Morris Minor Owners Club

I'm having a problem that when I turn the lamps on full and/or press the brake pedal I loose all power, but usually only when the revs are low. The engine dies and all the lights go out but a quick pull on the starter gets everything running again. After a week of not using the car the battery wasn't strong enough to start the car in very cold weather so I charged it. The battery's not old and it charged well. This morning was the third use of the car since then and the first I've had the cut out problem again.

Do I have a charging problem? Should I be looking for a short? This all might have coincided with the interior light not working.

Any help much appreciated.

If it was only cutting out I would say the tickover speed needed increasing to overcome the extra demand on the charging system but lights going out as well needs a bit more thought. You must have a short to earth . Maybe the brake warning lights

The interior light may be a red herring, but it's still electrical, so find out why that doesn't work. Bulb? Fuse? Switch? If it's none of those then it must be a wiring problem which could be leaking a small current to earth.

The fact that the problem occurs with headlamps on full power but not dip and/or when brakes applied, certainly suggests that you need to check the wiring and bulbs on those circuits. The brake lights should be supplied via a fuse, but the headlamps are not fused. If everything else is working OK (horn, wipers, fan) then the problem is most likely to be associated with the circuits that cause it.

Do you have a multimeter that can check charging current and continuity, and a hydrometer or similar battery testing device? When not used, batteries will self discharge, but a Minor should be able to start on the battery after two or three weeks of non-use, even in cold weather.

Must be a short to earth then? It doesn't always happen when I swithch on the headlamps or press the breaks. as always, I find electrical faults the hardest to work out.

Unfortunately I don't have anything to check the charging.

Thanks for advice.

You can get a multi meter from any car accessories shop for about £20 that will do all you need. The fact you can start the car again will tell you the battery is good. Have a good look where the wires go through bulk heads etc.

Maplin will do you a little multimeter for hardly any money - get one ! You can't easily check the charging current - you would need an ammeter for that - but you can easily check the battery voltage. Engine at fast idle should give battery volts of ~ 14, with engine off it should be just over 12 volts. First check - is your fan belt nice and tight ? Second check - are all the electrical connections at the starter solenoid (or pull start switch) all clean and in good order ?

Look for earth problems, those bullet connector earth points can easily get dirty/loose. If the brakes are fused and it was a shorting problem, enough to kill the headlights, then surely it would blow said fuse? Also check the main earth on the battery carrier- mine was only a 1/4" fixing, and came loose easily. A 5/16" drill bit and bigger fixing with a nyloc nut sorted that one out!
How recent is the recent battery? Mine is a budget job, under a year old (no receipt-came with the car) but curled its toes up just before Christmas! Got a Varta on there now for a bit more peace of mind.

Next week - Aldi are selling a battery/alternator tester for very little money.

Your original post suggested that it was a "hard" fault whereby every time you used main beam / pressed brakes, the engine cut out when at low speed. From later posts, it sounds as if it's more intermittent than that, which moves possible causes. Suggestions from others to check earth strap etc are good.

The engine stopping should NOT cause the lights to go out. unless there is no voltage in the battery - the battery should be able to power the lights for at leaat ten minutes without receiving a charge.

Apart from checking that ALL connections are good, I'd now pay particular attention to two areas: The voltage regulator (black box on bulkhead) Make sure all connections are good, and if you don't have the ability to test it, then just swap it for another - make sure that you get the wiring right, move the wires over one at a time. Regulators can usually be borrowed from from fellow branch members, and are easily available from scrap yards, club spares, traders, etc. The other area to check is connections to the coil and distributor. Coil terminals have been known to come loose, and the small black wire inside the distributor, from the terminal on the side to the points. can become trapped under either the cap or the sliding plates, if it's not routed properly. Again, good luck.