Morris Minor Owners Club

So here's the thing -

The engine and gearbox have been out of the car for some painting etc. They're now back in no problems and tonight was meant to be the first 'test start'.

The car has an alternator conversion (fitted by previous owner) and the powerspark style upgrade to the distributor.

The engine turns over no problem and the other electrical items work - however, no spark. Using a meter, we determined there IS power to the alternator, but can't see where the coil or dizzy are being fed a live (basically, there are no spare leads and everything I took 'off' has gone back 'on' - so far as I can tell, in the place I took it off from (used labels)

After a while we noticed that with the ignition 'off' the oil light, fuel pump and other ancillaries on that circuit were remaining 'on' - even when we checked the ignition switch and unplugged everything from it. So there's a short circuit, which if we unplug a lead from the alternator, no longer shorts and the lights go off etc.

Can anyone advise?

1. With an electronic starter conversion, should the coil be receiving a live from anywhere? If so, where!? (There is one connection on the loom not in anywhere, but it isn't receiving any power so think it's old wiring and in any case it can't reach over to the positive side of the coil so not convinced by that...)

2. What would cause the alternator to short the circuit its on? Is it definitely the alternator or should I check elsewhere?

3. If it is the alternator, presumably it's toast?

Please ask me for more detail if you need it... until today things were ahead of schedule to have it as my wedding car - I now have 8 weeks to sort this new electrical gremlin with your help until the big day!

Location?
If you're nearby I could help..

John ;-)

photo of that side of engine will result in an answer to the problem,the lead you pull from alternator may be the one that should be fitted to the side of the dizzy,it's easy to get them wrong unless you have experience with it.

John, I'm just off J3 of the A50, near Derby, if that helps?

Will take some photos later - I thought I'd labelled everything up, but obviously missed something!

The colours going in to the alternator Are brown, yellow and yellow (top to bottom) - then the single wire on the bottom that's on its own is black, and that's the one that killed the short circuit when I pulled it out - though any of them may have done that.

The connection that at present is loose and not registering any current is white - which in the old wiring colours would be live! It wouldn't stretch over to the + side of the coil, but would reach to the - .

There isn't a live going into the coil or dissy, and having slept on it there HAS to be a live going into it somewhere, otherwise how will it get any power? Which suggests to me I have a wire in the wrong place!

Southside of Derby,just a tad too far , will wait for the piccies..

John ;-)

I also have an alternator and electronic dizzy and negative ground. My wires are thus: white wire from loom to positive side of coil (this is powered only when key is on). Red wire from dizzy to positive coil, black wire from dizzy to negative side of coil. My alternator has a large brown wire to solenoid, thin brown with yellow stripe (this goes to the ignition light) and a thin brown with blue stripe which goes to solenoid. Hope that helps.

in the original wiring the white is from the ign switch to coil ,is there a switched live from the white or from the black which is on the alternator.the coil should have a switched live to the terminal +,and a wire from sw to distributor.Its possible that different wiring has been fitted you need to find the switched live before going any further.

Photos attached!

I have at the alternator - thick brown/yellow at the top, red in the middle, thin brown at bottom.
In the bottom photo, the longer (black) wire was going to the bottom slot on the alternator, and the white, short one was loose. I'm guessing the white needs to go to the positive side of the coil?

Extra detail - with ign 'on' and alternator disconnected, all three alternator wires are pulling 12.5 volts, as is the longer of the two wires in the bottom picture with black flex. The white however continues to show nothing.

Should I be swapping the white and black? And send the live black wire to the coil and put the dead, white one into the bottom socket of the alternator? (I may have mis labelled)

I'm sure this has been keeping you all up at night like it has me..!!

In any case, I applied some logic and sorted it - think it was a case of mislabelling on my part.

Since the coil had to get a live from somewhere - and the live that was down there seemed surplus to what the alternator needed since the other 3 were all live - I popped that onto the coil and put the 'dead' one into the bottom of the alternator (assuming earth of some description)

Started first time like we hadn't been messing around for hours the night before. 14.5v across the battery so alternator working ok.

So essentially - a 2 minute swap of two wires has solved the issue I spent a few hours scratching my head and looking at circuit diagrams for... who'd have a classic car!?

the alt is earthed via the case and engine I would disconnect the white and start up and check the battery with meter that you have 13 to 14 volts showing alt is working .Well done with fix,it's easy to mix them up.

Will try that - thanks!

Possibly it's the other end of the wire disconnected from the control box that used to go to the Dynamo...

T