PV wipers

[Salop Farmer]

I was wondering if anyone could help solving an issue that has suddenly developed with my12v PV 544 wipers. They were parking perfectly ( at the quarter to position) but yesterday while out on a run in light rain they decided to start parking at the 10 to position when switched off on the dash! It is as if they commence the next sweep of the screen before they stop. I really dread having to extract the whole mechanism from under the dash to solve the problem! Any help will be very welcome.

[Ron Kwas]

SF;

Your description of "It is as if they commence the next sweep of the screen before they stop.", is what I would call "late Parking" (after they ideally should have stopped!)...since we know the 544 Wiper Motor should stop by way of Dynamic Braking (Reference: https://www.sw-em.com/544%20Wiper%20...ion_with_Dy_Br ), it sounds to me like the DyBr is not functioning, and the motor is stopping because it simply runs out of power (after power is removed and not DyBr!).

Remember, stopping by means of DyBr is a two step process:
1. Power is removed, and
2. Armature is shorted to chassis, immediately stopping the coast-down, and halting it is a precise park position.

...so it sounds to me like the motor is stopping only due to 1.

I expect there exists a problem with the chassis connection which is used for DyBr...this could be withing the Park Switch internal to Motor Assembly, but before extracting the assy to inspect internals, I suggest you check that the chassis connection to term 31 of Wiper Switch is present, and that switch routes this through to term 31 of Motor Assy when OFF (these are continuity checks with Ign OFF, but could also be performed as V-checks during operation. V at term 31b of Motor Assy must be 0 as soon as W Switch is placed in the OFF position, and then 53 at the desired park position.). Please report findings!

Good Hunting!

[Salop Farmer]

Thank you Ron for your comprehensive reply to my wiper issue. I think you are right the motor is probably coasting to a stop rather than being braked as you describe. I will make the checks you suggest and report back. Again, many thanks.

[Salop Farmer]

Sorry it took me so long to reply Ron but other jobs have taken priority over the wiper issue. As you suspected a bad earth at terminal 31 was the culprit. All good now thank you.