89 405 Subwoofer install

Adam.Rodnitzky@AWL.COM
Mon, 20 Jul 1998 12:10:22 -0500

Hi everyone,

This past weekend, I installed a subwoofer (taken from my '96 VW
Jetta) into my 405. It sounded great, but unfortunately, about 10
minutes after the install, weird things started happening. Here is
what happened: I lost all reception on my radio, and the interior fan
would surge to top speed, drop back to the set speed, and occasionally
surge back up. So I disconnected the sub, and the problems persisted
for another 10 minutes or so. Since then, everything is back to
normal. I had the sub grounded to the chassis, and I powered it
through a fuse tap off of the radio fuse. I am guessing that is where
the problem came from. However, that is how it was wired in my VW
with no problems. I was theorizing that a similar situation to what
happened in old Maserati Biturbos was happening here: the PCB of the
fuse panel was getting overheated, and temporarily sending spikes
through the electrical system, in this case to the radio and interior
fan. Can anyone suggest a better place to get power from - and are
there any ways to activate an unused terminal on the fuse block (as in
the 405 DL model there are plenty)?

Thanks,

Adam