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MG Midget and Sprite Technical - Help, Electrics!

Hi All,

Another day, another (new) problem with the midge!

It all started a few weeks ago, when I started her up, and suddenly everything died! No electric power whatsoever. So I had a fumble around and eventually figured out that what seems to be to blame is two (or perhaps just one) of the wires on the right most side of the voltage regulator.

(It's one of this type I think - 1972 1275 midge http://www.ebay.co.uk/itm/New-Voltage-Regulator-MGB-1963-1967-MG-midget-62-70-/150644526747?pt=Motors_Car_Truck_Parts_Accessories&hash=item23131d0e9b#ht_500wt_922)

When I wiggle the wire a bit, it makes a connection and everything came back to life. The problem went away for a few weeks and I assumed (stupidly) that I had cured the problem. Now during the last couple of days, it seems to die regularly. The ignition light seems to be on or slightly flashing faintly most of the time.

So today I dived under the bonet to have a look. It would appear that the right most connector (if you are looking at it from in front of the car) is getting very hot. So hot, infact, that it has melted the plastic casing that it comes in. I did a little test myself, with the radiator fan on, i pressed the contact back a little. I heard the fan instantly start running much faster, however, I saw the bit of metal in the contact getting red hot!!! So I quickly scrapped that test!

Does anyone have any ideas how to solve the problem? I'm thinking a new voltage regulator, but not 100% sure to be honest and wanted to ask you all.

Incidentally, the fuel gauge just started playing up yesterday. It can't decide if its full, half full, or just empty, and won't tell me anything else!!

Many thanks, if anyone could help it'd be grand,

James
J Walker

>>It would appear that the right most connector (if you are looking at it from in front of the car) is getting very hot<<

what colour is this wire?

I think you've learnt a bit from your mistakes (we all get wishfull thinking sometimes too)

did you disconnect the battery, just to be on the safe side

might also be a good chance not only to sort out this problem but also to deal with battery, battery posts, lead clamps and battery and engine earths

but lets start with wire colour and possibly disconnecting the battery (neg first)
Nigel At

Hi Nigel,

It looks like a brown wire from what I can tell. (although I think they are all brown!) There is a bank of, I believe 4 or 5 together, and then the two together that seem to be the troublemakers!

Thanks,

James
J Walker

James letter on box terminal then

or a photo

but still a good time to take the battery off, check the elctrolyte levels in the battery and top up with distilled water if required and put the battery on charge, overnight

if I'm reading the diagram right with my poor eyes and magnifying glass they got to starter solonoid and lighting switch

fuel gauge might return when everything is sorted (perhaps)

Nigel At

James,
My guess is it's a brown wire? (not really a guess as I've had many of these apart!)
Wiring diagram has this as the main feed from the battery (probably via the starter solenoid).
Clean the terminal and replace the connector as it has overheated due to the joint presenting a high resistance.

While you are at it you might as well clean all of them.

Post how you get on and come back with a new thread if the fuel gauge is playing up after you fix this problem. Some faults are connected and it's better to deal with one at a time. The trick is knowing which one comes first!

MGmike


M McAndrew

Hi Nigel,

Just had a look, in the poor light I think that the letter on the terminal is B

Thanks,

James
J Walker

yes sorry I meant to put B

James did I misunderstand you or is it that the connector (male) tab/spade on the control box has melted

if it's the female spade connector on the wire as Mike has spotted then check the other wires and connectors to and from it

all best done with battery disconnected

I was concerned as the other end id the black earth wire

my modern '73 car doesn't have the contol box :)
Nigel At

as Mike's put checking the rest are clean, secure and protected is a good idea

I reckon doing this with the battery, leads, earths and main starting wires helps no end with starting the car and not straing the battery

all electrical connections, wires and switches are worth checking in stages or as you go along with other jobs to see they're clean secure and protected as the electricery will get through better giving more power to what ever and this will help to prevent some future problems

things like the horns soon let you know if there a slight blockage in the path

and think of those bullet connect just behind the rad grille, poor things out in all wethers

even cleaning the fuses and holders can make a difference

yours bright lights Atkins
Nigel At

Well, I managed to have a look this morning and found a couple of things!

Firstly, all the connections were getting a bit dirty, so I've cleaned them all up and seem to be much better. The connection on the B terminal was infact making a very loose connection. So I've cleaned it up as best as I can for now and crimped it on much tighter. Gave it a quick check after a shortish drive and the connection didn't feel hot at-all - Result!

Also it would appear that the earth connection wasn't even connected properly at-all! It seems that when it was last taken off (not by me, I might add!) it wasn't put back on properly, and the connection had recessed back a bit in the plastic holder, so cleaned that one and put it on too!

Fuel gauge still seems to be playing up however, not sure where to start with that one! But at least the ignition light isn't coming on and off all the time again!

All the best,

James
J Walker

James,
the control box and it's connections have been touched previously and the connections have got or were left loose and dirty

this probably applies to others wires and connections on the car so a check on these in stages or as you do other jobs will probably give rewarding results

a battery and connections and earth leads in good condition will repay you greatly with sorting electrical problems

as Mike has put another post would be best for your fuel gauge

but as I post about fuel gauge and its bulb not working on another board I've copied and pasted below for you, see if any of that solves it:

post 1) Fuel gauge and it’s light not working - probably the earth connection – an earth wire connects to the case of the gauge on the threaded rod that comes centrally off the back of the gauge body, this also locates the bracket that holds the gauge to the dash – this probably just needs tightening up (in other case, possibly not yours James)

The bracket needs to spread slightly to locate either side of the gauge on to the dash

Have a look and report back (forget this bit)

Wiring diagram in owners Handbook

post 2) All connections on the car must be clean, secure and protected or problems will arise

The fuel gauge has two wires connected on to it – one green/black the other light green/green – check these are connected tightly

The fuel gauge also has a voltage stabilizer that sits behind the dash elsewhere, the connections to this could be poor or broken or the voltage stabiliser not working

The light green/green wire from the fuel gauge goes to the ‘bi-metallic instrument voltage stabilizer’ via the wire loom

From the voltage stabilizer goes a green wire to a connector then on to the fuse box

The green/black wire arrives at the fuel gauge from the fuel sender via a connector under the car close to the tank this could well be the culprit or the wires to it (in other case and possibly yours James)

The connectors and bullets can get furred up and need cleaning up – don’t replace unless you have to as new bullets and connectors are rubbish I’ve found

The wires close to bullet connectors tend to get the insulation cracked off and/or frayed wires which means renewing connectors or insulation with something

Fuses should be glass with paper inside showing 17 amp continuous 35 amp peak the modern 35 amp fuses look very similar and are often fitted – two spare fuses should sit in the fusebox

- if it is the voltage stabilizer you can get modern replacements for that, let me know I'll give you the links

lastly I got the informatiom about your wiring from a diagram in the fabulous owners Handbook, it contains loads more information, for £7/8 it's the best investment you'll ever made to your car - (Ref: 0057) - http://www.mgocshop.co.uk/catalog/Online_Catalogue_Handbooks_5.html
Nigel At

Thanks Nigel,

I'll have a look at that when I get back from work tonight and let you know what I find!

Cheers,

James
J Walker

I'm actually out early evening driving the Midget on a local Sporting Bears meet

last time I done that is when I discovered the suppliers had sent me the wrong fan for the electric cooling fan luckily my cooling system has been dealt with many times (more than I wanted to) so all the dashing about showed it was getting warm but not overheated - plus the typical English summer cool wet evening helped

I'll be back later eager to hear how far you've got and remind you of all the bits you've missed :)

happy hunting
Nigel At

Unfortunately other non-MG related problems prevented me doing much to her last night. Managed to clean up some more contacts and earths however and am happy to report that things do appear to be working much better! Starting has improved by far the most - she's starting on first turn of the engine now instead of a long slow turnover before coming to life!

I think I'll have to postpone my fuel gauge inspection until this weekend - We'll see how it goes!
J Walker

I got my rad grille restyled by an unfortunate pigeon last night so I'll have to take it off to straigthen it

whilst I'm doing that I can have another go at getting both horns working together properly - oh what great luck it just been covered in wayoil at the front by B&G with their last work so I'll spend more time cleaning it and myself than actually repairing anything

as I put before battery off recharging (checking water levels) and cleaning battery posts, clamps, leads will also help no end

I'm not a fan of braided earth leads or particularly the engine strap but if they are clean not frayed and secure then they might as well stay, I prefer the insulated multicore type of leads

good luck I'm sure the more you do the more improvements you'll find - don't forget to check the fuses are the correct type and clean fuse holders (battery out!)

cheers
Nigel At

This thread was discussed between 10/08/2011 and 12/08/2011

MG Midget and Sprite Technical index

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