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MG Midget and Sprite Technical - Dash Indicator Problem

Hi,

I have given up trying to fault find the issue with my dashboard indicator lights and seek help here.

Having wired up the new loom I connected the original flasher unit.

Both front and rear indicators worked, but the dash indicators didn't.

I bought a new flasher unit, and yes a very cheap one. But this didn't change anything.

I've checked the wiring so many times I am sure it is all correct as everything else electrical works perfectly.

However tonight I did notice that the dash indicator lights do actually work, but the glow is so faint you can hardly see it.

I swapped over to the original flasher and both dash indicators stopped working, so I put the new flash back and again a very, very faint flash.

I was wondering if I should invest in a new more expensive flasher unit or could there be something else causing the reduction in brightness.

Any advise would be very welcome as this is the only electrical gremlin left.

Many thanks

James

James Paul

I wonder if the bulb holders are earthing. You could try taking a spare length of wire and connecting a temporary earth to a good place on the body.
Mike Howlett

Hi Mike,

Thanks for replying.

I’ve wondered if it was an earthing issue.

I’m a little unsure how to test it as you have suggested.

I’ve just tried a spare wire from each green wire going to the bulb holder and earthing it, but sadly there is no difference. I could feel a click on the earthing wire every pulse from the flasher unit. But the bulbs are still really dim.

I can’t see any earthing points I’ve missed from the wiring diagram.

So frustrating!




James Paul

To be certain of a good earth do a temporary wire from the battery earth post to whatever needs the earth.

I had a twin wire long enough to go from the battery in situ to the furthest part of the car, both ends had crimped connectors so that different connector tail leads could be used at all four connections. One end would normally have crocodile clip or clips tail connectors to take direct power and/or return to the battery. The other end whatever connector(s) required. With lights you could also see full brightness, bypassing the car's connections at bullets, connections and switches.

Nigel Atkins

James, the earthing for those bulbs is via the little claw fingers of the bulb holder making a good electrical contact with the metal of the dashboard. If the dashboard has been repainted or something else like rust has developed around the hole this could be blocking a good earth connection.
What Mike is suggesting is attracting a new wire between the metal bulb holder and a body earth point. (not between the green wire and earth)
GuyW

Hi,

Guy why are the little claw fingers held in place with a plastic cover? That in itself is isolating it from any of the bulb parts, isn't it?

On the other dash bulbs for the instruments for example I've noticed they won't work at all unless earthed. But these seem to be different.

I did try earthing the clips but still only a very, very dim light.

The earth for the indicator stalk is working well as the main indicators, flash main beam are all fine.

This is a brand new loom from auto sparks. I've also just looked at the old loom and the clips are isolated.

I've also just cut out the old dash indicator holders and wired them in and same problem.

So it must either be an problem with the flasher unit or something on the indicator stalk.



James Paul

Hi James,

You could try connecting the P terminal on the flasher unit to one side of a bulb and the other to a good earth. If the bulb flashes along with the indicators you problem is with the warning lamps. As others have suggested it will probably be an earthing issue. Do the lamps in the gauges work when the side lamps are switched on. If They don't or are dim the dash panel itself is not earthing.

Good luck

Jan T
J Targosz

James
There are two wires to each bulb - it might be that, in the case of your loom, one of them is earth so check continuity from appropriate bulb holder contact to a good earth point. It may be that the two earth wires (from the two bulb holders) are connected together but not earthing properly.
Bill Bretherton

Hi Jan,

That is a good suggestion on the bulb to the flasher unit direct.

I'll try that now.

All of the other lights on the car including dash work fine.

Hi Bill,

If the dash wasn't getting a good earth then none of the dash lights would work.

I'll check the black earth again from the indicator stalk to the speedo but as I said the speedo light works fine, as do the front and rear indicator lights.

thanks for all the advice, it is appreciated.
James Paul

Are you sure that the bulbs are dim?
I had a similar problem and found that it was simply the green filter discs in front of the bulbs on the dash were so aged and sooted up that they were virtually opaque.

I ended up replacing the filter discs with some acetate discs cut from a green tinted A4 stationary folder.
I had to use several layers as otherwise the green light was too bright at night.
J Smith

Zooming in I see these are two wire bulbs, not a single wire as I thought, so the holders may not need to be earthed after all.

As far as I can make out, one has a green plus a green with white stripe, and the other has a green, plus a green with blue stripe. Have you got the single colour wire and the striped wires connected to their correct bullet connections at the loom? And, I assume the bulbs are the correct ones?
GuyW

James
I was referring to where the two earth wires actually connect into the loom - you need to ensure this is a true earth point.
Bill Bretherton

Looking at the pdf diagrame, neither is an earth wire.
I suspect you have one pair of wires crossed over at the first bullet connectors.
GuyW

Hi,

So I have just tested the new flasher unit, by connecting one of the old dash indicators, I cut out from my old loom, directly to the new flasher unit. Had one wire on the P terminal and the earthed the other...

...just a very, very faint dim flash.

I repeated the test with the old flasher unit and nothing at all.

I'm going to buy a more expensive flasher unit and see if that fixes the problem.

As I said in my first post the new one was very cheap.
James Paul

How interesting. My experience is with the MGB and on the ones I have owned the warning bulbs have to be earthed through the holder. But on the very early MGB the circuit is the same as in the PDF shown above. I can't figure out how it works. Over complicated methinks.
Mike Howlett

James,

If you connect the indicator wire attached to the P terminal to 12V instead does the bulb illuminate properly when installed and earthed. I assume this is the earlier hot wire type flasher.
David Billington

Mike, As I Understand it works by the second set of contacts (for the dash light) within the indicator switch, which it puts the respective L/R wire to earth when you use the switch.

Yes over complex - probably why they simplied it on later models.

R.
richard b

Looking at the pdf in more detail, the bulbs do not earth directly, but via the P terminal on the flasher unit. The two bulbs are alternatively fed with 12v via the stalk switch and then returned to earth (body) via the P connector. So Guy is right.

Check for continuity, with an ohmmeter, between P terminal and one of the terminals in each bulb holder. Also check that the flasher unit is making good electrical contact with the body, in fact do that first as that contact is essential.
Bill Bretherton

ETA: My apologies, I now think Richard is correct and the flasher switch alternately earths the bulbs - the pdf is unclear, but that would make sense thinking how the 3 terminal thermal flasher units work.
Bill Bretherton

I've probably got this all wrong, but if the 2 wires to one bulb were deapped over at the bullet connectors wouldn't that effectively put the two bulbs in series doubling their total resistance, reducing the current and causing them to light only dimly?
I am not an electrician!
GuyW

Having looked at the schematic it seems to me to be wired as shown here http://www.nsu4.nl/english/e1flasherunit.html which is why I suggested trying the wire connected to P to 12V. Following the schematic the other side of the indicator is connected to ground although the path is a bit circuitous.
David Billington

James,
Have you looked at the green filter discs in front of the dashboard indicator bulbs as J.Smith mentions? I had a similar problem on my 72 midget and found the filter discs were coated in dust.
Simon
S Holt

See Item 14 in attached image

AHH6334 - INDICATOR WARNING LIGHT WINDOW NLA

Simon


S Holt

Simon,

I had that problem some years back on my frogeye and managed to find an indicator unit from an electronics supplier that was close enough only an expert would likely know it wasn't original.
David Billington

The plastic of plastic milk bottle screw caps (semi-skimmed) are just the right translucency for cutting new green lens covers from. On my '71 car, which has a left and a right lamp I use red for port (fully skimmed) and green for starboard (semi skmmed) !
GuyW

Guy,

Around here they stopped using green plastic for the top on the semi-skimmed I buy in Sainsbury's a few months ago, they're now just natural translucent so you better keep a stock while available..
David Billington

Same here David, although a bit variable as the coloured ones do keep reappearing. But I have a few spares on bottles used for germinating seeds in the greenhouse. Not that indicator lenses wear out particularly fast! 20 years ago I even posted some to someone in the States, needed for the same purpose. Apparently they didn't supply their milk in plastic bottles like ours.
GuyW

Guy,
I like it, port and starboard indicators:)
Simon
S Holt

Hi,

Thanks again for all your advise.

I know the green filter isn't dirty because I had to fix mine. The rubbers were totally gone, so I found these rubber blanking end caps on ebay which fit over the red cardboard cylinder. They needed a little trimming to fit on the bulb holder, but a good replacement I thought.

Also bought a sheet of green heat resistant acetate for a couple of pounds of ebay.

I thought if it wasn't dark enough I could cut another section out and put them together.

So I know it it has to be either the earthing or the flasher unit.

I've double check the earth all the way up to the indicator stalk and that seems to be fine.

I tried the test that Jan suggested and it is still flashing very dimly.

So I'm going to buy a new flasher unit, this time the more expensive lucas version and see if that fixes it.

If it doesn't then...






James Paul

Beware modern Lucas. They may be in Lucas boxes but they are mostly the cheap junk made abroad, same as other bits. I don't worry about whether the unit looks the same as the original and I use an electronic unit. The advantage is constant rate flashing even when the battery is low, and much lower current drain.
Mike Howlett

If you're going to splash out on a new flasher unit why not go LED? The LEDs are much brighter, even visible on a bright, sunny day (remember those?).
Classic Car LEDs do a unit for about £9 IIRC and the bulbs are a couple of pounds.

https://www.classiccarleds.co.uk/collections/switch-warning-light-bulbs
Jeremy MkIII

Hi Mike,

I think the electronic ones only work with negative earths, but thanks.

and thanks Jeremy, I've ordered a couple of led bulbs to try out.
James Paul

James you'll need an LED (flasher) unit (if you don't have one already) to make the LEDs work. The LEDs don't draw enough current to 'heat up' the traditional unit sufficiently to make it work.
Jeremy MkIII

Hi Jeremy,

Yes sorry, not for the flasher, just the instrument lights.
James Paul

James,I have LED indicators on my positive earth frogeye. You have to specify when you buy them.

And they are two- colour ones on the front so they show white for the sidelights, but flash a strong orange under the clear lenses for the indicators.
GuyW

Hi Guy,

ok thanks where did you get them from?

James Paul

James
Have you tried David's test I.e. connecting 12v to the lead that connects to the P terminal? That test will verify if the bulbs are bright enough. If still dim there's resistance somewhere between P and where the wire splits (under the dash I presume) to feed the 2 bulbs.

If the bulbs are now bright then the fault must be in the flasher unit. You do have the correct rated flasher bulbs (front and rear of car) I presume? That's important with thermal type flasher unit.
Bill Bretherton

Hi Bill,

Yes I tested it during the week and nothing. Also Richard came over this afternoon and we tested it again and came to the conclusion that the flasher unit has had it.

I'll be ordering a new one next week.

Thanks for all your help!
James Paul

James, I got mine from these people:
https://www.dynamoregulatorconversions.com/tips-and-hints-when-fitting-leds.php

Its a bit of a chaotic and crazy web site to navigate but the products are good and when I got mine they were competitively priced, Although by now they may have been undercut by imported junk.
GuyW

thanks Guy!
James Paul

James
Do you mean that you disconnected the wire from the P terminal, then connected the wire to a 12v source and bulbs didn't light (with indicator stalk alternatively switched to left and right?
Bill Bretherton

Hi Bill,

The flasher unit has had it. Nothing wrong with the earthing or wiring.

Thanks
James Paul

This still seems odd to me. The flasher unit should be a simple make & break contact. So if it makes contact then current flows, there's no half way with this. Plus, if I understand correctly, the actual indicators work fine, its just the dash tell-tales that are dim. If there's enough current to work the indicators, then why not the dashboard lamps unless there's a wiring fault.
GuyW

Guy,

The flashers have 2 contacts, 1 for the main indicators and 1 for the dash indicators so the dash indicator one could be bad. Might be corrosion in the bulb holder. Still haven't seen the question answered about whether the dash indicators glow properly when connected to 12V.
David Billington

Ah, thanks David.
I guess then that P on the flasher unit stands for Panel.
GuyW

According to the page I linked to earlier in the thread it's for 'pilot' lamp.
David Billington

I went to see Paul’s car and he’s making a rather nice job of the rebuild !!

We only tested the two flasher units by installing into the car connecting power and load which produced a good flashing set of indicators. I had a test lead with a single 2.2 w bulb which we connected to the P terminal and tried a few earth points - nothing- so assume both blown/faulty.

So when he gets a new flasher we agreed that he should repeat that exercise (single bulb to earth from P terminal) to prove the flasher unit AOK.

A test of the loom wiring back from the P connector is still required to determine if a problem exists down stream - possibly even the stalk switch which does the earthing to make the panel circuit.
Hope James doesn’t mind me responding !
R.
richard b

Hi,

New flasher unit arrived this morning and it worked first time.

Also ordered a couple of LEDs and I really like the result. Two more ordered for the other two gauges.

Just wish I had paid a bit more for the new flasher unit first time round!

Cheap rubbish!

Thanks for all your help.

James





James Paul

Thanks for the update James, glad all is well now. The pilot light contacts must have been worn/ dirty in the old flasher unit.

Those LED panel lights look impressive - I might get some!
Bill Bretherton

Good news James ! getting there now, soon be on the road!

I don't like bright dash lighting - distracts my eyes - my SAAB has a 'night panel switch' which cuts all dash lighting except the speedo - probably left over from a fighter plane !

R.
richard b

I might feel different when I get to drive it in the dark, so I’ll hold on to the old bulbs.

Thanks
James Paul

One of the best drives is on a summer's night, top down, empty moorland roads, all dashboard lights off (including speedometer) drive by the stars and just the sound of the engine.
GuyW

It might just be the photo but you should put the same colour LED as the lens so green behind green (red behind red etc.).

For the gauges you could have bright white or more traditional look warm white or go posh and have Vanden Plas green tint with green LED bulbs or not for me deep blue light, all on the link Jeremy's link. - https://www.classiccarleds.co.uk/collections/switch-warning-light-bulbs
Nigel Atkins

My original Frog dash lights were almost like having no lights at all. I switched to LEDs and now I can actually read the gauges. And with that little switch under the dash I can always turn them off. I didn't change the indicator light since it's always been bright enough but I've gone to LEDs for the headlights and tail/brake lights. And I've gone through a number of flasher units before I got one that worked properly for more than a few weeks.
Martin

To buck the trend, I've got glow worms in the gauges as they're bright enough at night and LEDs in the indicator repeaters as you can see them even in bright sunlight to compensate for the 52 year old self cancelling mechanism not always self cancelling🤨.
Jeremy MkIII

This thread was discussed between 11/01/2023 and 17/01/2023

MG Midget and Sprite Technical index

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