Engine not switching off?

[kit of bits]

Hello chaps
I have my 1972 pick up running and electric’s working.
The engine starts and runs nicely but when I turn the key to switch the engine off it just keeps running?
(Centre ignition switch model)
Any ideas..Dave..

[Peter Laidler]

For how long does it keep running? Or is it just running on lumpily~?

If it doesn't turn off at the key then it seems to me as though the key is not switching off the power to the ignition circuit. You turn the key OFF but the electricity from the white wire is still powering up the brown/blue ignition circuit.

Answer,Remove ignition switch and start car. Turn key to OFF and disconnect the white ignition wire. If engine stops, switch is faulty.

I could be wrong but that's how I see it.

[kit of bits]

I think it’s a faulty new switch, that can go in the bin with the new faulty solenoid!
D

[Oneball]

Are you sure the switch is wired correctly and you not got the ign on the always live terminal?

[kit of bits]

I’ve double checked and then swapped them around just incase something was wrong..
D

[Polarsilver]

Dave,
Did you remember to fit the engine Earth strap.. otherwise try a Test Light to look see what is staying ON when it should be OFF.
There is a new Ign; Switch here that you can try if that helps.

[kit of bits]

Thanks for the offer Norman I’ve already ordered one, I’m sure it’s something simple..
Yes all new wiring and earths..
D

[Rubber Sprung]

Has it got an alternator ?

[timmy201]

Is the ignition coil getting 12v when the key is off?

[kit of bits]

Has it got an alternator ?

Bob yes alternator..

[kit of bits]

Is the ignition coil getting 12v when the key is off?

White wire on coil is not live when the ignition key is in the off positions..

[Rubber Sprung]

I once had a new loom with the little diode missing on the small wire from the alternator which I think feeds the warning lamp or excites the coils in it, was sending a back feed and gave the same problem .

[kit of bits]

If I unplug the alternator all works as it should
D

[Oneball]

Disconnect either the ignition warning light or the feed to it from the alternator and see if it’ll stop. If it does then that’s feeding your ignition coil as Rubber suggested. I don’t recall Minis have a diode in the loom but then the ones I play with started life with dynamos. What ignition system are you using?

[kit of bits]

Right
alternator is plugged back in & warning light bulb removed, works perfectly switches off with the key!
What next I get why it’s now switching off but what’s the fix..
Dave..

[Oneball]

Rubber Sprung’s suggestion; diode in the light wiring.

[kit of bits]

I normally work on 1950’s cars these alternator things are a bit modern
I’m thinking alternator has a problem feeding the warning light, back feeding the coil?
D

[Oneball]

What’s the ignition system?

I’ve had this with MSD type ones.

[kit of bits]

Just a minispares S dizzy with points..
D

[Andrew1967]

Not sure if this is of any help but I had an issue a couple of times with the alternator diode in my Pug 306 diesel a while back.

The diode failed and the ignition light stayed on and drained the battery.

I had to jump start it to get it home from work and from memory I think I had to stall it once home as it wouldn't turn off.

Replaced the diode and it was all good.