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MG Midget and Sprite Technical - Electrical Woes

After very few run outs this year due to lockdowns I managed get out last week before storing away for the winter. on checking the car I noticed N/S front side light not working, rear N/S light not working number plate lights not working, reversing lights not woking and window wipers not working. All bulbs and fuses are ok.
I Haven't driven at night or in the rain this year so I couldn't be sure if they failed individuality or all together, I've looked for melted wires which I can't seem to see. Any thoughts.
Rich65

Check the fuses and thoroughly clean all the electrical connections in the circuit, particularly the ones at the fuse box.
Chris Madge

Based on the limited information given, general advice, as Chris has put plus check all earths and switches (including their connections) all need to be clean, secure and protected.

The reversing lights and number plate light share same earth point in boot (on later sars anyway).

On later cars the combined front side light unit earths through its body.

I would get a long lead and connect one end securely to the battery earth post clamp and the other end to the (various) item(s) to get a clean secure earth. If they start to work then that's the problem or part of the problem as the live supply could still be poor but working - again as Chris put.

The relevant Driver's Handbook will tell you what fuses what and wiring circuits were when the car left the factory at least.

You always need the battery and all its cables and connections in good condition, the battery in good condition and fully charged to really be sure of sorting electrical (and starting) issues.

More info required if you're still having problems, god luck.
Nigel Atkins

Get a copy of the wiring diagram for your car, have it expanded at a copy shop, then have it laminated. I had my copy expanded three times its original size. Since it is laminated, you can use the dry erase markers to trace out the various wired and see if any of them have any common source points. If so, you use a test light to check for power at the common source point and either move "upstream" (towards the ignition switch/battery) or "downstream" (from the last point you had power in the direction of the light and its ground point.

For testing individual systems quickly, a test light having a wire with a ground clip on one end and a probe on the other end, with a light bulb in between, is a quick and easy way to test to see if power is present and get a rough idea of how much. (Light should shine brightly at full power and, if it does not, it indicates only a small power flow that needs to be followed up by testing with a volt-ohm meter.)

I have never been to Ireland. However, the last time my wife went over she noted the difference between the almost constant rain she had there compared to the dry desert we live in. Thus, I suspect that grounding problems due to rust formation around the ground points, may be a significant factor where you live vs where I do my trouble shooting. The test light quickly allows you to test for grounding faults and, if found, cleaning the ground and reassembly with some dielectric grease may help keep the grounds working longer.

Les
Les Bengtson

From that combination of failures I would strongly suspect a fuse. I find that the glass fuses can often fail, even though visually the wire through the middle looks ok. Sometimes its the fuse itself, and sometimes it is the contact of the fuse onto the spring clips in the fuse box that fails.

If you have a test meter its a very quick check to see that the downstream side of the fuse is in fact live.
If you don't have a meter then make up a test lead with wire and a spare bulb.

Advice to trace through using a wiring diagram, methodically cleaning all the connections and earth points is good. But if you are not familiar with the physical routing of cables and connectors it can be a bit daunting! I wouldn't argue against that, its well worth doing, but is a more pleasant task on a dry spring day than in mid winter!
GuyW

I think Chris has it with the fusebox as it's a common point for all, so the fuse posts and spade connectors need checking and cleaning.

Again assuming it's a later car with 4 post fuse box - I disconnect the battery and fully recharge it off the car whilst unscrewing the fusebox and checking it on its underside for contamination.

If removed completely for cleaning check it is refitted correctly with the linked fuses (for lights) correct way round.

Could it be that the brake lights are also not working?



Nigel Atkins

Yellow/red arrow - link in the (four) fusebox, to link supplies to lights (see your Driver's Handbook for details).



Nigel Atkins

Which model and year? 2 or 4 fuses?
Bill Bretherton

As Bill points out, we really need to know which model and year, as they do vary quite a lot.

It won’t be one fuse causing all the problems, as sidelights (when fused) do not share a fuse with ignition switched circuits, such as wipers and reverse lights.

Some models even had an in-line fuse for the wipers.
Dave O'Neill 2

I don't think it's one problem but on later models it could be the fusebox for all.

We really need to know if it's a red or green car.

Rich might have been on here before, but I'm not sure.

If he's not Rich might think Chris is the only reply, I can't remember but guess FB floods you with reply notifications so if you're used to that you'd be wanting for next response.

Nigel Atkins

If it's a 4 fuse, fusebox and has been fitted the wrong way round as Nigel points out, then I think the sidelights would only work with the ignition switched on, and then only down one side of the car.
Might be another clue?

But then I suppose other things would be wrong as well.
GuyW

TBH I wasn't thinking the fusebox was upside down just trying to prevent it if it's removed entirely.

If the car is to be stored over winter then it can be sorted now. To just get it working rather than get things fully sorted seems a waste of off-road time or opportunity depending on how you see partial year use of the car.

I also agree that bulbs and fuses need more than a visual look to confirm if they're working, which they might be.

I'd turn all electrical items on all at once, without the engine running, and see what is and isn't working and if anything interacts with something else (another reason for a full charged battery with it and all its main connections in good condition).
Nigel Atkins

I've looked at several Haynes wiring diagrams and sidelights are never fused, as I suspected (unless it's been modified.....). The faults seem un-related but, as the car hasn't been used much this year, it could just be that the bulb contacts need cleaning. Also, assuming the rear loom goes down the RHS then the rear number plate lights and N/S sidelight will feed off the same cable, so it could be a bullet connector in the boot. As for the wipers, maybe a bullet connector again or an earth. As said, you have to work through the wiring systematically to find where voltage or an earth is missing.
Bill Bretherton

The problem in a cold damp environment isn't just that it's unpleasant working on this sort of stuff ( unless the car is maybe in a snug CH garage!). But one could spend hours checking and cleaning all those terminals and bullet connections, only to find that if the cars isn't regularly used they could gradually corrode up and fail again in the remaining 3 months of winter. Maintaing the electrics in good working condition is one of the best side effects of regular winter driving!
GuyW

Bill,
Haynes might be alright for engine or gearbox rebuilds but I wouldn't know otherwise you use them as mug coasters or under uneven table legs.

The relevant Driver's Handbook will tell you what each fuse is for and include a wiring diagram (which I'd have blown up as Les suggested (to A3).

In the colour wiring diagram I put up earlier, if wired as per factory, fuse 1 is for one side lamp, one tail lamp, and one number-plate, so is fuse 2.

This gives illumination to rear if one fuse goes.

I noted Rich put number plate lights, plural, but that might have been a typo, or suggesting a later car, or replacement of unit from one to two bulbs, or one bulb had previously blown or not working or not tested this time - more info is required.

With these type of faults, and allowing for the green of Ireland including crud on contacts, I always think it's best to sort as much as possible from battery to end items as there's often more than one element (no pun intended) in the whole equation and prevention is better than future cure of other electrical issues. You don't have to strip the car down and do a full nut & bolt rebuild just check and sort one bit at a time. There's plenty of time with a winter lay up.


Nigel Atkins

Guy,
clean, secure - and protect, partly to prevent it happening again. Even if you do a quick clean up job it'll last more than 3 months and probably more than 3 years, it aint that dry in here in the Midlands (well East Anglia) and my car sits outside all year round, for 13 so far and I'm not cleaning up my electrics every so often and certainly not for the 'fun' of it.

I look to avoid as much work on the car as possible, if that means an hour or two repair whilst including preventative work or just doing preventative work I put up with that to avoid as much as possible future hassles, issues, repairs, breakdowns and any additional work on the car.

I can't understand how you and PaulH can possibly think I'd look to suggest doing unnecessary addition work on the car (well you perhaps to wind me up) I've obviously not make myself clear enough or repeated enough my views on this subject.

Obviously totally agree if the car was driven, if only occasionally, instead of being laid up things would be easier and better.
Nigel Atkins

The significant difference Nigel, is that you use your car regularly throughout the year. Every time you start up and drive and switch on, the current through those connections you have cleaned so well helps to keep them warmed up, dry and working.
GuyW

Unfortunately for a number of years now I've not used mine that regularly or frequently particularly over winters. Lots of condensation/damp where I am, particularly over winter. You can protect the actual metal contacts (internal), with your choice of protectorate, as well as protect exterior of the joint/contact.

Even so, as I do use my classic more frequently than most classic owners I am more used to doing simple manual checks rather than not remembering, or bothering, or relying on an idiot-light warnings. With lights and wiring in generally good condition it's easy to see from the driver's seat if most of them are working just by when it's dark and also looking for reflections or in the rear mirror, or even shop windows. Failing that I can walk round the car and look or if really, really desperate ask for glamorous assistant.

As I don't use them over much even when driving I might even test the horn, wipers and heater blower ad-hoc.

If any of this was difficult I'm not the type to be doing it.
Nigel Atkins

Nigel
We still don't know the car model and whether 2 fuses or 4. But the OP says the fuses are ok. Surely we have to assume that's true for now?

I think Haynes is ok. Obviously a forum like this is populated by people who know stuff about our cars in detail so that is better than Haynes. But the latter still has its uses. Yes, there are errors - for example, I used it for g/box rebuild and there's a glaring error ISTR but otherwise ok.
Bill Bretherton

Later cars definitely do have fused sidelights, split left and right. The number plate lights aren’t split, but connected to one side only.

If the fuse box is fitted upside down, the ignition is permanently on.
Dave O'Neill 2

Bill,
it's the lack of info that makes assumption even more dangerous, I'm with Guy that I've had bulbs and glass fuses that look fine to the naked eye but are still blown or faulty. I should have mentioned cleaning the end caps of the fuses too as well as the fuse holder springs.

Haynes is alright I suppose, for some repairs, but it's not so good for those that don't know details, like myself, as they may assume that it's correct where it isn't whereas with experience you learn some of its errors and omissions. Haynes for repairs relevant Driver's Handbook for more prevention with the all the information it contains.

I read the error you put as a glovebox rebuild and thought that'd be a big error on a Spridget!

Disconnecting the battery and doing basic checks, tests and cleaning (and repairs) on the basic electrics is easy otherwise I wouldn't be able to do it, but reading the Haynes to me doesn't help.
Nigel Atkins

Dave,
you do realise you are going against what's in the good book about the number plates lights being split, do I have to go out in the cold, remove a fuse and see how many number plate lights remain on? :)

Fancy putting that, on a Sunday too.

Nigel Atkins

Dave, thanks, I stand corrected. I've either mis-read the Haynes diagram or it's incorrect.

Nigel, have you been out in the cold yet? A waiting forum needs to know!
Bill Bretherton

Bill,
yes I have, but there's no moon so I can't see the black fusebox cover in the black dirt engine bay, and if I could I find it I wouldn't be able to see the fuses in the black fuse box as there's not enough light to reflect off the glass or shiny metal end caps of the fuses.

Best I wait until it snows to pick up on any reflected light then.

Also gives Dave the opportunity to apologies for doubting the 'good book'.

Of course I've no idea if my car is wired as from factory. :)

Nigel Atkins

Must admit, my '71 car only has the one wire feeding both number plate bulbs. So that is how I copied it for my Frogeye.
GuyW

Guy,
tut, tut, more customising/modding.

Frogeye only had one bulb anyway - see below from DH.

I don't have the Austin Sprite DH to hand - but - I took my 1980 Haynes from under the parrot's tray and it has two number plate bulbs on separate fuses for that period of car, be lighting a square number plate off the ends of the split bumpers and not the single light unit above oblong plate of earlier models IIRC.

Also aftermarket above number plate units could be with two bulbs even if they were supposed to be only one, that's what I put on my custom (AH) Sprite (Spridget) genuine original car.



Nigel Atkins

That's right. The frog just has a single wire.

My '71 car doesn't have rear bumpers. Or reversing lights. It's not supposed to be original!
That'll be why it also only has the single wire.
GuyW

But does the rear light have a single bulb or two?

Did you not also search for an Austin (not Healey) Sprite badge a number of years ago.

You should have updated your '74 Sprite with the later 1500 rear plate with those light units either side of the number plate, then you could have 4 bulbs on your no doubt black and silver plate - but according to the 1980 Haynes you'd be on two supplies (must return that book now as the parrot has nowhere to toilet without it.
Nigel Atkins

Nigel
I have a proper Frogeye WSM which tells me to use an asbestos pad when doing bodywork heat shrinking. Strangely, Haynes doesn't repeat that. Just sayin'!
Bill Bretherton

Two bulbs
No, I made my own Austin Sprite badge.
I didn't know they made a 74 Sprite Nigel. That must be super-rare
GuyW

Nigel, whadaya mean no moon? It's 85% full and light enough to read a newspaper (headline) here.
David Smith

Careful the DH isn't always accurate. The Frogeye DM shows a Smith's steadylift jack with a ratchet type handle. One has never been seen! Cars were equipped with a King Dick jack and an unusual ratchet (Horler and others) My number plate light has always had 2 bulbs so perhaps they could have been changed during the production of the car
Bob Beaumont

Bob, Excuse me if I'm being slow (!) but what is "DH" and "DM"?
Bill Bretherton

DH = drivers handbook, DM is a typo!! oops!
Bob Beaumont

Nigel

Indeed, Haynes shows number plate lights split. I obviously need to do some more revision.

Bill

Unfortunately, the wiring diagram doesn't show the 4-way fuse box as one unit, rather two pairs of two fuses, completely divorced from each other.

The 4-way fuse box was fitted from GAN5 onwards, but there was another (in-line) fuse added at the same time. There's a white/green from the ignition switch, which feeds the wipers and heater fan via the in-line fuse. Although the fuse is shown on the wiring diagrams, it isn't labelled on some of them.
Dave O'Neill 2

Sorry everyone I thought you could see my cars profile, its a 1973 Mk3 Gant5 with the round wheel arch. Its 4 fuse as you can see from image and two number plate lights one in each end of the bumper. Here we do have a lot of damp, humidity 90% plus. Metal does go rusty in my garage. It had a new wiring loom 20 years ago. Ive purchased a multi metre can I use this to check the fuses. sorry to sound stupid but electric is definitely my Achilles heel. After help online from Guy & Nigel the car was put back on the road 2 years ago and I have been driving problem free since then, though it was standing for 20 year prior to that and I have not touched any electrics.
Thanks






Rich65

PS I've managed to blow this up


Rich65

Hi Rich,
no problems in 2 years, you've the luck of the Irish.

To get your 'Vehicle profile' on view click the 'Customise' button at the top of this page, then on that page click 'Yes' to 'Display a link to a summary of my vehicles with my posts' then click 'Save option', Bob's yer Aunt.

Those colour diagrams are very useful but can have a very few minor errors - guess where my fusebox illustration came from.

Multimeters are alright but cheap digitals ones can be unreliable I've found, but usually good for continuity checks.

Easy way to check a bulb is to swap it in the other side that you know is working - but always swap back to make sure the working bulb and unit are still working, double check.

What is the green wire (above the double wire ignition wires) for?

How far have you got so far?
Nigel Atkins

Rich,
on your fusebox the double green and double purple connectors are slightly twisted, check the wires have some slack there and also that all (insulated spade) connectors to the fusebox are a good firm tight fit to the male spade connectors.

The fues are the modern type rather than original Lucas type so are a very slightly different size - check the fuses are all a good firm fit to the fusebox connectors and that the fuses are all 35 amp blow.

You're missing a spare fuse to the fusebox?





Nigel Atkins

DavidS,
either it was cloudy last night here or the dirt on the inside and outside of the window I look out was too thick as I couldn't see any moonlight - and we've yet to see snow here.

Guy,
the keyboard batteries were very low so it was combining some of its keys to save power, 1 and 4 for instance, but now fullpower has been restored.

Bob,
I will check the jack situation with Steve Gyles, another slur on the good book, I don't know, :shakinghead:.
Nigel Atkins

Rich

As others have said, it is a case of working back methodically from the end of the live feed at your duff componenet until you find the fault. Use a test lamp if you must, but I don't like working live, so I use continuity on a multimeter. Set the meter to ohms and work from there - don't use the bleep thing, it can be a red herring. Plenty of advice on the web - but basically as Les B. says earlier on. Colour coded wiring diagrams are a great help.
Oggers

Rich.
To recap.
A/ The front and rear sidelights, plus the number plate lights are all fed by red wires from the fusebox. I would have expected these to be paired so that 1 fuse serves front and rear nearside, and the other fuse served front and rear off-side. However the diagram you post seems to pair them so that one fuse serves the front and the other the rear. Whatever the diagram shows, or the handbook might display, they could have been wired either way so you could check this by removimg both the red wire fuses and then add each one back in turn and see which lights operate. Red wire items work with the ignition off (and on, of course!) Do make sure the fuses are well seated. Rotate them a little in their clips to make sure there is a good contact with the spring clips.

B/ The other 2 faulty items - reversing lights and wipers, are wired together from the green wired fuse 3 items. These only work with the ignition on. But from memory I think the heater and indicators are also off that fuse, so if it were a fuse problem, they also wouldn't be working. It perhaps suggests poor grounding issues for those, as others have said.


GuyW

....and of course - check the fuses are still OK. Personally I would just change all of them out anyways.
Oggers

It may just be the light but those spring clips dont look very clean to me. I've had that problem with the horn, fuse was ok and all looked good but ended up removing fuse cleaning the ends and the clips with emery and all worked fine.

Trev
T Mason

Ive not started yet, if I went into the garage on the Christmas holidays! you know the saying "happy wife happy life" But I will work through all the suggestions starting with fuses and connections and trace that green wire Nigel
Rich65

Guy, as I mentioned earlier, the wipers and heater fan should be on an in-line fuse, not off the fusebox, for GAN5 onwards. The fuse is located in the vicinity of the RH bonnet hinge.


Dave O'Neill 2

Yes Dave, my '71 car has the extra inline fuse as well. But I couldnt see it on the drawing that Rich posted for his car.
Perhaps that is where the other green wire from the upstream side of fuse 3 goes to.
GuyW

Well obviously Rich will have a relevant copy of the Driver's Handbook to refer to for fuses and wiring diagram.

If it's a 1973 car then it'll be on an alternator, as is my own fully concours factory original example.

In my combination reprint of the Driver's Handbook there's another diagram for 1973-74 but I don't know what the differences are to the 1973 diagram (not looked).

That extra green wire has factory look spade to it.

To save confusion and to relate to directly to Rich's car and fusebox wiring as it is now I've changed fusebox wiring diagram, added extra green wire and label fuses and their positions as A, B, C and D.

HTH






Nigel Atkins

Rich's wiring diagram isn't the factory version, so it's difficult to know how accurate it is - unless it was supplied with the wiring loom, perhaps?

Although the factory diagram shows six green wires coming off the fusebox - which they obviously don't - the non-factory diagram shows a number of brown wires connected directly to the battery, so there's quite a lot of inaccuracies in both, it would seem.
Dave O'Neill 2

Nigel

The 73-74 might include hazard warning lights.
Dave O'Neill 2

ETA: Looking at Rich's photo of his fuse box again, only that extra green wire looks to have factory type insulated spade, the others might be later replacements perhaps suggesting some work on the wiring. The fusebox also has hex head screws but that doesn't mean much.

I think all wiring diagrams should be treated with caution and as a guide rather than absolute as many changes (and errors or omissions) can crop up over the years and decades, even without allowing for previous owners knitting the wires and connections.


Dave,
I thought the hazards were just a bit after mine but certainly the 1973-74 diagram shows the hazard flasher unit and switch so another cigar to you.

Guy,
in the drawing Rich posted the in-line fuse is shown at the centre crease on far l/h/s, now I've found my copy it's a lot easier for me to see. As I put before there are a few minor errors on it as I think it's a transfer from USA wiring.
Nigel Atkins

Just an update, after switching wiper on and off several time they started to work I assume its a faulty switch.
The number plate lights its just the NS not working the OS is ok.
There are two inline fuses though the second inline fuse with the white wire going to battery is from the relay for the added driving lamps. see image.
Nigel, the extra green wire goes direct to the switch on the dash that works the window washer motor.
I have dug out an original dealers workshop manual with all the midget wiring diagrams though I have just noticed in the image it was printed in 1970 if its no good I have the reprinted handbook

P.S I'm going to try and digitise original dealers workshop manual for members providing i'm not breaching any copyright






Rich65

Rich,

I wouldn't assume your wiper switch is faulty, it, or the circuit, could just be suffering from lack of use which you resolved by switching on and off a few times. A few years ago I had the same symptom with my dip switch and this was solved by trying it a few times after which it started to work and it has been working ever since. HTH
Ray Rowsell

Yeah I'm with Ray
If you leave things unused the contacts get a bit dry/scaley You've got the switch going now give that n/plate globe a wriggle and start driving it
William Revit

I'm with Ray and Willy. Lack of useage is the problem I'll bet. Wiggle the bulbs, wiggle the switch and they'll likely come to life. Electrical contacts don't like being unused, especally in a cold, damp environment. Anywhere where there isn't a screwed, crimped or soldered connection is liable to go "open circuit" sometimes, including fuses and bullet connectors. I've had to "work" some of the old switches for the Frogeye restoration to get them working properly.
Bill Bretherton

<<"if the cars isn't regularly used they could gradually corrode up and fail again in the remaining 3 months of winter. Maintaing the electrics in good working condition is one of the best side effects of regular winter driving!">>
Although yet to be proved that is the precise fault of course. Contacts on glass fusses are also very susceptible to damp when unused for a while
GuyW

Rich,
I thought you might have a washer motor and that it was from the green wire but the factory spade meant it best not to assume.

As Ray has put switching the switch on and off about 10 times is the basic and easy way to clean the switch contacts (it may or may not be a short, medium or longer term solution).

Doing the same or testing is required for other infrequently items such as horn, (hazards), blower, wipers, flasher. Best done as part of or while actually using the car more regularly or if not with ignition off or possibly with battery disconnected.

Thanks for the offer of the WSM (Workshop Manual) but to save you time and get you more up to date there's already a PDF of the 1972 (12th edition) version available online. But you will still need to use the relevant DH (Driver's Handbook) of course for details of a 1973 car.
ALWAYS look at the DH first for information.
- http://www.spridgetguru.com/AKD4021_12thEd/AKD4021_12thEd.pdf

The number plate lights may be separately (A, B) fused to each other, see the wiring diagram in the relevant DH.

Quick fixes are fine to get you going but until you do the checks and sorts as I put earlier you could be repeating these quick fixes in the future and more than once.

Disconnect you battery, best to fully and slowly recharge out of the car, this gives you the opportunity to check the battery clamps, main leads, earths and if I was you the fusebox and all the connections suggested or as required.

This morning we took my neighbour to his car a few miles away as it wouldn't start for his wife, it was low battery, luckily he had thick jump leads in the boot. They'd forgotten what I'd told them two winters ago when the car wouldn't start in the garage.

I meant to put before I don't like the look of the double green wire connector, it might be fine but I'd give that a careful look and test.
Nigel Atkins

With many of our neighbours hardly using their cars this year, I currently have a round of 5 of them, putting their batteries on charge every 6 weeks or so. They are worried about their cars not starting when needed, should they have an urgent journey to make. All moderns.
GuyW

Guy

I use a terminal isolator on the MG and just disconnect or remove the in-line fuse for the bikes - seems to work well. Battery cannot drain away - although even so, I do charge them once or twice. I also tend to use Motobatt. Appreciate that on many moderns an isolator may involve re-setting a whole host of useless gizmos, but maybe worth considering for them for just 3 quid or so. Mind, many folk don't seem to know how to open the bonnet these days, so perhaps not...
Oggers

Thanks everyone for the help I’m going to go through everything electrical, working and non working. There are a few poor looking crimp connections under the dashboard that may cause problems in the future and I prefer a soldered one. Any thoughts on the solar trickle chargers
Rich65

Rich,
don't solder as it's not as good (que debate) and it's easier to crimp connections in situ behind the dash, it must be as I can do it.

Do yourself a big favour and buy yourself ratchet crimpers and auto wire strippers.

Also be aware that some insulated connectors are better than others and same with the (old style) bullets.

Do you really need a solar trickle charger, you could just disconnect the battery, or fit a dis-conect, or just leave it fully charged it should last for months unless you have some draw on it.

If you want more info on the crimping just email me or look in the Archives for the numerous threads and posts (many posts probably by me but also others' different views, opinions, advice).
Nigel Atkins

What debate?
GuyW

This thread was discussed between 26/12/2020 and 29/12/2020

MG Midget and Sprite Technical index

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