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MG Midget and Sprite Technical - Lights failed.

Tried the headlights today, for the 2nd time in a fortnight they failed to light up. This was slightly annoying.
headlamp flasher works, but interior light does not, nor do the instrument lights, headlamps and tails all dead. Horn works too, as do the indicators.
Been trying to work out from the handbook, studying the wiring diagrams.
Tested the fuses, all ok.
The last time it happened, I wiggled the cables running across between the headlights, looked as if they could have been pinched, but that got them working again. This time no wiggling helped!
Any ideas folks?
Dominic Excell

Sounds like the light switch.

The headlamps will work via the flasher as the current comes from elsewhere.

Does not explain the interior light not working.

Eddie Cairns

You don't say what year the car is, but here's a few things to check.

Firstly, does the main beam warning light operate with the light switch in the high beam position? If it does the switch is passing current and it must be a connection problem.

If not, either the dash switch is defective or has no battery current to it.

It's not fuses stopping h/lamps working, as they're not fused, unless someone has modified the cat from OE.

Cars with the 4 fuse box have 2 sidelamp fuses, but it's unlikely both have failed at once.

SR Smith 1

It's a 1970 car SR
No main beam warning light.
I'll check the switch and connection tomorrow.
I think the wiring has been messed about with in the past Eddie, as the instrument light switch is now used for the heater fan, presumably the original attached to the fresh air vent having failed. God knows what else has been changed. The P.O. was a builder, and there were quite a lot of household connector blocks loosely protected with insulation tape in the wiring he did!
Dominic Excell

loosing the panel light switch would help if he bypassed it correctly

SR's good on these things but I'd think of dash light switch but is yours a foot dip switch?
Nigel Atkins

I suspect it could be blown scattered wet toilet paper residue shorting various areas at once

you're paying for your extravagance of not trying to find them

in a way it's blown back in your face, not nice but you price you pay for not using two pegs per sheet

if you want I can put some pegs in the post

they might also help to hold your electrics together or their springs to provide electrical contacts
Nigel Atkins

Ha! thanks Nigel! Luckily my neighbours returned the aforementioned bog-roll. Always need more pegs, so please post them as soon as you can.
Dip switch is on the indicator stalk
Dominic Excell

So a new wiring loom should sort it.

Eddie Cairns

look out for them, one to each pigeon leg

you could check connections on dash switch are clean, secure and protected

or connect passed the dash switch to rule the switch in or out

then if it's the switch disconnected the live to the switch and keep working the switch or take the switch apart and clean and repair as required

this'll test the batteries on your new head torch
Nigel Atkins

Classic case of condenstion namely in the bullets...

Also a 1st sign of grounds going bad

Was the weather cold then warmed up for a day fairly fast

I had condenstion all over my car today
Prop and the Blackhole Midget

certainly been fairly damp Prop - and true, yesterday was a bit warmer - so could be just that. Checks tomorrow will no doubt reveal all (electrically that is! Too damn cold to reveal anything here!)
Dominic Excell

Spent the day in the garage fitting the new clutch cylinder and getting it all going again.
The weather was aawful - driving rain - so the garage was somewhat cold and damp.
Switched lights on to test before starting to pull wires and connections apart, nothing happened. I went ahead and tested the clutch putting it into various gears. I tried the lights again while the engine was running, and they've been fine since! Looks like methodically going to every connector along the line, cleaning, re-soldering bullets if necessary and replacing the connector blocks if needed, and then weatherproofing them somehow.
Nothing seriously wrong by the looks of things anyhow.
Dominic Excell

If your going to resolder things why not fix it properly and put headlight relays in?
Also check for black wire syndrome in the earth returns. If you put relays in use a 25 amp circuit breaker to the relays for safety. You can buy a kit for this from the usual suspects but you can do it yourself for half the cost. Break into the wiring loom as it exits the firewall, see photo, the circuit breaker is to the left of the relays. This is on a 79 1500 so the wiring colours may be different. BTW, the curved tube is the wiper drive. Cheers Rod

R W Bowers

are you sure it wasn't just a case of you blinking slowly when you thought the lights went out?

I'm still waiting for my headlight wiring and switches to burn out from fitting H4 headlights without relays 4 years ago but to be fair my wiring is only about 12 years old however the column switch feels very old if not original and is a little wobbly but still works find as do the lights

mind I didn't get my headlamp conversion by hiding in the blind spot of a reversing truck even if it is cheaper to do it that way ;)
Nigel Atkins

Your light problem could well be surface corrosion of the contacts in the stalk mounted flasher / dip switch. Unless you have relays added like Rod, then all of the current for the headlights goes through the tiny contacts which are only held together with each other by thin metal springs. In damp conditions the contact surfaces build up a layer of corrosion sufficient to stop them working. Either that, or sparking across the contacts erodes them away.

Initially it,s a fault which comes and goes, as it cures itself as the contact surfaces dry out, but eventually they fail permanently, usually on a dark wet night on a mountain road miles from anywhere! (well, 50% of the time in my comprehensive market sample)

The original switches seem to last pretty well,(34 years in my case) but I have had 2 aftermarket replacements both pack up within 2 years. When the second replacement died I added relays so that the little contacts in the steering column stalk now only carry relay switching current.

Guy W

I was told and hope the column switches are better now as I bought a brand new Lucas one about 2 years ago because I thought my old one might wobble apart but as it hasn't fitting the replacement can wait longer
Nigel Atkins

Useful spare to have on a dark wet night then, Nigel. Better put it in the boot!
Guy W

as you know Guy I believe in prevention rather than carrying spares in the boot, if it hadn't already been replaced then first sign of my present column switch playing up and it would be replaced

it's working fine and sits outside in the current driving rain, wet and damp 24/7 (365/6)

I'll fit it with my 'new' steering when I touch-up the paint on the dash but this requires good weather and if it's good weather I don't want to be working on the car but driving it so it needs a day when I can't go out for some reason and they don't really exist

I've also yet to look at the new switch to see if anything needs improving on it but I've no enthusiasm to mess around with car parts so again it can wait
Nigel Atkins

Hi guys,

Whilst all the advice about dodgy pattern column switches is all good, if you read Dominic's original post it says he'd lost all external lights, not just headlamps.

You could disconnect the column stalk and the front and rear sidelamps would still function, so it was never a stalk fault imo.

My money is on a poor connection on the brown wire at the light switch or a duff lighting rocker switch. Probably clicking it on and off a few times has restored the situation.

These rocker switches are fairly simple to prise apart with a small screwdriver to clean out the concealed muck of years and burnish the sliding plate plus the copper contacts.

SR Smith 1

yeap dash light switch was covered earlier, even bypassing it

this is just the usual debate about the need or of relays for the headlights - or thread drift for some
Nigel Atkins

The switches fail because they are carrying too much current through dubious contacts, relays fix this, but of course yoiu must still have decent switches which will last a great deal longer if relays are used. Fixing (duplicating i.e one each side)the earth returns is also mandatory IMHO Cheers Rod
R W Bowers

I don't disagree but the original switches seem to last decades without relays, if electrics is your interest then fitting relays will interest you same as fitting a roll over bar might seem necessary to some but most cars and owners survive without them - it's just a case of different people have different ideas of what's required to improve the cars

my column stalk arm has been wobbly ever since I got the car over six years ago but works perfectly and has never played up at all even after 4 years of using H4 bulbs
Nigel Atkins

I have to say I'm in rare agreement with Nigel. Although electrics interest me, and the effort fitting a relay isn't that great, the original switches didn't need them. Unless of coure you were fitting an array of rally spots, sufficient to illuminate a football stadium. lol

All the toggles on my Sprite are original, and as far as I can tell, so are all the rocker switches, and the column switch on my midget too. Not a relay in sight on either.

Pity we can't buy new originals.
Lawrence Slater

I think I'll go along with the original toggle switches, as the lighting is standard apart from halogens (which I don't think draw any extra current) I just need to clean up and protect all the connections. (Been away otherwise it would have been done already) I also want to play with a new macro lens for my DSLR.... but I guess that must wait....
Dominic Excell

macro - how handy for photos of problems on the car :D
Nigel Atkins

indeed Nigel! It'll take pictures of a gnat's pecker too (as an American friend of mine during college days used to say)
Dominic Excell

Seems I've located the problem - the brown wire that feeds the lighting switch directly from the (new)starter solenoid take-off had a poor connection at the solenoid end. It was one of those bright-plated connector tabs rather than OE copper. I think it may have built up a film of corrosion (we live only 1 1/2 miles from the Irish Sea) and a clean up with fine emery paper, and inside the connector attached to the wire seems to have done the trick.
I must remember that any problem is usually solved by the simplest answer....
Dominic Excell

well done on finding it

I've found modern connectors, like the crimped female spades, can become loose after only a few years of being fitted

how about putting some electric contact grease on the inside of the connections to keep the sea out as well as having fully insulated connectons
Nigel Atkins

That sounds a good plan Nigel - will stop at the local suppliers on the way home from work tomorrow.
Dominic Excell

This thread was discussed between 28/12/2013 and 12/01/2014

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