When a car stereo only works sometimes, the problem is usually in the wiring.
If you don’t find any problems there, you’ll have to expand your search.
Examine the wires on the back of the stereo.
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If the ground wire is loose, tighten it.
If it’s corroded, clean the corrosion and then bolt it back in place securely.
If the fuse was replaced with a circuit breaker, install a fuse instead.
If the fuse blows, you have a short.
Carefully inspect the power wire and replace if necessary.
Poor soldering, or loose butt connectors, can also cause a momentary loss of power or ground.
you’re able to also check for inline fuses, and check the fuse block.
If everything else checks out, you could have an internal fault in the head unit.
What Causes a Car Radio to Only Work Sometimes With No Sound?
One possibility is that the amplifier is going into protect mode.
If the radio cuts in, or out, suspect a crimped wire.
Open each door and look for the thick rubber boot that goes between the door and the car.
Move the boot back and forth, and see if the radio cuts in or out.
If possible, peel the boot back and physically examine the wires.
This may be difficult, as these boots are usually very stiff.
With the car radio on, tap on the interior of the door with your fist.
If the radio cuts in or out, suspect a loose or crimped wire.
