alternative oil pressure sender for $30?

Tony Lum tlum at
Sat Jul 6 09:40:26 EDT 2002

At 06:58 AM 7/6/2002 -0400, you wrote:

>2. Important.  do not disable that bulb... your alternator field wire is
>energised through it.  More when I'm of clear enough mind to understand
>it well enough to explain it...
>Huw Powell

Huw, you need to sleep more :-)  The alternator runs from the battery
light, the oil pressure light is separate.  Referring to page 97.181 of the
Bentley, you see that the warning light is connected to pin 6 (La) of the
oil pressure control relay along with the 0.3 bar low pressure switch.  To
me this looks like "wired OR" circuit, where either low pressure switch or
the relay can turn on the light.  In normal ops, the low pressure switch
should be open and out of the circuit allowing the relay to control the
light.  So in theory, troubleshooting the light should be routine.  Just
pull the relay and if the lights still on, then you really have no pressure
(unlikely because the oil pressure gauge is still working), a bad switch or
there's a short to chassis on the wire to the sensor.  That can be checked
by unplugging the wire and checking continuity to ground.  Ignition should
be off or you might fry your ohmmeter.


'83 Urquattro

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