X16XE still runs when keys out of ignition

[Dan Stanley]

My X16XE engined nova has been running fine for over a year, yet on the way home the other day it developed this problem. Once the engine has been started, you can turn the ignition off with the key and the engine still carries on running. For some reason the switched lives are staying live, so the engine and the head unit etc are on.
If you kill the engine by pulling out the fuse to the ECU then the switched lives go dead with the ignition off. Its as though something is back feeding the switched live circuit, but only when the engine is running.
The car has been running fine, so I doubt its a 'wired up the engine/ECU wrong' situation. Im hoping a component or relay has failed somewhere. Has anyone had a similar problem? Or knows of any common causes?
I dont want to use the car as it obviously has a fault somewhere.

[Southie]

Have a look at your ignition wiring as by the sounds of it your getting a permanent live.

[Dan Stanley]

Its strange how it only has this problem when the engine is running. If you turn the ignition on but dont start the engine then the ignition switched lives turn on and off (as normal) when the ignition turns on and off. I wonder if this points to it being a circuit or component that has a permanent supply, a switched supply and only operates when the engine is running? ECU perhaps?

[Riggy]

sounds like the black cap on the end of the barrel , sticking open when you turn it too postion 3 fo starting

[TonySR]

Check all earths, I had this on a mk3 xr3i I used to own. Cleaned all the earths up and it never did it again.

[Dan Stanley]

Had another play around with it today. I disconnected the ignition barrel By pulling off the big black plug) when then car was running and it still ran. Also tried disconnecting the battery and the car still ran. Finally tried disconnecting the battery positive from the alternator and pulling the alternator belt off. This seemed to sort it, so I'll be off to buy a second hand alternator tomorrow.