Electricals Again (Radio)

[mkb]

----- Original Message ----

From: Grant Lenahan <glenahan at vfemail.net>
To: mkb <mkb125 at yahoo.com>
Cc: quattro at audifans.com
Sent: Fri, October 15, 2010 12:50:25 PM
Subject: Re: Electricals Again (Radio)

These radios have two powered inputs - one that is always on, and one that is 
switched.

Some power is always present to maintain memory, etc.

When you turn the knob, or push the button, or whatever you do to turn it on, 
one of two things happens_

1. a switch on the knob shaft connects the full power to the amp/etc.
2. a relay closes and does the same (remember, there is supervisory power to run 
a relay)

I would guess the on/off/vol switch, or the relay, is kaput.  Buy a new one or 
have it repaired (probably cheaper to get a new/rebuilt one). Search the web, 
including ECS tuning, force 5 ( a lister i believe)

If you want to check your wiring further, measure from a solid ground to the 
input to the fuse. Measuring "across the fuse" brings into question what 
potential the unpowered side is at. Is there a capacitor there with residual 
charge? Maybe.  Who knows. Dont measure there. Measure to a known ground 
potential.

Grant

>>>>>>>>>>>

Grant,

Thanks for the info.  Looking over the service history of this vehicle, I see 
that the PO had replaced the radio because he was having the same issue, so I 
think I can rule out that option for now.  I'd have to look at the circuit 
diagram again to see whether there is a relay in play somewhere.

I know there is a known good ground point in the left A pillar wiring harness 
close to the fuse panel.  I'll likely measure there.  Appreciate the info.

--
mohammed
99 a6 2.8q avant
97 1.8qta