4 replies to this topic

[enzodog]

My engine will not shut off with the ignition switch on a 1967 Mini Cooper S positive ground.

 

It will operate correctly by removing the small brown/yellow wire from terminal D of the voltage regulator. With this wire removed, everything works normally, including charging the battery from the generator. Disconnecting either of the large brown/yellow or green/brown generator wires, will also allow start/stop with ignition switch but there is no charging of the battery.

 

What concerns me is that the generator warning light remains on when the engine is running, and the generator is charging the battery. In trying to determine why the light stays on, I disconnected the generator so this warning light could not get to ground via the generator field, but it remained on. My reasoning was based on the following article assuming it applies to a generator setup.

The ignition lamp's name has always caused confusion. The lamp has nothing to do with the ignition system, it has to do with the alternator. A better name for that lamp would be "Charge Warning Lamp". The circuit works like this: White wire from the ignition switch to one side of the warning lamp. Brown/yellow wire from the other side of the lamp to the small terminal on the alternator. The small terminal on the alternator is connected internally to the alternator field coils. The field coils are connected on their other end to earth. Thus, when you turn the key to "run", the warning lamp should come "on" as current flows through the lamp, through the alternator field coils, and finally to earth. When the alternator starts making electricity, it brings (internally) the small terminal up to the charging voltage. When that happens, both ends of the warning light wiring are at the same voltage (charge voltage) so the lamp goes "out". So, anytime you see that light "on" with the engine running it means the alternator is not making electricity. With the alternator unplugged there is no way the charge warning light should ever turn on as the light will have no earth connection.

 

I have already tried two other voltage regulator/control boxes.

[mini-mad-mark]

Sounds like incorrect wiring somewhere or possibly the ignition switch has died inside and is not working as intended however you would have ignition on all the time in that case (as that is why the engine isn't shutting off)

 

Maybe try "hotwiring" the car, i.e disconnecting and bypassing the ignition switch with suitable cable and then seeing if removing that cable stops the engine/turns the ignition off which would point to the switch being U/S

[SolarB]

I had a similar problem when I first fired up my rebuilt engine and wiring loom years ago.

If I recall correctly it was something to do with the alternator generating enough voltage once the engine was turned off and slowing down to keep the coil energised. 

It turned out to be a wiring error, sorry, but I can't remember much more of the detail.

[Homersimpson]

It sounds to me like something wrong with the voltage regulator for the dynamo (the plastic box with two or three coils in it.

 

If you look in the haynes manual it should tell you have to check and set this unit up but its probably easier to just buy a new one.

[Homersimpson]

Just to add that if I remember correctly the charging light on a dynamo car works differently as it is just switched on and off by the control box.

 

I've had the same issue previously and despite trying multiple control boxes it was a new on that finally cured the problem, the car was a Jag rather than a mini but the same principals apply.