Morris Minor Owners Club

Have an issue with ignition warning light that does not come on but lamp is OK. Recently replaced battery as dead and discovered that alternator had been run for a week, approx 3 hours operation,without being connected to anything, hence dead battery!
(Don\'t ask why as first car and after servicing, items not fully checked).
Moving on, could this have affected the regulator in alternator?
Could it be an earthing problem with lamp holder?
Everything else works OK.

Cheers

I was always told that you should never run an alternator on an open circuit as it destroys it. Never risked it myself as alternators cost money.
If the light bulb is screwed in tight, the holder is tight in the back of the speedo and the other warning lights work then there should be no problem. I'll check where the other end of the wiring goes when I take the speedo out later. Do you still have a control box?

Yes, it is still their.

Have now checked wiring to lamp, green wire registering 11.9v with engine off and 12.06 running so presume alternator is charging. Lamp still not on. Both green and green and yellow wirs disappear into loom behind speedo so where do they come from or go to. Assuming green is live feed?

12.06 volts isn't telling me is in a charging state. I would expect to see around 14.5 volts. Measure at the battery terminals and see what your meter tells you then... Check that the bukb is teh correct voltage and wattage as it could be coming on but so dim that you cannot see it and also check the wire from the alternator to lamp which is the brown/yellow (used to go dynamo to control box and should now just be joined).

What year is your car?
Stupid questions first
Are you sure you have the correct bulbs in the correct holes?
The ignition warning light should have a white wire going to the ignition switch term 2 and a brown / yellow wire originally going to the control box term D but on a rewired car it goes to the alternator.

Provided the alternator has been wired up correctly - and not through the 'control box'! Take the little wire off the alternator (engine not running) - and touch it to ground - the red ignition light should come on - assuming ignition switched ON of course! Does it ?
And sadly yes - running the alternator without battery connection will very possibly have damaged it. But how did the car start and run like that - was the large wire off the alternator ?

In no particular order answers are;-
1. 1970 H reg 4 door.
2. Alternator was working and light did come on.
3. Remembered that it was 2.2W on shroud of lamp, can't remember but think 12V.
4. Bulb screwed down as far as possible, but don't know how to check if fully home.
5. Brown/yellow is conneted to alternator not via term D on control box.
6. Haven't checked back of ignition switch as only groping around back and didn't feel any loose wires. How does the white cable connect with the green and green/yellow cables supplying lamp holder that appear from loom?
Think this could be the answer as was replacing heater with a mini one over the week-end so may have dislodged a cable.
Is access to the ignition switch easier by removing speedo rather than glove boxes? If so how easy is it to remove speedo. Cheers

Final answers:-
7. Started via handle and merrily chuffed on but no little red light, amazed 18 year old son these things exisited and worked.
8. The multi-connector with all 3 cables had been removed for the week!
Cheers

Hi redduster - you still need to tell us if the light comes on when you earth the alternator connector with ign on and also the battery voltage when engine is running

If the car was run with alternator disconnected, the alternator will definitely be goosed. Off load an alternator produces over 400 Volts into the regulator inside the alternator. Diodes will be fried.

The white wire should run straight from the ignition light to the ignition switch
The brown and yellow wire disappears into the loom and appears at the control box or alternator.
It is easier to remove the speedo to get at the ignition switch, but you may need to take the glove boxes out to get at the speedo screws especially if you haven't taken a speedo out before.
You may have to take the steering wheel off to get the driver's glove box out!!!
If you've got green or green / yellow wires you've got the wrong bulb holder

So it proves my drawing office mantra of " If in doubt ask" works.
Success. Ign light works and the prize for the correct diagnosis goes to Mike P,thank you sir!
Ofcourse if I had been looking at the correct indicator lamp , which had a broken lamp, which once replaced shone, would have solved the problem! It has answered a number of questions or rather as Murphy,sons name for car, has not been used in anger yet, we wait and see.
Alternator is working, not goosed.
I assume spare lamp and green / yellow wiring for oil sensor that isn't fitted!
So thank you one and all.
No doubt with challenges son has , electronic ignition, thermostatic fan, discs - as Arnie says - I'LL BE BACK.

You should have a terminal on top of the oil filter housing for the filter warning light connection unless it has been changed to a canister filter but its not worth worrying about. I use my warning light for the trailer indicators