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MG Midget and Sprite Technical - Electrical

I have done a lot of work on my 75 midget and want to get it running for the sprong weather. All was well and the can was running well. I had to replace my battery and rewired my horn, replaced the wiper motor and now I have no power. The battery is 100 percent, I can had start the car by jumping the solenoid. The wipers do not work, the pump does, the head lights and marker lights come on, brake lights work. The turn indicators don't. The big thing is that when I turn the key I can hear the regulator clicking and that is about as much action as I get. The fuses are all 100 percent. Does anyone have any suggestions? Do you think I should change the regulator or maybe it is referred to as a control box.Is there a way to bypass the regulator? Is the regulator even that important. I'm baffled by this problem.
T Leach

Hiya,


Firstly what year is this car?

Assuming it's a 1500, which was launched late '74 it shouldn't have a control box/voltage regulator anyway? All anternator equipped cars had internally regulated alternators.


You mention, "the pump runs", if this is the petrol pump it's non oe or we're talking 1275.


Have you checked the current is passing thro the ignition fuse, ie the white/green circuit? Tho u say the brake lights work and they're feed by that circuit.



More info please.


Regards Steve
SR Smith 1

"All was well and the can was running well."

"I can had start the car by jumping the solenoid."

So contrary to what you say, you DO have power, but not from the ignition starting position.

Being a '75, it must be a 1500?

There are a number of things to check, but first, more clarity please.

Don't change or buy anything until you know what the problem is. Since all you did was make a couple of changes, there can't be a lot wrong, since it was running before those changes.
Lawrence Slater

Steve, first sentence... its a 1975, must be 1500.

you mention symptoms started when you replaced the wiper motor. what if you disconnect the wiper motor, do things like indicators then work and the car start? I think the switches and connectors at the wiper motor can be a source of bad connections and green circuit shorting to earth.

cheers
Malcolm
M Le Chevalier

Malcolm - Steve's point was that a 1500 has an Alternator (so no regulator) and a mechanical fuel pump not electric, though I suspect "pump" actually refers to the electric washer pump on a 1500.

Dean Smith ('73 RWA)

Sorry, crossed wires I think (ha ha!)?! Steve was asking "what year is it?" when Mr T said it was a '75 in his first sentence.

The washers on mine are not electric, did US/Canadian spec cars have an electric washer pump?

Malc.



M Le Chevalier

IIRC late UK cars did have electric. North America may have had them earlier, as they did with everything else!
Dave O'Neill 2

My assumption is the pump is for the window washer fluid...and yes they where electric as far back as mine in the usa ... 1971

So whats NOT ....

1.turn indicators
2. Washer pump
3. Starter solenoid

Id check the battry connection 1st, clean and tight, next id check your earth strap is good and in place... im not sur where its actually located

The next area that may account for indicators and washer pump is the stock its self that connects to the steering colomn as the indicators and washer pump both share the same unit...could be just a bad ground in this area as well

Prop
Prop and the Blackhole Midget

Are the battry post and Batt. cable connections free of any contact... there not accidentally making contact with the firewall/bulkhead wall... that area is very close with the battry designed for our cars, I use a 1 inch thick block of wood to ensure there is no contact between battery and fire wall

Prop
Prop and the Blackhole Midget

Suspect bad earth on starter solenoid. That's the usual symptom of click, click when you try to start. It should be earthed well to the body. If you have repainted the engine bay there may be other earthing faults to come.

Rob
Rob aka MG Moneypit

Good shout on a poor earth to the solenoid body, lots get baffled by that.


The wiper can't stop the car starting, the ignition is on the unfused white circuit. If it had a problem the fuse would be blowing and would cut the power to other to other circuits.



Unlikely to be the column stalk Prop for these symptons, although on the column stalk, two totally seperate circuits and the indicators dont switch earths in the column stalk.



We need more info to assist this guy.
SR Smith 1

Thanks SR

It was just a guess based on the turns signal and washer switch is shared on the same device

I agree, its got to be a grounding issue

I wonder if we talking 2 differant issues...it could be gool ol Mr condenstation playing up now that the weather is warm(er) during the day yet still cold at night.

Im currently still trying to figure out my turn signals and fuel gauge... there both playing up at the same time... but very random non repeatable system... sometimes they work and dont work, seems to depend on war issues in the middle east then on anything electrical/mechanical on the car

Prop

Prop and the Blackhole Midget

Thank you all for the interest and comments. I will clarify. It is a 75 midget 1500. I was in fact referring to the windshield fluid pump. The headlights work, marker lights work, break lights work. The heater fan does not work. When I turn the ingnition key a clicking sounds comes from that "thing" screwed to the firewall. It looks like a bread toaster with wires coming from the bottom. I can get the starter to operate and turn the motor using a breaker bar across the contact points at the solenoid. I will check the battery is clear of the firewall tonight and disconnect the new wiper motor. I am baffled. I will try and jump the components at the connections under the dash tonight as well. I am beginning to think I screwed up the earth/ground somewhere too. By the way what is that thing on the firewall. I thought it was a regulator/control box.
T Leach

I have an update. The wiper switch is broken and I am going to have to try and fix it again or replace it. The car will only turn over from the ignition switch with the headlights on and the turn indicators only work with the hazard switch on. I think this is a grounding/earth problem.Or some kind of short under the dash. Any advice you can offer will be gratefully appreciated.
T Leach

Hi TL and all, this link may not help with the problem but at least we may all get a laugh out of it
http://www.mez.co.uk/lucas.html
Cheers
Rod
R W Bowers

"The car will only turn over from the ignition switch with the headlights on and the turn indicators only work with the hazard switch on."

Have you moved any of the wires on the ignition switch?
Lawrence Slater

That thing that looks like a toaster with wires coming out of it........Could that be his instrument voltage stabiliser? It derives it's power from a pole on the Ign Sw which cuts off the power to to it when you key the starter, which is why all the insts drop to zero until you let go of the key. So it would make/break when cranking. You wouldn't normally hear it over the engine cranking.

Turn indicators only work with hazards on.........The hazards use a separate switch and flasher unit, so possibly a bit of a red herring.

I think Lawrence is on the right track - for some of the faults anyway.

If it starts from the key with the lights on there's not a problem with solenoid chassis earth.

Here's something you can try TL. Disconnect the wire from the solenoid primary (coming from the switch). If it's original it should be White/Red. This is for your safety as it will prevent the engine turning over.

Connect a voltmeter between the terminal on the end of the wire and the battery neg pole. If you don't have a DVM one of those light-up circuit testers will do, but check it lights up first across the battery - they are notorious for failing at the wrong moment!
Get an assistant to key the starter with the lights off. If you see no voltage, try again with the lights on. If you see voltage you have confirmed it's a wiring issue. Probably at the switchgear end in the car, as Lawrence says.
RS Hughes

The dwg shows the heater fan and wiper motor share a power supply. It comes from a pole on the ignition switchset, but there is an in-line fuse which may not be obvious among the snakes wedding using wedding cars sevenoaks of wires behind the dash.
This fuse must be ok as it also supplies the screenwash pump, which is working.

Hmm...

As the fan and wiper motor are both non-op you could have an earthing prob there, as Prop suggests They are both earthed via Black wires to the chassis - do they share an earthing point, by any chance?

The turn signals could be a dud flasher unit. The unit with Light Green/Brown and Green wires is for the signals. The one with Light Green/Brown and Brown wires is for the hazards.
Or it could simply be a wire dislodged. The power supply is ok if the hazards work as they're supplied from the same fuse.
RS Hughes

Im thinking the turn signal flasher is gone to heaven also... there cheap and in most parts stores...on the 1500 I cant say 100% but on myv1275 its on your drivers side inside the engine bay on the firewall close to the bonnet hinge...it will be cylinder shaped with 2 wires coming out

The starter only turns when the head lights are on...thats crazy, ive not heard that before

Id say pull the battery cables off the battry and have a look inside the cable twin windage at the claps and look for hidden greenish white powder build up...if there is cut them back to clean wire

Changing to a new battry may have upset, the corrosion a bit

Btw... why did you replace the battery, and how old was it.... what kind of condition are your battry cables in...on a scale ofn1-5

Does your choke cable get hot after turning the starter?

From your discription... it does sound like you have a mechanical control/regulator box... can you photo it for us

Prop

Prop and the Blackhole Midget

Hi again,


Your description of the "thing" screwed to the bulkhead is confusing me. Could it be some sort of old alarm or immobiliser device? A pic would be good. It may be cutting the supply to the starter solenoid.


Does the wiring coming from it look part of the original loom or it is taped to the outside of the harness?


Only cranking when the headlights are on is a very odd fault indeed.





SR Smith 1

If the indicators only work with the hazzard switch on, that implies the switch has gone wrong. The off position on the switch allows normal operation of the turn signals and they often go bad from lack of use.

Heater switch is also a common failure point due to how the switch works. You've already found the wiper switch to be broken so that probably explains that.

Seems like a lot of unrelated issues. Confusing terminology is not helping.

As has been mentioned, making sure the solenoid has a good ground is key to good starting. Remove the mounting screws and bare metal the area, as well as the base of the solenoid, with whatever sandpaper etc you like to use, then see if it works. If not it may simply be a dead solenoid. They do fail time to time.

Double check the ignition switch wiring. If the white/red tracer wire doesn't get power in the crank position then you have wired it incorrectly or the switch is faulty.

That thing on the bulkhead (firewall) is anyones guess. It sounds aftermarket to me, but could be something simple like a relay!
Roadwarrior

Roadwarrior, agreed on the possible broken hazard switch not allowing power to the turn signal flasher unit. That is another possible.

Also agree there seem to be several unrelated issues.

Re: the starter solenoid - since it works when the lights are on it implies that the solenoid and earthing are ok. Wouldn't work at all otherwise. Always good to check the earth is good anyway, though.

Still leaning towards crossed wires somewhere on that one.

On the wipers/fan issue I'd suspect earthing as mentioned. They come from different switches so not so likely that both switches are duff. Also the wiper switch should be a combination wipers/screenwash switch, same as mine, and the screenwash works, so that switch is probably (tho' not certainly) okay.

Would be good to have a happy-snap of the mystery device on the bulkhead.
RS Hughes

D'Oh........just noticed TL said the wiper switch is broke. Bum.
RS Hughes

Rod, taht was a good link. Had a great laugh and now I am re-energized. Had I know the value of all that smoke I would have captured it. I am sure my wife would like that ratherthan it billowing into the house.
T Leach

This thread was discussed between 01/04/2015 and 03/04/2015

MG Midget and Sprite Technical index

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