radio is on but no sound
 

so my cousin asked me to put in a new stereo in his 92 accord so he got the conversion connector that goes with the car and i use butt connectors to put the new stereo connector with the conversion connector and so i connect everything and hear no sound coming out... then after my cousin breaks the news that theres periods where the radios on but theres no sound, or theres times where you will hear a screeching sound then the speakers will work... i'm trying to figure out what coould be causing this to happen??... am i going to need to pull the whole dash??...anything would help... thanx in advance

Re: radio is on but no sound
 

1992 Honda Accord Car Stereo Radio Wiring Diagram

Radio Constant 12V+ Wire: White/Yellow
Radio Switched 12V+ Wire: Yellow/Red
Radio Ground Wire: Black
Radio Illumination Wire: Red/Black
Radio Dimmer Wire: N/A
Radio Power Antenna Trigger Wire: Yellow/White
Radio Amplifier Turn On Trigger Wire: N/A
Front Speakers Size: 6 1/2″
Front Speakers Location: Doors
Left Front Speaker Wire (+): Blue/Green
Left Front Speaker Wire (-): Gray/Black
Right Front Speaker Wire (+): Red/Green
Right Front Speaker Wire (-): Brown/Black
Rear Speakers Size: 6 1/2″
Rear Speakers Location: Rear Deck
Left Rear Speaker Wire (+): Blue/Yellow
Left Rear Speaker Wire (-): Gray/White
Right Rear Speaker Wire (+): Red/Yellow
Right Rear Speaker Wire (-): Brown/White