Hi John.
The PDWA circuit works like this: One side of the warning light is connected
to +12V. The other side is connected to the PDWA switch. The other side of
the PDWA switch is connected to ground. When the PDWA is off center, it
throws the switch which grounds the light to complete the circuit.
I'm not sure where you are checking for continuity. If the switch is in
place and the PDWA is off center you should measure near zero ohms between
the connector and ground.
I think the switch ground is the little nipple that goes into the PDWA
valve. Try measuring between that point and the connector on top.
- Hugh Fader
> -----Original Message-----
> From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net]On
> Behalf Of John Griffiths
> Sent: Sunday, September 15, 2002 2:16 PM
> To: 6pack@autox.team.net
> Subject: PDWA Plunger Continuity
>
>
> Hi Folks:
>
> I'm working on a '73 TR6. After restoring the wiring between my brake
> warning light and PDWA and grounding the connector and replacing the
> missing oil pressure switch (and eventually getting the
> wiring correct
> on that, thanks to Nelson Reidel et al)) I've been recently trying to
> reset the PDWA with no success. I tried the brake bleeding
> approach and
> I also tried the brad-awl-where-the-plunger-goes approach. No magic.
> The light stays bright no matter what I try. If I take the connector
> off the PDWA, the light glows dimly with the key on. Start
> the car and
> the light goes out. That, it seems to me, indicates that I have the
> connections OK. So... I took the PDWA plunger out and tested the
> continuity. I'm assuming it should show absolute continuity (zero
> resistance) at rest (i.e. plunger out) and infinite resistance
> (showing "1" on the meter) when depressed (or vice versa...). I find
> that it shows absolute continuity/zero resistance whether "at
> rest" or
> depressed. Also I find that if I plug the connector into the plunger
> unit (thereby connection the two points) the brake light stays on
> bright with key on and car running. Forgive the naive question but
> um... have I found my problem (replace the plunger switch)?
>
> Thanks.
>
> John
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