Engine Still Running without Ignition Key! Ford Puma

[Teocali]

Looking for help with tracing an electrical fault.

At present when I remove the key the engine keeps running if:
1 – I have my foot on the brake, and
2 – I have headlight on

The engine will run indefinitely and all other electrics remain live.

Any guidance on how I trace this (assumed earth fault) would be greatly appreciated.

Taken me two weeks just to make it replicate the fault!

Thanks, Sam

[Penelope Stopit]

Yes I can fix it for you
Before we delve too deep, remove all the rear brake light bulbs and check if it's fixed

[S0 What]

Check as above, if the brakes lights are stop and tail and fitted incorrectly or a sigle pole bulb is used the brake light can feed the sidelights and vice versa, so if the lights are on the sidelight live can feed the brakes and back to the ign via the brake switch ?
Used to get it a fair bit on escorts (mainly diesels) where water gets into the rear lamps and cuases a similar short, it's the first place i would look followed by dimdip relay "IF" fitted (not sure what year your car is ? )

[Teocali]

Hmm....


Firstly thanks for the advice - I had ruled out fault brake lights due to them working and as they haven't been changed in the past 4 years.

However after removing brake lights the problem is cured. Brake lights back in - still cured.

Now suspecting it was due to rainwater....

Either way tricky to probe further as its not repeating.

Thanks again.

[Penelope Stopit]

Water is not the problem, corrosion caused by water may pass enough current to pull in a ignition relay, if you found water with no corrosion that alone will not cause the fault
Bulbs fitted incorrectly or wrong bulbs fitted could cause the problem, a bulb with a short across filaments could cause the problem and by removing the bulbs you have disturbed and removed the short inside one of the bulbs
Faulty tow bar electrics could cause the problem
A short between brake lights cable and tail lights cable in the rear loom could cause the problem
If you were me you would fit new rear bulbs and let time do its testing

[Teocali]

Just to follow up to say thank you...

New bulbs have stopped the issue - I do like a simple fix!

[Penelope Stopit]

Glad to help, your replying and updating has restored my faith in mankind