cold solder joints
I fixed mine as well by carefully resoldering the amp board , it solved 99% of my ACC problems , I love the fact that all these little parts can be taken apart and fixed . At the moment I am fixing a weeping aux water pump on the 300CE by replacing a 5 cent O-ring , any other car would have a sealed unit that couldn't be taken apart without self destructing , eg Ford or GM .
1985 380SE- 160,000km 'Blistu' - Sold
1988 300CE- Eva,my garage mistress
2007 R350 4matic- The Black Pearl
2011 Ford Ranger-Work truck
1974 25' Trojan Sea Raider- 'Grannyknot'
2002 215 cm Atomic DH skis- Canadian SDH record holder, 175.5km/h- Vars 2010