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MG Midget and Sprite Technical - Midget brake light switch feed

This will hopefully be an easy one for the Illuminati out there: 1978 midget wiring loom, does anyone know where the feed for the brake light switch comes from please?
I recently bought the car,after a full resto, and have since been fettling a few bits and pieces. The brake lights have never worked since I got it, I thought switch or bulbs but no, all good there. However doing a bit of bulb and lead testing last night and it turns out that both wires to brake light switch go to earth, although I know not where. Clearly one of them should be live but where does that feed come from please. Loom looks in good order and no fuses blown. Everything else works. The wiring loom diagrams avaialble on line are two small for my paltry eyes. I could take a new feed straight from the fusebox but I'd rather keep things standardish if its an easy fix. Thanks muchly all. Jon Ryden. Lincoln.
JE RYDEN

Jon,

My Haynes manual indicates there should be a green wire going from the brake switch to point 6 on the fuse box and a green wire with purple trace going to the brake lights the other side of which will be earthed.
David Billington

Jon,
if you get yourself a (reprint) of the Driver's Handbook it will tell you all about your Midget (and include wiring diagrams, though they are on small pages).

The green wires David refers to are the live wires, the earths are the lamp clusters themselves to the body of the car which is the earth that returns to the negative battery post via an earth lead(s).

The green wire comes off the fusebox to give power to the switch when operated, which in turn powers the brake lights (one filament of the combined rear/brake bulbs).

You can test if the switch is faulty by bypassing it by joining the the green and green/purple wire connectors together and switching the ignition on, the brake lights should illuminate as they have an unswitched live supply from the green wire off the fusebox.

Photos are of the contents page of an earlier model of Midget, but it will give you and idea of the comprehensive nature of this great booklet, and a sample page from the 1500.

1500 DH - Ref: 0058 here - https://mgownersclubstore.co.uk/catalog/Online_Catalogue_Handbooks_5.html






Nigel Atkins

Thanks David, thanks Nigel, that's great information. Best regards, Jon Ryden.
JE RYDEN

Ah, forgot to add, sorry, the feed definitely doesn't come from point 6 on the fuses on this car.... and it looks like a standard loom. There is however a "mystery item" on the other side of the engine bay to the fuses, a brake fail sensor or similar, it has wires and brake pipes going to it (I cant recall the correct term since I googled it). I think the feed perhaps comes from this on mine, I'll have a look at the weekend, no worries. Flipping old cars.
JE RYDEN

Jon,
is yours a UK car or other?

(Cooling system photo in my previous post is for (earlier) Midget 1500 from DH.
Nigel Atkins

Hi Nigel, yes I think it is a UK car, no reason to think any different. It's rhd. I tried to post a photo but it says the file is too large. I'm better with mole grips tbh. It is a 1978 with the 1500 engine, it is de bumpered and looks well cool. I'll probably take a new feed from point 6, sounds like the easiest solution rather than chasing old wires all over the shop.
JE RYDEN

Jon,
just reduce the size of the photo, posts will take adequately large photos (vehicle profile maybe smaller though).

Even the end of model years like 1978 had quite simple (very simple, ancient, by modern standards) electrics so unless previous owners have taken it away from standard then sorting it should be relatively simple and worth pursuing rather than adding non-standard (and unrecorded) deviations.

Often modern "fast" methods of diagnostics with modern tools turn out to be anything but and slow, simple, methodical diagnostics are much better.

By taking a new quick route around the problem now (if it works?) could be ignoring other faults and issues, from possibly the restoration work. The fault could be something simple like a faulty modern (piss-poorly made) part that's be fitted (very common). The brake light circuit on these cars are very simple and effective, if all the parts and elements of the circuit are in reasonable (not even good) condition.

If you buy and read the relevant Driver's Handbook you may even put yourself ahead in some/many ways to possible the person that restored your Midget (not that I can possibly know, I'm only going on this post of a restored car with brake lights that have never worked.

All of us here will want you and your Midget to be in a reasonably happy state of affairs and will want to be able to get you both there if we can - so keep posting, and put up 'smaller' photos, but don't go for your easier solution (yet).
Nigel Atkins

Thanks for your advice with the electrics all. As soon as I've sorted my sons car I'm on it. Jon


JE RYDEN

Image successfully uploaded, thanks. Was just about to get stuck into the MIdget when my youngests Renault started misfiring so we are currently on with that! Yes Yes, coil pack, leads, but compression down in two cylinders, 75 psi. Head gasket aaaaagh.
JE RYDEN

Jon,
that looks very smart.

Altho' I did need a magnify glass. You can upload photos at least twice (plus) that size.

As your car isn't standard you may want to put your 'Vehicle profile' up to be viewed by others (those that want to) to save a little confusion on model details.

Just so happens I'm looking at a 1978 model year wiring diagram, it shows -
. green wire off point 6 of the fusebox,
. bullet connector,
. then on to brake light switch,
. from switch green/purple wire,
. bullet connector,
. to wiring multiplug,
. from wiring multiplug still in green/purple
. to double bullet connector
. green purple wires out to both rear light clusters.

Note if yours is an earlier or later model the original factory wiring may differ from above.

Be very careful following on from previous owners' wiring as you don't want two lives or crossed wires or connections - another 1500 owner may be able to confirm this - and hopefully others on the value of owning the relevant Driver's Handbook - this is NOT the Haynes or even factory Workshop Manual, even though your car isn't 100% standard (not many are now).

Definition is down on this as white borders were included and had to be cropped.



Nigel Atkins

Jon,
one database (which could well be wrong for many reasons) shows your car as being registered in 1979, although even then it might have been manufactured in 1978.

If another is correct and the car has only done 4,000 miles in the last 8 years then you may expect to find other, hopefully small, running wrinkles as issues as you use the car.

The best thing for you and the car, if you actually want to use it (some of us have these as daily use throughout the year including winter) is to regularly drive the car over reasonable length journeys (20m minimum) and to carry out a rolling 36k-mile service check.

For running two things I always consider changing on a classic new to me are the battery and the tyres (regardless of tread depth left on them). That is of course after the safety items of braking (tyres), steering (tyres), suspension (tyres), lights and windows. Engine and carbs (fiddling) are low priority.
Nigel Atkins

This thread was discussed between 10/03/2020 and 19/03/2020

MG Midget and Sprite Technical index

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