348 Wont Turn off by Key

Hi all, I have a 1995 348 Spider which seems to have developed an unusual fault in so much as at first, the radio & pod fans came back on, after key was removed (but then went off again after a few seconds) but this became more & more common, (and not going off at all) then in the later stage the engine wouldn't turn off when the key was removed either! so I had to stall it and use the battery isolator

Has anyone had this problem / can guide me in the the right direction? as I have had it into a performance specialist who has had it all over the winter only to ring me today to say he's at a loss and come & collect it!

We have tried the obvious such as faulty Ignition switch & Relay
So any ideas gratefully received !
Thanks
Dave UK

 

Having the same problem with my 328. No reading on any of my gauges or tact either. Click and dash lights work but I can pull out the key and it keeps running.

 

Hi, The process we have been through so far is the immobiliser has been bridged out, the Ignition key unit has been disconnected in case faulty (but still ran) the Ignition Relay was changed the radio was disconected but these didnt solve mine, I dont know if any of these may solve yours? Regards Dave

 

I'd think the problem would lie in the mechanical ignition mechanism. Save that...perhaps a bad ground is keeping a charge in the system? If the mechanicals (timing, etc) check out there's parasitic current draw somewhere...start at the fuse box to see if any obvious signs of corrosion/burn-through?

 

Did you check the wiring at the alternator

 

its a bad electric diedo in the alternator if you buy one from radio shack and put in line on the wire that powers up the alternator when you turn the key on problem will be fixed

 

Are there any Radio Shack's left? All closed down in my area. In my case, why would an alternator diode have anything to do with the gauges not registering?

 

Cause there's power flowing back from alternator keeping the car running but when you're turning ignition switch off it's turning may be the gauge cluster off but not the ignition to engine

 

I'm not trying to hijack the thread but since I've developed this engine continuing problem, the gauges don't work at all even with the ignition switch on so I am trying to figure out how anything with the alternator would cause this. Mine would seem to be a different problem/short somewhere.

 

Hi. I have the exact scenario now on a 348 (engine won’t shut off even when key out)...read the thread above. Wondering how this issue was ultimately resolved. I would appreciate any feedback. Thanks.

 

What are "pod fans"? One possible cause of your problem could be the alarm siren. Does your car have it and is it the type with its own rechargeable battery?

 

No it doesnt have it. What’s weird is even with the key out and ignition key harness disconnected, the power is still on. There is a short somewhere.

 

Then, obviously, it is somewhere downstream. I would suggest you first try with disconnecting the radio and any other accessories (if added) that are powered with the ignition "on", before going to the wires and relays.

 

For what it’s worth, many years ago I had the same problem with a Porsche 928. Someone told me to always go back to any aftermarket items such as alarm, stereo; in other words, things that were “f——d with” as he put it. Sure enough there was some wiring in the fuse box for an aftermarket alarm that was no longer on the car and disconnecting resolved problem. Not sure if any of this will translate here but good luck!

 

Thanks for your tips. I disconnected every accessory wiring tapped on the ignition key harness and even left the connectors apart. Something is still feeding power to the 15b line.

 

According to my quick look at the line 15b, it appears to go only to the ECU-s (Pins 27) and to the ignition coils through which it goes to the ignition modules. No relays are involved. It is possible that there is a fault in either one of the ECU-s or one of the ignition modules keeping (back feeding) the power to the line. Or there is a short in one of the ECU connectors or between its wires in the loom. I suggest that you first disconnect one of the ignition modules, start it briefly on 4 cylinders and see if you can then switch the engine off with the key. Then, depending on the result, connect the module back and check the other ignition module in the same way. Hopefully, this will tell you something. If this does not result in finding that one of the ignition modules is a culprit, do the same exercise by disconnecting the ECU-s one at a time. MAKE SURE YOU DISCONNECT THE BATTERY EACH TIME YOU DISCONNECT OR RECONNECT THE ECU-s. I would disconnect the battery even for the ignition modules, just in case.

 

Just an update. Removed and reinstalled both ecu’s, checked wiring harness for any issues and put Stabilant in all connectors. No change. What is alarming is the parasitic draw (measured in negative side of the battery) is 475 millivolts or 4.7 amps! Pulled all the fuses and relays in both step pad and under bonnet. No difference. Either the dash or the alternator would be the most likely culprit. That is the task ahead.

 

If the draw from the battery is 4.7 A, the battery would be flat overnight. How did you measure 475 mV and convert to (or measure) 4.7 A? I normally disconnect the positive or negative cable at the battery and insert the multimeter, set to amperes, in the "disconnection" and read the Amps or Milliamps directly. On the positive terminal of the battery, my 348 has, in addition to the very thick cable going to the alternator and starter motor, two fairly thick red cables that can separately be disconnected. If you have the same, you can separate the cables of the battery positive terminal (you will have three lines but the two red cables go to the same point) and check to with an ammeter whether the draw is through the cable to the alternator / starter motor or through either of the red cables. If it is through the red cables, then your alternator is not the culprit.

 

Sounds to me like a failed ignition switch. Similar failure to the one on my Lancia Beta. Battery draw, things wouldn’t turn off. Interestingly enough, running lights worked but headlights did not.

Replaced the ignition switch and everything worked perfectly.

 

The parasitic draw test was performed by using an ammeter in series between the disconnected neg cable and battery post. Also used a 1ohm/10 watt resistor (in series as above) to get mv readings.

Also the ignition switch was isolated with all 3 multiconnectors disconnected. Yet the power was still on.

Will check the thick wires as Miroljub suggested.

 

That's a huge current draw. Did you check it when you disconnected the ECU-s? If you find that the current draw is not through the alternator but through the red wires, you should do the current test with the ECU-s disconnected, one at a time,

 

I didn't think of it earlier - check the battery drain with the ABS fuses and relays disconnected. Do same with the AC fuse and relays. Time to remove the boot lining.