Porsche Enthusiasts Club Forum

Hi car has been garaged for 2 weeks. Took it for a run today and when I turned off ignition it kept running even with key removed.Had to pull coil leads to kill engine. All ignition lights stayed on so disconnected battery. Is this just a worn ignition barrel and if so where's the best place to buy one and a new key? Thanks for looking
.

Could be a bad ignition switch, but also could be a bad alternator.

When you turn on the ignition does the battery light illuminate? When you start the car does it go out? and when you turn the engine off does it light up again for a second and then go out?

I have known 928's (as well as 944's and air cooled 911's) to continue running if either the battery light bulb is missing/faulty as the alternator can not discharge into the bulb and therefore tries to discharge into the ignition wire, which keeps it energised and so keeps the engine running, which in turn keeps the alternator charging and trying to discharge.. a vicious circle that keeps the engine running until it is stalled.

Thanks John will check it out at weekend and post up the exact symptoms.this was the last run of the year before Sorn

Sorry Jon spelled your name wrong

No problem

Euan did you by any chance use the heated rear window switch on your trip before you tried to shut down engine?

By the way disconnecting battery while engine running risks damage to alternator. Safe way is to remove air filter and block air to MAF with your fist, or more easily just shove your foot on end of exhaust pipe!

I stopped the engine by pulling out the king leads on the 2 dizzy caps . Then I had to disconnect the battery as the ignition lights were still on with the key out. I don't think I had the rear screen on. I'll start it up again on Sunday and pay attention to what lights do what.Cheers

OK sorry missed that you pulled coil leads first (sounds dangerous for you though!).

Check that the defroster button isn't pushed in - if it sticks in this position the engine will run on.

..., weird ., but true

Ken

Thanks, heated screen was on, everything is ok now. Would never have known that in a million years. Thanks for your help guys.

Adrian brilliant as usual well done.

Elementary my dear Andrew. Heated screen is direct feed from battery, and is linked into ignition circuit.

Now the issue is why Euan's screen was on. Either the switch jammed in the "push for demist" position (it's jamming against trim which has distorted with age - just needs cutting away sliver so as not to jam), or the timed heater relay was sticking in on position. If it was the relay it should be replaced.

I'm blushing now Sean!

There,s loads of info re the rear defroster issue on Rennlist, probably the best 928 resource around !

Ken