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MG Midget and Sprite Technical - I HATE electrics!

All I did was take the tacho out to inspect it. Now the headlights don't work and the horn which is usually so sensitive that it goes off if I look at it in a funny way, doesn't work either! They don't even appear to be in the same circuit. Arghhh!

Everything else works. The sidelights are ok, the panel lights all light up, the ignition light comes on, car starts, wipers are ok, the heater fan runs and the indicators work. Not checked the brake lights. Fuses are intact. No dipped heads or main beam. No horn.

The main beam light was on regardless of the position of the dip switch until I stomped on it a few times then it goes on and off with the dipswitch but no headlights.

Got to be something simple but I can't see any disconnected wires.

I hate electrics!
Stuart K

Is it raining outside???? or lots of humidity?

yeah, ask me how I know to ask that question.

another possiblity is something got jared when taking the tach out, check the wiring under the dash...

you are correct, what ever it is, its going to be stupid...simple as a small amount of corriosion in a bullet connection, to a wire connection falling off the headlight switch. your just going to have to take the time and patiance and track it down

prop...2 flash lights duck taped to the bumper can get you home at night...Prop
Prop

It's not my favorite either. That's why it's called electrickery...

Glen
G. D. Phillips

actually the offical nick name is "Prince of darkness"

Prop
Prop

prop to be complete

Lucas : "Prince of darkness"

Onno Könemann

Did you remove the cowl from your steering wheel?
And how did you get passed your indicator switch?
There is a wire there for the headlights wich has a tendency to come loose and then the current flowing heats it up when the contact is bad and then it stops working. The horn wire is in the same region, maybe you pulled the plug on that one.
Alex G Matla

I didn't touch the steering wheel cowl. Just unscrewed the nuts securing the tacho, withdrew it from the dashboard, disconnected the wires to it and took it out. Reverse to put back in. The only grounding cable disturbed was one which was attached to the tacho dashboard securing bolt which I actually cleaned up before reattaching.

I spent all last night checking around the wires under the dash but can't find anything out of place or disconnected. It is driving me nuts. This weekend I'll have to take the whole lot apart if I don't find an obvious cause.

Could a dipper switch malfunction (on the floor on my model)be causing it? The high beam light was continuously on when the headlight switch is activated although no headlights were working.

I am fortunate in that the wires are actually coloured as they are labelled in the manual so tracing them is not quite as difficult as some cars where the spaghetti has all been replaced with any old cabling and impossible to figure out.

By the way, is it normal for the coil to get hot if the ignition is on? Noticed the coil got warm/hot whilst I was fiddling around. Didn't have the engine running just left the ignition on for short bursts whilst trying to trace the wiring.

Stuart K

Coil overheats after a hour or so with ignition on and points closed; it's not rated for continuous current. If you need the ign on for problem tracing etc., then you should disconnect one of the coil terminals.

You need to chase the volts around the headlight circuit with the switch 'on' until you no longer see +12v.

It's well known that car electrics don't respect Kirchoff's laws. I don't blame Lucas... our cars weren't specified/designed for 20+ years of operation, like today's cars. Most of them rusted out in less than 10 years in any case...

A
Anthony Cutler

I am with Anthony on this one, the prince of darkness is total garbage. Lucas electrics on our cars are great and far better than todays efforts.

My MGA for example has no modern relays yet with its original 50 year old switches and wiring loom has no problems whatsoever with electrics which is also the case with my midget.

Stuart which year car do you have?
Robert (Bob) Midget Turbo

Robert has No problem with lucas wiring.

I have to agree, when one sells there soul to saten, life on earth is pretty good for the damned....LOL

Staurt...I have to agree with your thinking, I cant back it up with chapter or fact, but certianly logical choice to start from...Id go ahead and replace the dip switch on the floor, its already bad, so its not like your loosing anything, besides how much can they really cost...being that it controls the high and low beems, its got to connect to the headlights some how....mmmm, look at the grounding on the dip switch 1st for corrosion, and take it pyhsically off the car, just to avoid the ol "its looks fine"....six weeks later and $800, let me take that off and take a loo...WTF is that hidden mess!!!!

Prop
Prop

stuart has a mk II midget iirc
Onno Könemann

Yes MkII 1965, 1098cc. The wiring seems to match the plan in Haynes apart from the ignition light and the high beam light which are illustrated in the speedo and tacho respectively but are actually the other way around in my car.

Looks like I'm spending the weekend trying to trace the broken connection. I'll start with the dipswitch then the steering column because if the horn has gone there may be a grounding problem there.

EDIT

Just discovered on looking through the catalogues that my wiring is slightly non standard. Didn't realise there was a separate panel light switch. My panel lights come on when the side lights are turned on. The original panel light switch is wired to the motor of the heater unit - the original heater switch is in place but broken. Which means I've been tracing the wrong wires on the diagram. Ho hum.

Stuart K

I found it easer to break down the schmatic by drawing out just the circuits you are working on.
A PO may have jury rigged the wiring.
When I restored my 75 I used good contact cleaner on all connections and on some I used files.
Also helps if you have 45 year experence in elctronics.
RC Bishop

Well I fixed it in the end. Took a lot of finding as I had assumed the problem was under the dash where I had been fiddling. Wrong. The ground cable from the lights attached to the front inner wing was dodgy. Total coincidence that it had failed after I'd been messing around under the dash. Like I said, I hate electrics.
Stuart K

Sorry to say and no use for you anymore but for the archives: 99% of electric problems are... earth problems.

Bas
Bas Timmermans

Bas,
I agree with you. Most of these electrical problems are ground/earth problems. Just spent a week getting lights, wipers, etc. working on my '78 Midget. Learned the hard way on previous Lucas system in a '71 TR GT6, but that's another story in a previous life!
DL Rhine

This thread was discussed between 02/07/2009 and 06/07/2009

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