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MG Midget and Sprite Technical - 74 MG Midget Ignition Switch

I replaced my 1974 Mg midget
Michael Herrick

I have about half a dozen different wiring diagrams for US spec Spridgets Michael.

Do you have your chassis number handy? And do you have a multimeter to check continuity through the switch in different key positions?
Greybeard

Well theres your problem,

You bought the switch from victoria british aka vicky brit... bad idea

most likly they sent you the wrong switch, very common, the good news is they will take it back or exchange it

My guess is you burnt out the diode pack in your alt, which acts as a sort of one way valve between the alt and the battery, when the engine is running its charging the battry when the engine is off the electicity inside the battey is leaking back out thur rhe alt cuase the diaodes are burnt out.

Or it could be the regulator...which may still be mechanical not electrical im not sure the USA mechanical regulators where updated until the mg 1500 in 1975

Is the alt the factory lucas ? Or has it been uograded

Just a side note... the AC delco single wire universial alt has a huilt in elctronic regulator and takes only minimal amout of housing modifications to install and there only $50 to $75 at the usual 3 suspects (auto zone) it will take some wiring modifications but a few hours with the haynes book it in grasph of most wrench turners


Also ...

the white with red strip is your signal wire to the starter seinoid
The brown (2 differant wires fat and skinny) is the wire that the cars power is feed from and runs thur the alt the white wire is the ignition wire that runs from the dissy thur and back out the rev tachometer

Let me get back home and look up the wiring schematic and see if i can trace down what you hooked up to what.

Sadly vicy brit just sells parts and knows or does nothing else...to which there not that good at

Prop
1 Paper

Btw is your car a 1974 1275 chrome bumper or is it a rubber bumper next generation 1500 with the triumph engine

Thanks

Prop
1 Paper

Im making the assumption its a chrome bumper 1275

Prop
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Sadly my eyes are not what they once were, so ive had to take several stabs at this

As near as i can tell, the ignition switch that vicy brit sent you is for a USA 1978 or a 1978 califonia model

So they completely over shot the correct ignition stater switch by about 4 years FOR your application

I couldnt lock on to a shemantic for the 74 1275, the closet i could get was for the 71/72 with a generator not a altenator

(USA midget mk III AN5) -74886 to AN5 -105500
(Page 203 fig 10.26 haynes manual)



The next one up was for a

(*) AN5 - 105501 to AN5 - on wards to end of 1977
( page 205 fig. 10.28 haynes manual

So im guessing the 1274 and the 1500 may have shared this schematic for sevral years


So i still hold that you ither burnt out the diode pack in the altenator (most likely)

Or you burnt out the manual mechanical regulator / control box... not as likely...how to test it i dont know,someone else can help there

Another possiablity and i dont know. On the generators if you disconnect them you have to re-energize or flash the generator, with the lucas altenator you may have to do the same

But i dont know if the altenator has a control box / regulator thats seprate... i wasnt able to find a control box in the later version of schematic i listed for an altenator

But ... id have the usual suspects (advance auto parts) test the alt for free takes about 10 minutes and you will need a fully charged battry to test it


Like i said, if you have to get a rebuilt alt and a regulator/ control box

Id look into the (single wire) AC DELCO UNIVERAIAL altenator has more power out put for modern steroes and elctronic devices and a built in electronic regulatoer so a litle better then the old stuff

Let us know the details of what happened and what you did

Prop



1 Paper

This thread was discussed between 05/07/2017 and 06/07/2017

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