2007 sierra truck radio stopped working; told that all 4 speakers were gone; they came back on 6 days later for 2 days then went off again. What would cause 4 speakers to go all at the same time???

Bad solder joint in the radio. Chips don't come back to life when they die. Something that has to be searched for after the radio is tore down.

take it back to to the service center that fitted it and have it replaced or repaired
it points to something they have done or a faulty unit

try a new speaker on one of the speakers if it works replace all of them. often they will go out one by one until you notice when the last one goes out you have no radio

all the speakers and chimes stopped working.

Hi
It sounds like it would more than likely be a short from some where within the wires probably a speaker wire try turning the radio of then on whilst the ignition is on. Then turn the radio back up again.
Regards Craig

sounds like a computer problem or a ground issue, good luck

THE EASY ANSWER IS TO GET THE CAR ONTO THE DIAGNOSTIC MACHINE,THIS WILL TELL YOU WHAT(IF ANYTHING)IS WRONG.....NO GUESSING.....

Put a scanner on the car and see if there is a code set. I believe the car thinks the radio was stolen so it won't recognize it. If you can find a code reset it and you maybe ok.

check the fuses the chime comes from the radio and through the speaker, sometimes they have an electrical seizures when the batt goes low and you try to start

when mine stopped working,the right speaker, i removed the door panels then swapped the speakers. and still the right speaker didnt work. so i got a radio from a junkyard and installed it. and now all speakers work fine.