Evening all

So yesterday my 300tdi mastered a new party trick…

Starts fine, runs fine & stops fine…when the lifts are off but if my lights are on it continues to run even after the key has been removed from the ignition ….naturally I’m concerned this could produce further buggeration or even if I don’t rectify it.

I saw a mention that another thread touched on this but haven’t been able to find it.

My gut says ignition switch fault but can anyone share their experience of this please?

Thanks G

I have the same issue on my L322 MY2005 but only on main beam. I mentioned it a few weeks ago so it may be that post that you saw.

Try everything else and look for odd behaviour, indicators, hazards, brake lights - making them all operate with lights on, horn etc with someone outside looking for dim things or stuff coming on when you haven't commanded.

There are various earth points and your problem could be either:-

One of the earths is shared by the lights and something going to the immobiliser ecu, or to the fuel shut off solenoid. A nuisance. Other odd behaviour would support that theory.

Chafing in the wiring loom anywhere from the ignition and column switches onwards. That's where the fire risk comes in, but possibly only when it's got power.

I'm tempted to say side light filament touching brake light filament but with such a basic setup, the brake pedal switch *should* prevent that.

is it fitted with a trailer socket has the screen leaked recently (headers) ,dim dip relay ,column switch checked etc etc more info please

It's running because there is a voltage on the cut-out solenoid (STC3254).

Using a volt meter.
With the engine and light off - check the voltage at the solenoid (use the engine as ground).
Ignition on - check (should be 12V)
Sidelights on - check (still should be 12V)
Headlights on - 12V
Turn off the ignition and remove key - should be 0V (engine should stop).

If there is still 12V then turn lights to sidelight only.
If there is still 12V turn off side lights.

Start the engine and repeat ....

Check the earths on the bulkhead and the earth under the car near the gearbox, there should be a connection from the gearbox to the chassis and from there to Negative on the battery.

Let us know how you get on.