Okay, first things first. This is an intermittent problem. It started happening 6 months ago in my Tacoma. I sold the Tacoma, and moved my system to my Volkswagen, and the problem persists. It happens probably 2-3 times every two weeks. However, it is becoming more frequent.
First the information...
2007 Toyota Tacoma PreRunner
Replaced: Base stereo
2004 Volkswagen Golf GL TDI
Replaced: Base stereo - NOT THE MONSOON SYSTEM
Pioneer AVIC-F700BT (from SonicElectronix 2 years ago)
CD-IU230V iPod/iPhone interface cable (from Best Buy 2 years ago)
GEX-P920XM XM Tuner (from eBay - used)
iPod Classic 120GB 2.01 software
iPhone 3GS 8GB iOS 4.1 software
Stock speakers in all four doors
GM-D7500M Amplifier (from coworker)
TS-SW1041D Pioneer Premier 10" Subwoofer (from SonicElectronix 2 years ago)
Now the problem... While listening to music on the iPhone or the iPod. The left channel will suddenly drop out and become static at a very low volume. Switching between the iPod and the iPhone doesn't seem to make a difference. It happens on either one, but I mostly listen to the iPhone as the iPod stays at my desk at work. The only solution to this is to turn off the car and turn it back on. This doesn't always work either. I have double checked all the connections, and none are loose. One other possibly unrelated issue - the iPhone does not always charge. Sometimes I will get a message saying that the accessory does not support iPhone charging. These two issues rarely happen at the same time.