[s-cars] Questions about ABS disable switch installation (pagingFred Munro...)

[Keith Maddock (no reply)]

mlp5 said:
> Does anyone know if there would be some kind of additional input/control
> feature vis-à-vis turning ABS off in a 95.5 or latter EDL car?  i.e. with
> 95.5 EDL, if one were to turn ABS off, would the car's AWD via EDL also be
> gone?
>
> Mike wondering about the 95.5 wagon
>

For the Locker Diff (Non-EDL) cars:

Should be possible to wire this up fairly easily with a relay.  One of the
wires going from the diff locking mechanism must go to the ABS unit to
turn the ABS off when the rear diff is locked.  It's just a matter of
playing (or researching!) which wire this is (Scott J or Scott M might
already know) and the putting the relay in line with this wire (you'd have
to figure out first if you needed to ground it or give it 12V...)

Or you can always go with the method we use in the development cars for
wiring the Emergency-Shutoff-Switches (E-Switch, Big-Red-Button,
Oh-Shit-Switch), which is to install a relay in the main power supply to
the ABS computer.  (These are necessary when working with pre-production
development systems in case you encounter some "Unintended side effects"
of a logic change you just made ... :-D  )

I bought a switch here in Germany and will be bringing it back home with
me (I move back at the end of July! Yikes), so if nobody has figured it
out by then I'll volunteer to be the guinea pig :)

Yes, thats me, one of the biggest supporters of ABS (as it and its related
products are my livelyhood!) installing an ABS-off switch in my car, but
there are also definate circumstances where I want to be able to swtich it
off on the fly (and switch it back on), such as gravel roads and deep snow
as previously mentioned.

Anyway for the EDL cars - since the ABS unit won't have this input wire
for from the lockers, the best ways to disable the ABS would be to wire in
a relay to the main power.  HOwever this will also disable the EDL,
however that doesn't alter the AWD (IMHO) as you still have the center
torsen working for you...  Really for the circumstances that you want to
disable ABS, you can re-enable it for the few times when you REALLY need
EDL (launching when stuck in something....).

The problem here is that I think the EDL cars also did away with the
proprotioning valve, so the ABS is also playing a ´much larger "safety
role" here and you might end up with a very over-braked rear-end.

The other alternative is to wire a relay into one of the speed sensor
wires.  Depending on how Bosch / Audi set up the fault reactions of the
EDL and/or proportioning logic, you might be able to disable one front
wheel speed sensor, which might disable ABS, yet leave EDL and
proportioning active on the rear axle...  absolutely no guarantees there,
personally I wouldn't go that route at all....


-- 
Cheers,
Keith

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