88 5kq - want to add oil pressure and voltage gauges
Huw Powell
audi at humanspeakers.com
Thu Jul 13 14:11:17 EDT 2006
> I want to add oil pressure and a battery voltage gauges on my 1988 5kq.
> The factory gauge cluster only has fuel and water temp gauges.
>
> I have an old (20yrs) Stewart Warner 3 gauge set (oil, water temp, voltage)
> available.
> All 3 gauge inputs are electrical.
> The electric gauge I would hook up to the alternator sensor wire post.
Or any "key on" hot wire would work (usually blue/black).
> I'm not sure what to do about the oil pressure connection. The original
> Stewart/Warner gauge came equiped with a rather large, leaky, mechanical
> "pressure/voltage" transducer. I'm assuming that inside the transducer was a
> mechanically operated variable resistor.
>
> I assume that the car oil pressure sender is of the idiot light design . .
> .on/off pressure switch, or is it?
Usually the set up is two on/off type senders, a low and "high" one.
They feed into a control unit that also gets tach information. At low
revs, the low sender must be triggered to fire the warning light/buzzer.
At higher revs, all that is needed is for the "high" sender to
trigger. I think they are something like 0.8 and 1.8 bar, but that is a
bit of a guess.
> In models with an oil pressure gauge, does the car not also have an idiot
> light warning for low oil pressure?
On oil pressure gauge cars, one of the senders has two connections - one
for the warning light system, and one that is variable for the gauge.
> Anyone want to discuss the Theory of Operation of the audi oil pressure
> transducer?
I think I just did...
> Maybe I can adapt the Stewart/Warner oil pressure gauge to work with the
> audi system - maybe a resistor network to modify the input signal - or
> replace/add an audi pressure transducer.
You might see if you can get a set of used type 85/89 auxiliary gauges
and senders - they might mount in your S/W pod if you are lucky.
The third gauge often found (on your donor Audis) is an oil temperature
gauge, which is driven by a sender mounted in the bottom of the oil pump.
Each of the two gauge circuits are driven by 12 volts applied at the
gauge; all three have easy to replace little bulbs in sockets. Often if
you find a donor set, you will also get a bunch of wires that make your
connections simpler (one ground, one power wire, one light wire, two
wires for senders). Just make sure that if you buy a set, it also
includes the oil temp sender and the two pin oil pressure sender. And,
ideally, some copies of the manual pages showing wire colors...
PS, I just installed a set of these along with one or two others in a
1957 Trojan loader instrument panel...
--
Huw Powell
http://www.humanspeakers.com/loader
http://www.humanspeakers.com/audi
http://www.humanthoughts.org/
More information about the quattro
mailing list