 12v+ Wire: Yellow
Car Radio Ground Wire: Black
Car Radio Illumination Wire: Gray
Car Stereo Dimmer Wire: Brown
Car Stereo Antenna Trigger: Pink
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: 4" Round
Car Audio Front Speakers Location: In Dash
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
Car Audio Rear Speakers Size: 6" x 9" Oval
Car Audio Rear Speakers Location: Rear Deck
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
on Feb 22, 2018