Welcome to our resource for MG Car Information.



TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph TR6 - PWDA switch

After my last question concerning Electrical Gremlins, I started checking the electrics, with some moderate success. I came across a missing part, the "P.W.D.A." plug, shown on page 404 of the Bentley Manual. I have the PDWA unit, and it is hooked up to the 4 brake pipes, but the electrical plug is missing. Neither Moss nor British Victoria show that part in their catalogs.

Obviously, the PDWA has something to do with the brakes, and I am guessing it must equalize the pressure or something to the 4 brakes. Does the fact that the electrical plug is missing mean that the unit is not functioning? Where kind I find the electrical plug, and if I find one, I'm guessing that one of the two leads will go to a positive and one to a negative.

And what happens if I can't find it?

Thanks, as usual. Dumb ass new TR6 owner John in South Florida.

Through the magic of Google, I figured out what it is and what it does. It basically monitors all 4 brakes and sets off the brake warning light if you have a loss of fluid, and therefore a pressure change, in your front or rear brakes. My switch is still there, but the electic plug for it isn't and I can't find one. Also, assuming I can find a plug, one lead goes to ground, and the other to power through the ignition switch, but how do I tell which one is which? There is a suspicious single loose wire near this thing that probably goes to one lead or the other, and I'm betting it has power. But, I don't know which one on the switch itself goes to power. Is it possible it wouldn't matter as the light, which I think is gone too, would go on either way? And do I need this thing hooked up electrically?

Before you go off thinking this is the cause of a "problem", you should know the function of this unit first.
The PWDA is "passive" in what it does. As you say it "warns" the driver if there is any "difference" in the "pressure" of the two hydraulic circuits (front and back brakes). It does not "equalize" the pressure in the circuits.
There should be a single wire from the harness to the "switch" mounted in the PWDA. This wire when grounded, iluminates the "brake" warning light on the dash.
There has been a lot of discussion regarding "workarounds" for this expensive piece, when one has a need to replace it. Some have even suggested removing it altogether, but I am not sure that is a good solution.
Check out the Buckeye Triumphs Website for a good article on the PWDA and its function.

Mark R.


Guess it might be helpful if i included the link

Mark R


My PDWA is also disconnected. When connected a large dash warning light shines brightly. The warning circuit also involves the oil pressure sensor. Originally either issue (low oil pressure or unbalanced brake fluid pressure) would light the warning light.

Based on what I've read, improper bleeding of the brakes may cause the PDWA piston to be displaced, generating an erroneous warning. I figure my PO &/or his tractor mechanic disconnected the wire after bleeding the brakes improperly.

When I rebuild the brake master cylinder I plan to give the PDWA a chance to work properly. If it leaks I'll make a decision on my next move. The Buckeye site should provide you what you need.

EC Smith

I rebuilt my master cylinder and pdwa this past winter twice duoh. My pdwa does not work at all the electrical connector is bad my brakes work as good as new. If you take apart your pdwa make sure you pay close attention to the washer's, I rebuilt mine twice trying to find a leak that turned out to be a very small washer under the elec. connector all fluid in the reservoir would drain overnight, good thing it was silicone. If you check the archives on this you will find that the elec. connector is no longer sold but I think a ford f-150 older model matches up right. I won't sweat mine as it seems to be functioning properly. IE I could bleed both ends and both sides of the car.

This thread was discussed on 15/09/2003

Triumph TR6 index