Leaving work I noticed the driver's side speakers were silent while the passenger side working fine. As I drove, it crackled a bit every now and then with the music coming in and then cutting out, mostly cut out. It's both the tweeter and midrange doing it in unison, so unlikely to be 2 faulty speakers(?) Sounds like a lose connection, but how on earth do you troubleshoot that if it could be anyway between speaker and headunit? I sat with the door open and prodded the cables passing from door into dash, but couldn't provoke or control the symptom. I changed the headunit a few weeks back, upgraded from a Swing to a Columbus, could I have disturbed the quadlock wiring and something worked lose? For that matter, do the speakers even wire directly into the headunit, or do they go via another electrical box first?

 

I have no experience here, so wondering if it's something that can be chased, or better to send it into the garage to be looked at.

firstly take out the headunit and make sure the quad block is in correctly. afaik the speakers go direct, there is no crossover or anything as the tweeters have a capacitor wired to block the low frequencies. 

 

Next, take the door card off and check the connections. The mid connection is actually accessible with the mid still in place and the tweeter you need to disconnect to remove the door card

...and in typical unexplainable fashion, the speakers worked fine this morning! At the weekend I'll go through and check the headunit and speaker terminals.