78 308 GTS - Engine won't turn off

I've read several posts about 308's not shutting off when the key is turned off.. but none of them have the same symptoms that I'm experiencing with my 78 (US Spec) 308 GTS.
I should start off by saying that I recently installed a new blue-tooth retro Blaupunkt radio.
I had to splice a wire into the "ignition ON power wire".
After the install of the radio, the car ignition worked fine for a couple days (maybe a week), until one day I went to shut the car off and it continued running (even when I removed the key).
When I turn off the ignition (while its still running) somethings continue working but other things don't..
I noticed the A/C compressor disengages when I turn the key off, but the blinkers and fuel pump continue working.
When I stall the car with ignition OFF, the blinkers then stop working and fuel pump then shuts off (as it would if it shut off normally with the key).
I checked all wiring around the ignition (in case something came lose from radio install), but everything is well connected..
What am I missing? Is it possible that the "ignition power" wire I tied into split conductivity?

 

There have been quite a few similar posts on the FChat forums with similar issues (not only the 308). I suspect during the radio installation, you have spliced (or shorted) a live battery wire to an ignition key power wire.

Hopefully all the key powered systems on the car haven't tried to run through the radio wiring. Any burning smells or super hot wiring?

 

Disconnect the radio and try it.

 

Maybe there is some relay that is kept alive by the radio, a back EMF if you will. As stated above remove the spliced wire and if all goes back to normal perhaps putting in line a proper capacity diode in the radio supply wire might solve this problem. Just a WAG.

 

Start over with the hot wire for the radio and find a different existing wire to make the connection. On my vintage Ferrari I made the connection to the cigarette lighter which is fused and always on. That way I can listen to the radio without having to turn on the ignition switch.

 

Being in my 50's not as nimble as I once was.. This coming weekend I'll remove the seat and steering wheel and crawl back under the dash. I'll start with disconnecting the power wire and see if it fixes it.. I'll post back once I give it a try. Thanks for advice!

 

no burning smell or hot wiring to my knowledge.. I'm not going to run the car again until I disconnect power from radio and check if that fixes it.

 

Update: I disconnect all the power wiring that I had installed for the new radio, cross-over, and amp.. Car still won't shut-off..
Besides the radio install, while I was under the dash I noticed someone had un-plugged the door/key buzzer (so plugged that back in).
After hearing the buzzer noise, I can understand why someone unplugged it.. I'll keep it plugged in for that nostalgic feel of the car.
I had also disconnected the power antenna because the new radio has a different type of antenna and the antenna didn't work anyways.

I'm going to see if I can find a wiring diagram for a U.S. 78 308GTS and trace everything out.
Perhaps its a grounding issue somewhere?

If anyone has any other ideas of what to look for, let me know.
As mentioned in earlier post, some of the things I've noticed with the car not shutting off..
While car running, when I turn key off, car continues to run, however I notice the AC compressor clutch disengages (blower fans continue to run).
Blinkers and fuel pump also work while car running with key OFF.
As soon as I stall the car, the blinkers stop, blower fan shuts off, and fuel pump stops.

 

Are there any in the Owners Manual?

Sounds like a clue. I found a much later model diagram online, and the compressor clutch power seems to come directly off the ignition key. I'm still trying to figure out the blower circuit. It's the first time I've looked at a 308 wiring diagram. It's like looking for a needle in a haystack.

Maybe check behind the left hand fusebox (if the early cars have them)? That seems to have fuel pump, engine and blower fan power and lots of live wires running next to key power wires. The A, B, C fuse wiring may have issues (wild guess).

Have you updated your fusepanels?

 

Fuse panels are original.. and I don't have a owners manual..
I've seen colored wiring diagrams for sale, but not for my year.
I did put a new blinker relay in recently (same time I was doing radio).. I was able to find one that worked from local chain auto-parts store.
I contemplated ordering an exact replacement, but can't see how the one I'm using would cause the car to not shut off.

I'm thinking the power source at the ignition used for keeping car running is somehow being back fed from another power source when key turned off.
While the car is running, the power source is still there continuing to provide power to the fuel pump.
When I stall the car, the power source is eliminated so kills the fuel pump.. and car is completely off as when it would normally work with key.
This could take me a while to figure out!

 

Interesting. What stops when the engine stops turning? The alternator stops when the engine stops turning, but that is wired up to the battery, so I guess the phantom power source would still be there. On later Ferraris, the engine ECU(s) enable the fuel pump relay(s) when engine rpms are detected above a certain value. The 308 just needs key power as far as I can see.

Do you have an aftermarket engine management system? Also, do you have an aftermarket engine immobiliser fitted?

That's what I was hinting at in my earlier posts, but the fuel pump behaviour (EDIT) may be giving us something extra to work with.

 

Correction. Looking at the wiring diagram I have for the later 308, there is something called an airflow switch which controls power to the coil of a "start valve" relay. This "start valve" relay supplies power to the pump relay coil.

See this thread:

https://www.ferrarichat.com/forum/posts/143140742/

@Steve Magnusson if you're out there? Does airflow (induced by cranking of the engine) enable the pump?

 

He's got a carbed 308 = no "start valve" relay at all, and the fuel pump always runs with just the key "on" (if the Driver seat safety switch has been bypassed). The bottom line would be to measure the voltage at the top of fuses #1, 2, 3 = should be +12V with key "on", and 0V with key "off". If it is still +12V with the key "off", unplug the A (light blue) wire from the top of fuse #2 -- if the engine shuts off = strong sign the ignition switch is bad. If the engine doesn't shut off with the A (light blue) wire unplugged = I'd suspect something wacky with the alternator.

 

Might be a worn ignition switch. I had an airplane once that would not respond to the ignition switch, and when replaced, it solved the problem. Is there any way of testing it? Jumper it with some test cables and then disconnect each lead sequentially like the switch would do, if that is possible. Perhaps the switch can be rebuilt or repaired if it will disassemble.

 

I assume this fuse gets power directly from the ignition switch.

@jurkoj If you want to stop guessing, follow Steve's instructions... He's the guru

 

Funny you should say "driver seat safety switch has been bypassed".. I replace the carpeting while I was installing the new radio system, so I could run wiring under the carpet for rear speakers. I did notice there were several wires disconnected below the seat.. one set of wires were coming from the seat itself which were already disconnected (it came that way from the previous owner).. I didn't attempt to re-wire any of those wires, just left them as is.

I will test voltage on the top of the fuses as you mention and see what I have for voltage.. I may not be able to get to it this evening (working for a living gets in the way of the fun stuff!).

One last thing to mention... I did install a main battery Cut-Off switch (flaming river) which I put on the (-)negative side of the battery.
That was about a year ago..
I installed so I could easily disconnect the battery when the car sits for long periods of time.

I want to thank everyone for helping me with this problem!
I'm learning a lot about the car...
It is one of the most enjoyable cars I've driven and owned.

 

Do you have a wiring diagram for an early 308GTS (US spec)?
Could you share or sell a copy if you do have one?
I've been looking for one online and haven't had much luck.
thank you!

 

No. I was only able to find a later model diagram:

https://www.dropbox.com/t/uUU5y5YRctzcEPq5

It may help with some circuits, but, as Steve says, there are differences.

 

Exactly -- the large A (light blue) wire connects terminal 15 (+12V key "on") of the ignition switch to the top of fuse #2 (which is then bridged over to the tops of fuses #1 and #3).

Most have been bypassed by now ("jumped" to be in the always closed state). It's kind of a flaky switch design that detects the seat bottom deflection of the Driver's weight in the seat with the idea being, if the car goes upside down after a bad accident, the fuel pump shuts off even if the key is still "on". Number of people stranded when this flaky switch goes bad = many; number of people actually saved by this feature after an accident = probably zero . It's only on the later carbed US 308s, not the euro 308s.

The wiring diagram is in the back of your 150/78 OM -- you should get one (either an original or a good reprint) as some of the printed detail is quite small (especially on the schematic). This link will get you a (not great resolution) pdf scan of 150/78:
https://www.dropbox.com/scl/fi/spuk1t6hvllibxfi79uxk/MUM_308GtbGtsNorthAmerican-150_78.pdf?rlkey=p7fbhikcv5317sjyionlo4wj0&st=ooqpzsf1&dl=0

You can't contact them now (being August), but you could try MCP:
https://www.ferrariparts.co.uk
as they are the official older F part supplier, and used to have the Marparts OM reprints available at a very reasonable prices.