Ignition warning light comes on when ignition switch off.

[JJ Autosleeper]

New problem tonight. I have an ignition switch that won’t switch off the engine.

When I turn the ignition off with the key the warning light comes on but the engine keeps running. I took the key out but needed to disconnect the coil to get the engine to switch off.

I have a replacement modern Lucas style A127 alternator fitted. It’s about four years old and was very hot after I had tightened up the fan belt when the unit had been squealing under load. Not had this before. I am thinking the alternator is faulty. Anyone know if there is anything else that can cause this running on?

Thanks

 

[Panky]

It sounds like the contacts in the ignition switch supplying the 12v feed have fused together, has the switch been getting hot at all? If the ignition light comes on with the key out it's most likely a bad diode in the alternator but the engine running on make this situation different.

 

[JJ Autosleeper]

No I don’t have a hot ignition switch but I do have a hot alternator. The problem occurred after I ran the battery down trying to start the van after having inadvertently knocked off the coil feed from the fuse box when fixing another problem with a feed to the reversing light switch. The alternator was then hard at work recharging the battery and got very hot under load and the belt started slipping. I tightened the belt up and now I have the ignition light coming on when I switch off the ignition which I have never had before.

Looks to me like an alternator control issue. I can see new regulator available on EBay so I am tempted to try this first:- https://www.ebay.co.uk/itm/22122238...2dsno0CQJ6&var=&widget_ver=artemis&media=COPY

If that does not work then a new alternator?

 

[JJ Autosleeper]

Turns out I had reconnected the power to the alternator from a swithed supply rather than a constant supply. Once I connected the wires at the fuse board the right way it was back to normal.