New HU = Dead Battery

[drew@dyermaker.cs.uoguelph.ca (drew)]

That would be fine except that John asked for an accessory circuit.  On
our cars, there isn't one - the closest thing is the key-in hot wire used
to activate the seat belt buzzer.  In fact, VW themseleves undertook to
use this same switch (key-in) for the radio power from around 1990 or so.

I have been using the circuit for years and years and have never had an
issue with a stereo - but I have always used units that have low current
inputs for the accessory circuit and high current circuits for the battery
lead.

If current draw were a concern a relay could be wired to switch battery
power using this lead.  I would recommend this if you had more than one
device that needed accessory input, for example.

If you want accessory, the seatbelt warning circuit is the one, and no
amount of probing with a test light under the dash will discover another
one.

Drew


On Mon, 21 Oct 2002, Vince Royer wrote:

> Guys, I strongly suggest that you don't hook the radio up to that seatbelt
> buzzer.  That's just not a good idea. Rather, run yourself a wire from the
> back of the fusebox.  There's a dozen or so unused metal pins on the back of
> the box, at least one of them will be a switched ignition.  Stick a female
> connector on the end of your wire, hook it up, and make sure you put an
> inline fuse on that wire.  Run it right up to the deck following the same
> route as the factory wiring.
> 
> Tapping into other circuits is just going to make a mess under the dash and
> risk drawing too much current out of them.  Drew is correct in saying that
> new head units don't draw very much current from the accessory lead.
> There's still no replacement for doing it properly, especially when it's
> about the same amount of work.  Just break out that test light and dig right
> in.
> 
> Vince
> 

Drew MacPherson - '84 Wolfsburg Edition Scirocco TurboDiesel