[urq] FW: Finally got the alternator warning light to shut up!

[k1drbar]

... I found the posts from before ... if you add the subject of this message
to an archive search you may find more info ...

Steve B
San Jose, CA (USA)

-----Original Message-----
From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf
Of Buchholz, Steven
Sent: Friday, February 18, 2005 2:31 PM
To: urq at audifans.com
Subject: FW: [urq] Finally got the alternator warning light to shut up!

... here's a post of a message I had sent during Tony's troubleshooting
series back in 2001 ... you can search the archives with the title of
this message to get all the related posts ... 
> 
> To my mind, Tony's fix for the light in the recent post [i.e. 
> installing a diode] is fixing a symptom ... it really doesn't 
> fix a problem.  Some time ago he also posted a note about 
> swapping two wires going into the fusebox, where Audi had a 
> small gauge wire hooked up to a high current pin on the box 
> and a higher current wire connected to a pin that attaches to 
> the same internal circuit.  I forgot that I had the wiring 
> diagram here ... it is the "run" switch on the ignition 
> switch (track 75) which is a 16ga black wire connected to pin 
> E2.  The 20ga wire supplying power to the seatbelt warning 
> relay (track 176) is attached to spade lug G3 (!) ... you can 
> swap the two to create a better situation.  I checked the 
> wiring diagram for my Fox ... and I think even some of the 
> newer cars with the underhood boxes ... same deal!  
> 

Steve B
San Jose, CA (USA)
_______________________________________________

-----Original Message-----
From: urq-admin at audifans.com [mailto:urq-admin at audifans.com] On Behalf Of
Buchholz, Steven
Sent: Monday, December 10, 2001 9:56 AM
To: urq at audifans.com
Subject: RE: [urq] Finally got the alternator warning light to shut up!

Thanks Tony for researching this issue fully and telling us what you
learned!  I really appreciate this sort of post because from my POV, it is
one of the things that makes this list valuable for all!

The fact of the matter is that the wiring change that you did does provide a
better solution in terms of current capacities of wires and requirements as
compared to the way that Audi wired the box.  I plan to do a very similar
mod to my car when I clean up the electricals.

In the final analysis, what you learned was that the alternator light that
glows dimly with the turn signals is not an indication that there is a
problem in the electrical system.  This has been my feeling all along since
it didn't go away when I went through my connectors, fuses and grounding
years ago ... but it is good to have the full analysis now to back it up!

Steve Buchholz
San Jose, CA (USA)
>
> Some of your may remember my previous post back in September about the my
> problems with the alternator warning light and the extensive mods I made
to
> get rid of it.  Well I thought I had it nailed (at least the turn signals
> weren't altering the engine's idle speed), but with the short daylight I
> noticed I was still getting a dim alternator light with the headlights on
> and turn signals running.
>
> My voltmeter was still indicating nearly 14 volts, so the alternator
wasn't
> the problem.  I measured the voltage on the 15 bus (at the dummy upshift
> relay plug on top) and at the 61 terminal (on the oil pressure relay
socket
> on the bottom).  These terminals are the ends of the alternator warning
> light.  I found that the 15 bus was dropping to 11.5-12V once the turn
> signals were switched on while the 61 terminal was pretty close to
> 14V.  The dim alternator light was the result of 2 volt reverse
> differential.  In other words, the current was flowing backwards towards
> the warning light is just enough to dimly light the bulb and irritate the
> heck out of me (I hate driving around with any red lights in the
> dash).  The 15 bus at T12-11 is fed from the the turn signal switch
> (current track 112), so the source supply to the instrument cluster would
> always drop when the turn signal load was added.  I could provide another
> separate 15 bus but this would require another relay and more wiring.
>
> The simplest solution was to install an addition blocking diode to the
> T12-2 output wire.  I cut the wire and crimped M and F disconnects on
> either end of the wire.  I then took a 3A rectifier diode (Radio Shack
part
> no. 276-1144) and crimped matching connectors on each lead, keeping the
> polarity such that the anode was connected to the instrument cluster and
> the cathode went into the wiring harness.  If this mod created any
problems
> I could simply remove the diode and plug the harness back together
> again.  The forward voltage drop of the diode has not affected the
> alternator startup circuit and the parking brake and coolant warning
> flasher lights still operate correctly.  The alternator light still comes
> on with the key on and the engine not running as it should.  The good news
> is the alternator light is now completely off  once the engine is
> running.  Lights on, high beams, turn signals, warning flashers, brakes
> etc. it didn't matter.  I dimmed the instrument cluster illumination all
> the way and pulled a jacket over my head  just to be sure.  It is out,
out,
> OUT!
>
> Regards,
>
> -Tony
> ur-quattro #900302
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