Colin,
Despite the fact that the plastic switch has two leads on top of it, you are
correct, they are connected and it doesnt matter which one you attach the lead
from the wiring harness to. The switch is triggered by the shuttle inside the
PDWA which has a thinner part in the middle and thicker part on either end. In
its "normal" operating position the shuttle is centered and the thinner part
allows the plunger on the plastic switch to remain lowered. When there is an
imbalance in the braking system and lower fluid in either the front or rear
braking system then the shuttle is pushed to one side or the other, pushing the
thicker part of the shuttle towards the center of the PDWA and pushing the
plunger on the plastic switch up, triggering your brake light on your dash so
you know you have a problem with the braking system. While the system will work
just fine, I would think the lack of front brakes would be noticed by how your
car DIDNT stop when the brakes were applied, before y!
ou ever had the chance to look at the light on the dash. Now the rear brakes
failing would trigger the light on the dash and you wouldnt be as likely to
feel the difference and you might not notice the difference until the light
went on the dash. Maybe others who might have been through such a failure might
be able to relate their personal experience. Hopefully this makes sense and I
have answered your question. If not then just let me know and I will try again.
Aaron
Aaron Cropley
71 TR6 (Throttle Body Injection!)
http://www.triumphowners.com/108
Topsham, Maine
-----Original Message-----
From: colinthom@shaw.ca
To: 6pack@autox.team.net
Sent: Thu, 9 Nov 2006 9:28 PM
Subject: PDWA
How the hell does this thang work? There's the plastic fitting that
screws into the brass valve body. On mine, it has a spring-loaded
plunger that sits inside the brass valve body, and on the other end of
the plastic fitting are two terminals with continuity between them. When
I push the plunger up with my finger so that it comes into contact with
the small strip that links the two terminals, there's still continuity.
There's a rubber plug with two holes in it that fits over the plastic
fitting with the two terminals. On the other end of this plug, there's
only one hole. It appears that the wiring harness connector is anchored
in this plastic plug, and thereby connected to one of the terminals on
the plastic fitting that screws into the brass valve body. There's a
plastic clip thing that clips the rubber plug to the plastic fitting so
it doesn't come off. Why not just push the wiring harness connector
directly onto one of the terminals in the plastic fitting? And, why are
there 2 terminals in the plastic fitting when there's only one connector
-to fit one terminal only-on the wiring harness connector? Mine's never
worked since the rubber plug was blocked by the remnants of the old
wiring harness connector, but now that all the pieces are free and
clear, I can't figure out how it works with continuity present between
the terminals, regardless of the position of the plunger. Can someone
'splain this? Many thanks. Colinthom@shaw.ca
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