Loss of lights

[Salad dodger]

Whilst out today my indicators failed, I pulled over to check for problems & found the brake lights & wipers were also not working.
As it happens, a friendly AA man was filling up at the petrol station I pulled into.
Between us we managed to diagnose sod all except yes, they aren't working.
There's only 2 fuses so assumedly it was one of those, both were intact & the bottom one had 12v , whereas the top one only carried 1/2 a volt.
Where is the top fuse fed from? Everything goes into a taped loom, so bar cutting the loom open I'm at a loss

[geoberni]

It really does help to have a Workshop Manual .....
The language used can sometimes mislead too.

...both were intact & the bottom one had 12v , whereas the top one only carried 1/2 a volt.

When you say that do you mean you measured across the fuse, one end top the other, or were you going from the fuse to the Battery Earth or a similar Earth Point?
Because 12v one end to the other is a dead fuse, just as 1/2v, or hopefully much less, is a good one.

There are 2 different Fuse Holders used on the Minor and hopefully you have a Brown wire to the LH side of the top Fuse, with 3 White Wires to the LH side of the Bottom one.
Those are the feed (supply) side.
The RH (output) side of the fuse should be Top (i.e the Brown Feed) several purple wires. The Bottom one (white feed) should be several Green cables.

Your Indicators, Brakes & Wipers are all on those Green feeds. Fuel gauge and heater are also on these green wires.
Can you see where I'm heading, your Bottom Fuse with the 12v should be the dead fuse, not the Top One.

It's easy for a Glass Case fuse to 'look good' when actually the break is hidden by the metal end cap.

[Salad dodger]

It really does help to have a Workshop Manual .....
The language used can sometimes mislead too.

...both were intact & the bottom one had 12v , whereas the top one only carried 1/2 a volt.

When you say that do you mean you measured across the fuse, one end top the other, or were you going from the fuse to the Battery Earth or a similar Earth Point?
Because 12v one end to the other is a dead fuse, just as 1/2v, or hopefully much less, is a good one.

There are 2 different Fuse Holders used on the Minor and hopefully you have a Brown wire to the LH side of the top Fuse, with 3 White Wires to the LH side of the Bottom one.
Those are the feed (supply) side.
The RH (output) side of the fuse should be Top (i.e the Brown Feed) several purple wires. The Bottom one (white feed) should be several Green cables.

Your Indicators, Brakes & Wipers are all on those Green feeds. Fuel gauge and heater are also on these green wires.
Can you see where I'm heading, your Bottom Fuse with the 12v should be the dead fuse, not the Top One.

It's easy for a Glass Case fuse to 'look good' when actually the break is hidden by the metal end cap.

Continuity test across removed fuses showed both to be good.
The bottom fuse had 12v to battery neg from both feed & load terminals whereas the top fuse had only 0.5v at the feed side which obviously carried through the good fuse to the load side too.
I had assumed the supply must not come straight from the battery terminal & must go via something else which was causing the drop in voltage, maybe via a faulty regulator or similar?
I'll have to have a good look tomorrow in daylight as to the colour & number of the wires in the terminals , although most of the loom is hugely faded

[Salad dodger]

It really does help to have a Workshop Manual .....

I do have a workshop manual, but I can't lay my hands on it atm as the missus appears to have 'tidied up'

[jagnut66]

Hi,
I take it you've already tried removing, cleaning up and then replacing the relevant earths?
Best wishes,
Mike.

[panky]

Have you checked the in line fuse up near the control box

[ManyMinors]

It is common on older cars for the fuses themselves to be OK but the fusebox to be dirty and corroded so that electrical faults like this occur.
All the items you mention do indeed have power supplied by the same fuse. A new fusebox is not expensive and can be worth fitting. The in-line fuse supplies only the sidelights.

[geoberni]

Have you checked the in line fuse up near the control box

That's only for the side, number plate and panel lights, introduced in 1966 at the same time as the sealed beam headlights.

[Salad dodger]

Hi,
I take it you've already tried removing, cleaning up and then replacing the relevant earths?
Best wishes,
Mike.

Although not impossible, the chances of multiple earths on all points of the car to fail at the same time I would have thought would be slim

It is common on older cars for the fuses themselves to be OK but the fusebox to be dirty and corroded so that electrical faults like this occur.
All the items you mention do indeed have power supplied by the same fuse. A new fusebox is not expensive and can be worth fitting. The in-line fuse supplies only the sidelights.

The supply isn't there though, there's no 12v unput at the top fuse & the cable was stripped back to reveal 'fresh' cores to test

[geoberni]

You've spoken of the Top and Bottom Fuse, so I;m assuming you have this arrangement, since the later fuse box was mounted with the fuses vertical, side-by-side, not horizontal.
This is not my car, it's one I took from the internet as my car has a modified arrangement, thanks to a past owner.
Ignore the fact that this image hasn't even got a top fuse fitted.....

fusebox.jpg (60.04 KiB) Viewed 2019 times

You've said it's the Top fuse that only has 1/2v at it.
Note, as previously explained,where the colours are.
The Top fuse feeds the Purple circuits, although on this they look Brown-ish Only 2 or 3 output wires, depending on year of car.
The Bottom fuse feeds the Green Circuits.
This is as per the wiring diagram as only the Bottom has the linked output to enable 4 wires to be connected.
The circuits you have a problem with are the Green ones.
What you are describing isn't making sense, unless someone has totally screwed with the wiring in the past.
Please post a photo, a picture speaks a 1,000 words and all that stuff......

NB.
The Brown Wire is the permanent Live, direct from the battery via A terminal on the Voltage Regulator.
One of the White wires comes from the Ign Sw, and the other 2 go off, un-fused, to the Fuel Pump & Coil.

[Salad dodger]

I had another look & the top fuse definitely has no supply voltage, without my workshop manual I'm a bit stuck.
The black feed cable I've outlined is 'dead' & I need to know where the other end would be.

[Salad dodger]

You've said it's the Top fuse that only has 1/2v at it.

This was the reading from the AA man's tester, mine at home shows zero voltage

The Brown Wire is the permanent Live, direct from the battery via A terminal on the Voltage Regulator.
One of the White wires comes from the Ign Sw, and the other 2 go off, un-fused, to the Fuel Pump & Coil.[/i]

So it should be fed from terminal A of the regulator? I'll go check the output on the reg now.

P.s. I didn't see your post prior to posting my last one

[Salad dodger]

The Brown Wire is the permanent Live, direct from the battery via A terminal on the Voltage Regulator.

There isn't even a wire in terminal A
Looks like I'm going to have to do some deeper investigation when it's light again tomorrow, disconnecting things & flagging through for continuity

[jagnut66]

Perhaps it's time for a new wiring loom.......
Not as difficult as it sounds, I replaced the loom on Sally, following the diagram in the workshop manual.
Best wishes,
Mike.

[Salad dodger]

Perhaps it's time for a new wiring loom.......
Not as difficult as it sounds, I replaced the loom on Sally, following the diagram in the workshop manual.
Best wishes,
Mike.

As a last resort this might be the case, but I'd like to find out why it worked one minute & not the next

[geoberni]

As a last resort this might be the case, but I'd like to find out why it worked one minute & not the next

Looking back to your first post, I see your car is only a year younger than mine and mine had a new loom fitted around 1999.

So the answer to your question is because that wiring is around 65 years old and probably had a life expectancy of 10-15 years when it was made.
That 'black' wire as you called it is just the rubber insulation inside the fabric outer that should bear the colouring for identification.
Rubber does not last well; a loom that age is a disaster waiting to happen.

I think this is your wiring diagram, as your car has the original loom.
There could be 2 brown wires connected to A and a single wire on A1, or the opposite way around. It seemed to change between drawings.
But I think this is yours....

Wiring Diagram.JPG (144.45 KiB) Viewed 1962 times

[Salad dodger]

Wiring Diagram.JPG

Cheers , that's what I needed

[ManyMinors]

I must admit that, if it was my car I would be ordering a new wiring loom as already suggested. That wiring is WELL past its best before date and you cannot trace the cables in it because you have no idea what colours they are .
Buy a new wiring loom and a new fusebox and spend a day or two carefully fitting it. It isn't that difficult and you'll have an electrically safe car at the end of it. With the best will in the world, you cannot possibly expect such old wiring to work properly
And. If you really don't fancy doing it yourself, there are plenty of garages, electrical specialists and Morris Minor specialists who'll do it for you.

[svenedin]

I would really worry about the safety of that wiring. The car could easily catch fire.

[Salad dodger]

It is common on older cars for the fuses themselves to be OK but the fusebox to be dirty and corroded so that electrical faults like this occur.
All the items you mention do indeed have power supplied by the same fuse. A new fusebox is not expensive and can be worth fitting. The in-line fuse supplies only the sidelights.

Give this man a coconut
On closer inspection today, the bottom carrier itself was corroded on the contact surfaces.
All the tests I was doing were conducted from earth terminal at the battery to the fuse itself, the pressure from the test leads must have been enough to make contact to the carrier, giving false readings.
A clean up with fine sand paper, a brass brush & some wire wool has brought it back to fully functioning.