[s-cars] ABS-OFF switch

[jpb3wvu at frontiernet.net]

Igor,
The "ABS off" light does indeed illuminate on start up and then
quickly disappears after the 95.5 is started.  I loved this
feature in my 1990 V8, it sure is helpful to turn that ABS off
in snow most of the time. Could you direct me to the write up
you used?  Thanks.

John




> ----- Message from KBATPO at comcast.net ---------
>     Date: Mon, 20 Dec 2004 00:34:44 -0500
>     From: Igor Kessel <KBATPO at comcast.net>
> Reply-To: Igor Kessel <KBATPO at comcast.net>
>  Subject: [s-cars] ABS-OFF switch
>       To: Audi S-list <s-car-list at audifans.com>
>
> Folks,
> I have finally decided to retrofit the ABS-OFF switch into my
> '97 S6.
> Generally I used Fred's brilliant approach. The only
> difference was the
> donor switch. Fred used the Fog Light switch to bastardise and
> I used
> the Rear Defroster switch. In retrospect I wish I had used the
> Fog Light
> switch as well since it has a second indicator bulb which
> lights up when
> the switch is activated, but I couldn't find one in the U-Pull
> It yard
> that I scavenged.
>
> However I ran into a peculiar problem, which is unique to my
> particular
> car. My car originally came with the digital metric-only
> Instrument
> Cluster. I replaced it with a mechanical cluster off a wrecked
> '94 S4
> when I brought the car into the country and federalised it for
> PennDOT.
> I also heavily modified this cluster by building in the 20-LED
> Lambda
> gauge, the WGFV LED and a voltmeter off my '97 cluster in
> place of the
> stupid clock. Oh' and since now I had the actual functioning
> oil
> pressure gauge in the older cluster, I also bought and
> installed a '91
> Audi 200 oil pressure sender into the plugged port in my car,
> ran a wire
> from the engine compartment, populated the empty position #2
> in the
> black 4-pin plug and connected it to the cluster. So now on
> the right I
> have three real gauges. Can you say "Frankencluster"? :)
>
> The '94 S4 cluster was a direct match for my '97 S6 and has
> worked
> perfectly well. Or so I thought up until yesterday. I retrofit
> the
> ABS-OFF switch along with the relay per Fred's Munro excellent
> colourful
> pictorial write-up in the Acrobat format. When I depress the
> switch OFF
> and back ON I can hear the ABS pump going through the
> initiation
> routine. However the ANTILOCK OFF signal lamp in the
> Instrument Cluster
> does not come on. Turns out that it never did. Not with the
> '94 cluster
> anyway. I never even noticed its absence on the initial
> start-up for all
> those years that I owned the car. The ABS worked fine thus I
> never even
> suspected anything.
>
> I will leave out several hours of tracing the problem in the
> Bentley
> schematic diagrams. I discovered that in the '94 cluster one
> terminal of
> the ABS K47 signal lamp is connected to the bus 15 (+12v when
> the
> Ignition is ON), and the other terminal is connected to the
> pin #13 of
> the red T26 connector on the back of the cluster. However in
> the '97
> cluster one terminal of the ABS K47 signal lamp is still
> connected to
> the bus 15 (+12v when the Ignition is ON), yet and the other
> terminal is
> connected to the pin #19 of the red T26 connector on the back
> of the
> cluster. Lovely. In both clusters the corresponding wire in
> the plug is
> YEL/RED. Only the pin that it was connected to was different.
> Bizarre.
>
> Just in case I checked the position #13 in the male plug of my
> '97
> harness. It was empty. The position #19 was populated with the
> proper
> YEL/RED wire.
>
> Since I don't have a '94 S4 to test the harness I had to go by
> the
> Bentley manual. It states "#19 - NOT USED". So far so good.
>
> I promptly opened up the cluster and soldered a jumper wire
> from pin #13
> to pin #19 on the PCB side of the red T26 female connector.
> Reassembled
> the cluster and installed it in my car. Turned the ignition ON
> and got
> the ANTILOCK OFF light. Finally! Started the car and
> discovered that the
> light failed to go out. Exercised the ABS-OFF switch and heard
> the
> unmistakable clicking of the ABS controller initiation
> routine. Strange.
>
> That day I also installed the Low Beam rotary switch, which
> allows to
> dip my Xenons according to the number of passengers in the
> car. I
> decided to test this feature. When I turned the lights ON the
> ANTILOCK
> OFF light went out. And vise versa. This was getting stranger
> by the minute.
>
> OK, back to the drawing board. I completely disassembled the
> cluster
> again, and painstakingly scraped the conforming coating off
> the PCB for
> the K47 bulb's track just to trace the damned thing. It turned
> out that
> although Mr. Bentley said "NOT USED" for the pin #19 in the
> '94 cluster,
> in actuality for some unknown reason the pin #19 was
> internally
> connected to the pin #22. Yes, you've guessed it right, the
> illumination
> dimmer circuit.
>
> Exacto knife in hand, I cut the illumination circuit off pin
> #19.
> Reassembled the cluster again (are you counting, folks?) and
> connected
> it to the car. No more ANTILOCK OFF when I turn the lights on.
> Hell, no
> more ANTILOCK OFF light, period. Even with the ignition ON.
>
> At this point I realised that I ought to start from the other
> end. The
> K47 bulb does indeed see +12v, since it sits on the common bus
> with the
> alternator's indicator light K2, and this one does come on
> when the
> ignition is ON. I guessed that the YEL/RED wire in the red K26
> plug
> fails to provide the GND to the bulb when the ignition is
> turned ON. In
> order to test this theory I stuck a needle into position #19
> in the plug
> and connected a test light to it. I connected the other end of
> the test
> light to +12v. Turned the ignition ON. The test light did not
> light up.
>
> This YEL/RED wire goes to the J104 ABS controller via the blue
> plug #6ac
> in the Connector Station I under the dashboard. I guess my
> next step
> would be to check the continuity of this wire from the
> Instrument
> Cluster in the torpedo all the way to the ABS controller under
> the rear
> seat.
>
> Before I start tearing the car apart, can some kind soul with
> a '95.5 S6
> tell me if the ANTILOCK OFF bulb does indeed illuminate when
> the
> ignition is turned ON and subsequently goes out when the car
> is started?
> I am hoping I didn't burn anything yet...
>
> Thanks for listening, folks.
>
> --
> Igor Kessel
> two turbo quattros
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> ----- End message from KBATPO at comcast.net -----