PDWA stands for: Probably Doesn't Work Anymore

[mjbeanie]

I am in a dilemma over this component and its troubleshooting. I could use some advice or suggestions.
Bled the brakes and they work well. However, Brake Fail light remains ON. I am certain its the PDWA (Pressure Differential Warning Actuator mis-positioned).

I followed the procedures in the manual, and on this forum. I went back to a rear wheel an bled it down multiple times, and the FAIL light never went off. So I went to the front, bled it down and the FAIL light never went off in this case either. My brakes seem to function well, but I don't know if I am only using one system. (?)

I don't believe this particular version has the "aperture for re-setting the pistons mechanically."

I am hoping for an alternate solution, or some insight on the procedure from someone who has successfully re-centered the internal piston in this unit, and cleared this fault.

(besides the obvious "fix" of disconnecting the light...lol)

Thanks guys
Mike

[Frogelan]

I know very little about the PDWA or the +2 but there are some useful videos on this subject on You Tube such as this one: https://www.youtube.com/watch?v=3qwqMHWT6Y0.

Is the part originally fitted a Girling RTC2525?

The video may contain some ideas worth exploring (changing the seals?) but others come to mind (the shuttle, the switch, the spring?) even if this is not the same model.

I hope this helps!

Andrew

PS: After drafting this, I stumbled across a Jaguar Forum on this subject.

This link seems to provide plenty of additional ideas: https://forums.jag-lovers.com/t/pdwa-in ... /408909/24

It is worth reading completely as it mentions an important aspect: how to bleed the system without upsetting the PDWA.

[mjbeanie]

Thanks for the response. The Jag forum did a nice job going through the troubleshooting. Looks like I'll need to break into the brake system. And remove and overhaul the valve. I was hoping to recenter it still installed but this seems unlikely. I disturbed it during the brake bleed and this does not appear to be reversible on-wing.
(Borrowed the term from my former life supporting Pratt and Whitney jet engines. lol)

[Frogelan]

If you read all of the threads, a recentering tool does exist and costs about 12€ + p&p + border costs.

It is probably wise in any case to change the O rings and the other master cylinder seals every five years anyway

As a result of reading the PDWA info, I have decided to include one on my project (which will have a diagonal split) so thank you for bringing up the subject!

I have bought one sight unseen (a brass MG midget version as I'm not keen on equipment that rusts) and will restore it.

Andrew