Front left speaker/tweeter back to life after high volume?

Question

I drive a 2014 Corolla LE with around 20,300 miles.

Noticed that my left front door speaker did not work. Also the front left door tweeter(attached to the door) emits a faint rendition of music playing. All other speakers/tweeters are working.

Today,having tinkering around, I set the speaker fade all the way to the front right(where the dead speaker and dying tweeter are) slowly to max volume when suddenly both the door speaker and tweeter come back to life.

Question:

What might have caused my speakers to stop working, and why did the focused volume bring my speakers back to life?

I will see if it goes silent again and will update. Thanks.

Answer 1

When you are playing music at low volume the voltage into the speakers is low .This low voltage means that any dirt or corrosion will stop the sound from coming through .A higher voltage will sometimes be enough to microweld the bad contact .This was well known in telephone engineering circles even in the 1800s .DC was and still is placed on the telco line to provide what was sometimes called a sealing current .The turn on thump of some old Solid State car radios would help in this respect .The volts needed to seal a bad contact varies a lot depending on the metals involved .A ballpark figure is 8 Volts .This is why 6V cars have more electrical contact unreliability than 12V cars .This explains why turning up the radio worked for you .Many car audio systems will peak at say 12V, some will make much more .Sometimes the offending joint is on the speaker cone itself where more volume gives more vibration .I hope it is not because those joints can be tricky to resolder .

Answer 2

Sounds like an intermittent wiring fault. Pprobably a broken wire in the harness that connects the door to the vehicle; the door opening and closing puts repeated stress on the wires until they break.

The problem could be caused by a dirty volume potmeter, where rotating the potmeter vigorously can clean the contacts sometimes. But that's IMO less likely than a wiring fault plus coincidence.