Does anyone know; on a 93 silverado which speaker wires are poitive and which ones are negative?

`wiring link for 95 https://www.modifiedlife.com/1995-chevrolet-silverado-c1500-car-radio-wiring-guide/

you should get a wiring harness to save you the trouble, however i just put in a kenwood in a 1997 thunderbird, if you cut the black wiring cover all the speaker wires are wrapped together and the other wires will be 12v constant acc, ground, etc. here is a diagram Car Radio Battery Constant 12v+ Wire: Green/Yellow
Car Radio Accessory Switched 12v Wire: Yellow/Black
Car Radio Ground Wire: Black/Light Green
Car Radio Illumination Wire: Blue/Red
Car Stereo Dimmer Wire: N/A
Car Stereo Antenna Trigger Wire: Orange/Blue
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A

Car Audio Front Speakers Location: Doors
Left Front Speaker Positive Wire : Orange/Green
Left Front Speaker Negative Wire : Black/White
Right Front Speaker Positive Wire : White/Green
Right Front Speaker Negative Wire : Black/White
Car Audio Rear Speakers Size: 5x 7 speakers
Car Audio Rear Speakers Location: Side Panels
Left Rear Speaker Positive Wire : Pink/Green
Left Rear Speaker Negative Wire : Pink/Blue
Right Rear Speaker Positive Wire : Pink/Blue
Right Rear Speaker Negative Wire : Green/Orange

I need to know the positive and negative speaker wires for the door speakers in my 1999 ford expedition xlt. Can anyone help please?

dont know about a or b but wiring should be color coded. these should be the colors and description for 02 silverado
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

dont know about a or b but here is diagram by color code

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

The yellow wire from the truck attaches to the red wire of the stereo. The black wire goes to the black wire. If the truck doesn't have a black wire, connect the black wire from the stereo to a bolt on the frame of the dash. The orange wire from the truck goes to the yellow wire of the stereo. Please let me know if you have more questions.

1991 Chevrolet Silverado C1500 Car Audio Wiring Schematic
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 Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
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: N/A
Car Audio Rear Speakers Location: N/A
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

connect the wires as indicated below

1999 Chevrolet Silverado C1500 Wiring, aftermarket stereo wire colors

Car Radio Battery Constant 12v+ Wire: Orange, yellow
Car Radio Accessory Switched 12v+ Wire: Yellow, red
Car Radio Ground Wire: Black, black
Car Radio Illumination Wire: Gray (Tape off) not used
Car Stereo Dimmer Wire: Brown (Tape off) not used
Left Front Speaker Positive Wire (+): Tan, white
Left Front Speaker Negative Wire (-): Gray, white/black
Right Front Speaker Positive Wire (+): Light Green, gray
Right Front Speaker Negative Wire (-): Dark Green, gray/black
Left Rear Speaker Positive Wire (+): Brown, green
Left Rear Speaker Negative Wire (-): Yellow, green/black
Right Rear Speaker Positive Wire (+): Dark Blue, purple
Right Rear Speaker Negative Wire (-): Light Blue, purple/black

I hope this would help you: 1999 Chevrolet Silverado C1500 Car Stereo 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 Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
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: N/A
Car Audio Rear Speakers Location: N/A
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

1990 to 2008 Chevrolet Silverado C1500 Car Stereo Wiring Guide
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: N/A
Car Audio Rear Speakers Location: N/A
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

Good luck and this should help

HERE IS THE RADIO 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 Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
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: N/A
Car Audio Rear Speakers Location: N/A
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