PDWA switch

[Andes]

Hi all, my PDWA is giving me a headache and i'm not sure what to do next. I replaced the seals and bled the system last year, managing to centre the shuttle and extinguish the brake warning light. However, for some reason the light has decided to illuminate again. So i've tried bleeding the brakes again but i'm yet to hear that re-assuring clunk when the shuttle centres itself and the warning light goes out. Any ideas (apart from removing the bulb) appreciated

[greystag]

Take the switch out,you will not lose any fluid, now use a small mirror and a torch to look in the hole left by switch you will see a v if not it has gone left or right ,use small sharp screwdriver or scribe to move it to middle. good luck. IF the v is in middle, you have an issue with the light or switch. the light eliminates when switch goes to ground or earth.good luck Terry

[Ian P]

I overhauled mine last year but every now and then light would come on and I know the plunger was aligned, although it felt like a good connection and I had give the terminals a good clean it turned out I had to give the terminals a squeeze together to make good contact
Ian

[Sarge66]

I had a similar problem a while ago. It turned out that the oil pressure switch wire had somehow become disconnected. As the PDA and oil pressure switch are interconnected simply reconnecting the wire solved the problem.

[StagJonno]

I had a similar problem a while ago. It turned out that the oil pressure switch wire had somehow become disconnected. As the PDA and oil pressure switch are interconnected simply reconnecting the wire solved the problem.

Think this wiring arrangement is for Mk1. On Mk2, the H'Brake and PDWA warning light circuits are effectively in parallel with no involvement of the Oil Press circuit.

Jonno

[Andes]

Cheers guys, thanks for the great response........is it that easy to manipulate the shuttle, do I not need to bleed the brakes at the same time to allow the shuttle to move (to simulate fluid loss)???
Regarding the switch, I did wonder if the plunger had developed a fault and was now sticking out too far and activating the light, but I can’t find my old one (which was faulty and covered in brake fluid) to compare it to........
Btw, it is a mk2 and connected to the handbrake rather than the oil light.

[Sarge66]

Hi Jonno

I can assure you that my car is a MK2 and that the brake warning light is farther both by the PDA and the oil pressure switch as described in the manual. A fault on either circuit will cause the light to glow.

Hope this is helpful.

Noel

[MandM]

Make yourself one of these to hold the shuttle central while you bleed the brakes, may be you still had some air in the system that made the shuttle move and illuminate your light?

P1060689.JPG

[StagJonno]

Hi Jonno

I can assure you that my car is a MK2 and that the brake warning light is farther both by the PDA and the oil pressure switch as described in the manual. A fault on either circuit will cause the light to glow.

Hope this is helpful.

Noel

Not sure what manual you're looking at - Mk2 are shown on the wiring diagram (ROM, Haynes and a large scale colour version) for Commission No LD20001 on, with the H'brake & PDWA operating together. This is how they're connected on my '76 manufactured car. Either the PDWA or H'brake on lights both warning lights - complete duplication. There have been many stories about the transition from Mk1 to Mk2 not being clean, as it's understood that the Mk1 parts bins were emptied and used on early Mk2s.

Jonno

[Andes]

Cheers MandM, I don’t know if it’s because I’m using the phone app but the picture of the tool you suggested is not being displayed.......
Andy

[DJT]

Try this. I made the tool from an old cylinder head stud many moons ago:

[Sarge66]

Hi Jonno

I have copied the wiring diagram that I used to solve my problem referred to in my earlier post and the digram is shown below. I offer this information not as a Stag expert (still learning) but in the hope that it may help others. As you will see it clearly show the interconnection of the oil pressure switch and the PDWA. The manual I referred to is Publication Part Number 545162 and further details are contained in section 70.

Noel

[Sarge66]

Diagram referred to in my earlier post.

Noel PDWA:OPS.pdf

[StagJonno]

Diagram referred to in my earlier post.

Noel [ATTACH]n757203[/ATTACH]

Yes, you're correct - just checked the pdf I have of the ROM (published in 1973, so not perhaps catching the changes to the Mk2) and that's the only diagram in there. I apologise for mistakenly indicating otherwise. The Haynes manual shows this arrangement too, but only for up to Commission LD20000. They also show the parallel arrangement for LD20001 on. Copy of part of my attached colour diagram shows this.

Bottom line - if the PDWA light comes on with the handbrake - it's as for LD20001 on. Otherwise, it's likely to be for up to LD20000, or is part of the transitionary production.

Jonno

[mopoole]

Jonno,
That looks a good wiring diagram with all the colours easily seen (eyes aren't what they used to be). Where did you get it?
Regards
Maurice