MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Newbie with Unstopable wipers


Dear All

I have just bought my first midget (1978 1500)and had it 2 weeks,
I have sorted out the ignition system, rebuilt and balanced the carbs and rehung the exhaust which the previuos owner had bolted directly to the car....
Car runs well now, but yesterday I switched on the wipers and then could not switch them off!
I have been through the archieve and think that this is a problem with the parking switch.
If so, is it located inside or outside of the wiper motor? is it likely to be fixable or is it a case of replacing it?
Any advice please.

Jon
J Warren

GMorning Jon,

The parking switch clips into the body of the wiper motor. I think the later models, like yours, had a two speed motor, but I don't belive this changes the parking switch configuration.

Moss stock them at about 15 quid, but they are quite reiable in my experrience;

Item 38, http://www.moss-europe.com/Shop/ViewProducts.aspx?PlateIndexID=1367

I'd check the dashboard switch is isolating the power before pulling the wiper motor.

M
Mark '74 Midget


Hi Mark

Thanks for the reply.
How do i check the switch?
Basically wipers will stop if I pull the brown green wire off the back of the dash switch which I believe is the park circuit , it appears to be constantly live.

Jon
J Warren

Jon,
Have you disconnected and re-connected the dashboard switch terminals? I think there should be an input and 2 outputs from the switch, and you may have reversed the two output wires.

Guy
Guy Weller

Hi,

My cars an earlier model, my park (live) wire is Green/Pink, switched using the auxillary feed from the ignition. Your park (live) wire I belive is Green.

You should have two feeds from the dash switch, brown.red and brown.green, these are the two speed feeds that connect to the brushes via the parking switch. The fourth wire is brown (earth).

Check that your brown.red and brown.green are not live when the dashboard switch is off. If they are live then investigate the dash switch.

Picture of the switch,it clips into the gearbox. Earlier switches were screwed in, I think you need to pull the motor/gear out if this earlier switch is fitted.

Mark




Mark '74 Midget

Wipers that don't stop: I had the same problem very recently on my 1976 1500 Midget (mine is a single speed system but the basic principle of operation is the same for twin-speed motors).

J Warren - when you say your wipers stop "when removing the brown/green wire from your dashboard switch" (assuming your ignition is 'on'), do the wipers self park in their correct 'at rest' position, or do they stop at any position on the windscreen?

If the wipers self park correctly, then, for your symptom of 'unstoppable wipers', you have a faulty dashboard switch (ie the switch isn't interrupting the current to the wiper motor when the switch is operated to 'off'). (NB Bear in mind that you could also have an intermittently functioning self-park switch (it is clipped to the body of the wiper motor).

Assuming the ignition is still 'on' . . . . if the wipers do not self park correctly (ie they stop at any position on the windscreen at the moment the dashboard switch brown/green wire is disconnected) then it's a 99% certainty you have a faulty/intermittent self-park switch (which is clipped onto the wiper motor body)or you have a faulty ignition-controlled-live-feed wire feeding the self-park switch.

How it works:

The wiper motor has connected to it an 'ignition-controlled-live-feed-wire' that is always live with 12volts (via fuse #2 in the fuse box) for as long as the ignition switch is 'on'. This feed is not controlled by the dashboard wiper switch - the wire colour is green.

As well as a black (chassis) wire, the wiper motor also has either one (single speed)or two (dual speed) wires coming from the wiper dash switch to the motor - these wires are coloured brown/green and/or red/green. Obviously these wires give the motor its on/off volts from the dashboard switch.

The motor's self-park function uses the voltage from the 'always on' green wire. If the driver operates the dashboard switch when the wipers are in 'mid-windscreen' position, then the self-park switch detects the incorrect position of the wipers and uses the 'always on' green wire feed to continue motor action until the wiper blades are at their correct rest position.

------------------------------------------------------

In my case, my self-park switch had worn resulting in its contacts not opening when the wipers were in their correct rest position - the wipers just kept on wiping irrespective of my dashboard switch position. This could be your problem, but from your description of 'removing the brown/green dash switch wire' resulting in stopped wipers, it doesn't sound to be the case.

I hope this helps.

PS
If you find that you have a faulty self-park switch, then you will have to totally remove the wiper-motor from the car. It's a bit of a 'bar steward' job. In-situ you will have to remove the motor's two strap bolts and the (four or five) small screws holding on the motor's cover plate. Once the plate is removed, you will have to remove the circlip holding the wiper rack's inner cable to the circular drive cog. Careful the circlip doesn't disappear down inside the front wing! You will then be able to remove the motor and set about replacing the self-park switch.








Andy Hock


Guys, thanks for all the excellent advice.
My wipers are single speed (or at least wired that way)

Andy if I remove the brown green wire from the switch the wiper will stop, they will not park, if the brown green wire is left connected once the wipers are switched on they will not turn off again unless the brown green wire is diconnected or the ignition is switched off.

So the park switch in the motor is prime suspect then!
Jon
J Warren

JW writes>> single speed, at least wired that way
-----------------------------------
AH replies>> Ummm . . . . when you say 'wired that way', do you mean they were originally two-speed? The reason I ask is that it's beginning to sound like you have a wiring configuration problem around the dashboard switch (as suggested earlier by Guy Weller), possibly as well as a faulty self-park switch!
Andy Hock

Hi Jon,

My post was corrected by Andy, the two speed wires from the dash switch are coded brown.green red.green and not as I posted. urrrg.

If your brown.green is constantly live, as you say, then the dash switch needs investigating. This should not be live withthe switch in the off position.

It looks like you may have two problems here, as even when you remove the power the wipers should still park.

Andy, my self-parking switch removes fairly easily without removing the motor, but that maybe because it is the later 'clip in' switch. You do need a mirror to get in back in though!.



M



Mark '74 Midget

Hi Jon, I'm over in South Shields. I've got a 77 midget in the garage out of action, if you want to borrow the switch to test.

Simon.
S McGregor


Again thanks for the advice, Simon thanks I may well take up your kind offer.I'm at Whitburn.
I would like to point out that the wipers worked fine and parked until yesterday afternoon so I don'think the wiring is fundamentally wrong. The dash switch is wired as per the factory wiring diagram . I will get out there with a multimeter after work.

Jon
J Warren

What an excellent post by Andy Hock. Nice one Andy.
Robert (Bob) Midget Turbo

Thanks for your kind words, Bob. As I say, I recently replaced my faulty self-park switch, so the detail of the work is still fresh in my mind.

J Warren - as you report that everything was fine with your wipers until yesterday, I would take a guess and say that your self-park switch is at fault - they do wear out and suddenly fail. But, given that, I still can't explain why your dash switch is performing as you report irrespective of any failure doubt in the self-park switch.

Andy Hock


Well, all is now well.
I checked the wiring, unpluged the connector block at the at the motor, tried it. Wipers now switching on and off and parking correctly.
I reckon I have an intermittant parking switch fault.
Watch this space for updates!
Thanks for all the help
Jon
J Warren


Update.
Unstopable wipers returned today.
Self park switch intermitent I think.
Brown green diconnected for now and timing when to turn them off!

I will investigate further in the coming weeks, need to sort out the dashlights etc as no light to speedo or rev counter at the moment. Lens on oil warning light in speedo also dislodged and needs sorting. Hours of fun.

Jon
Jon Warren

This thread was discussed between 22/07/2009 and 24/07/2009

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.