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Brake PDWA

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eldiabo

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After replacing a section of brake line I am now bleeding the lines. After getting all of the air out , the light is still on It seems the PDWA won't reset. The brake light did go dim at one point but then came back to full brightness Any ideas ? Thanks
 
Assuming the plug for the PDWA light is the splitter, it is likely that the splitter itself is dirty. The way it works is there is a shuttle inside that slides back and forth - if the pressure on one side disappears (failure) the opposite side's pressure pushes the shuttle over - triggering the light.

I suspect that you moved the shuttle while bleeding and it is now stuck. When I redid my brakes I belatedly cleaned out my splitter and it was amazingly dirty! You may need to take it apart to clean - or unplug the plug. :D which is what I did but not for that reason.
1749517739163.png

the shuttle is the black piece in the next pic. (and the article the pics came from is here

 

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The valve is supposed to block one end of the car off in the event of failure. It has tripped and will have to
be reset by hand.
Mad dog
 
mctriumph said:
The valve is supposed to block one end of the car off in the event of failure. It has tripped and will have to
be reset by hand.
Mad dog
Click to expand...
"Poolboy" has it. The very name of the item describes its only function. The Pressure Differential Warning Actuator is a relatively simple (if now archaic) device that ultimately trips a warning light if the pressure drops on either brake circuit. There's nothing within that device to "cut off" anything!
 
When bleeding TR brakes with a PDWA, you'll need to remove the PDWA sender (the plastic bit that screws into the top of the unit - the thing the wire attaches to) and then use a blunt object - like an old nail with the point filed down - to put down in the hole and manually recenter the shuttle. If you've rebuilt the PDWA, it should be easy. I highly recommend rebuilding the PDWA whenever you do major brake work. It will eventually start leaking on you - the seals on the shuttle will wear out and brake fluid will start coming out the top of the sender. I rebuilt the one on my 250 almost twenty years ago, and the seals have finally gone.
 
Whenever I have dealt with this I just open the opposite circuit at a bleeder and press the brake pedal until the shuttle centers itself. On my car I could hear it and feel it in the brake pedal. If you press too hard you will have to do the same with the other circuit to send it back the other way. It’s a bit of a nuisance but not too bad…
 
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