456 GT won't turn over.

Possible dead spot on starter / failing starter?

Corroded connections in the starting circuit?

 

Could also be a bad CPS. Try a quick test: try starting. If it fails, put it in sixth, get out of the car, push it forward or back about 30 cm, then try starting it again.

 

Bad starter solenoid or bad connections at starter

 

I have (fortunately) no such experience with the 456 GT but did have a similar problem with another brand late 90's car. It would just click and not even try to start. Would happen outside, not in the garage. In the end it turned out to be one corroded connection between the starter and battery, in the firewall. A 6,- euro part from the official dealer.

Of course the suggested connections and crank position sensor could also be the cause of the starter not doing it's job. What happens to other electrical items when you try to start? Nothing? Or do lights go out on the dash and interior? In my case everything dimmed seriously when trying to start.

Cheers,

Pekka T.
Fin.

 

Fit some temporary cables to the solenoid and the starter positive connection. Measure the voltage when you press the atarter, this will tell you if solenoid or starter.

 

I intermittently have the same problem. I have installed temporary wires so I can check voltages- when it happens I don't have enough volts at the solenoid. By the time I got the multimeter on the ignition switch the car started fine. The joys of fixing intermittent problems!

Mine does have an immobiliser fitted, so it is a possible culprit. I wish I didn't have to have it, but my insurance company demanded it.

The problem only happens when I have just used the car and left it for a few minutes. If I leave it for long enough to cool down it starts again. I did go as far as fitting a relay- which worked perfectly for a while and then didn't disengage- I ended up with 5V on the control line and the starter stayed engaged and I killed it. To stop that happening again I have put an indicator light on the solenoid control so I know it is de-energised (and energised too, for that matter).

This problem has persisted through two professionals looking at it and now a new starter. I have pretty much given up on the professional route- they just are not well-tuned to go after intermittent problems. I just have to harden up- I have worked on cars for a long time now, but do find the 456 intimidating, and really hate the lack of a decent wiring diagram.

I am out of action for a while, but my intended path is to
1) check the immobiliser- it is mounted inside the car above the fusebox. Maybe it gets hot or? I could disable the starter function for a while and see if things came right.
2) dissect the relay that caused problems to see if there was anything wrong with it. I admit is was a 'special' relay in that it was for a alfa selespeed pump. I chose it because it was rated at high amps, but maybe it operates in a way I don't understand. This failure could be my fault for trying too hard.
3) check the voltage at the ignition switch if I can make the problem appear again.
4) try to follow the (white) wire from the ignition switch to where it goes through the firewall. It isn't impossible there is a connector in there that is unhappy.
4) wire in a new relay- keep an eye on the solenoid feed with the indicator light. If for some reason it floats high, I might install a pull-down resistor. When it 'went high' (+5V) last time, it had no current capacity- it dropped straight down with any load (unfortunately the relay wasn't enough).

I really like the idea of an ignition relay- blowed if I know what went wrong last time.

But all of that has to wait until I can crawl under the car.

So, not a lot of help, but maybe we have a similar issue. I will report back in when/if I find anything.

Good luck!

Phil

 

It's not an immobilizer issue. The problem is a voltage drop to the starter motor when the temperature increases. It's a fairly simple fix. An aux start relay needs to be fitted. That is, the activator wire to the starter will activate a relay and the relay will provide full voltage to the starter motor. The problem is, the activator wire to the starter is also used as a ground source for the Ecu. So you need to fit a resistor from the activator to ground as well. That way the circuit will be still given a resisted ground and when activate to start, will trigger the relay to start. I've done this with BMW's and other vehicles that suffer with the same problem. It's a real pain in the a$$ when it happens. Do this, and you'll never have a problem again.

 

I'm sold on the relay idea. That is why I tried it- and it worked fine until the starter stayed engaged.

Could you explain more about how the solenoid wire is associated with the ECU?

The resistor should be between the control (input) wire to the relay and ground, correct?

This is where all my experience with analogue cars falls short.

And what size/wattage resistor should I use? This is effectively a pull-down resistor- right?

I really wish I had a wiring diagram. I found a schematic for the 456M, but amazingly I couldn't find the starter motor on it.

It still seems to me that there has to be resistance somewhere- I agree it is heat sensitive - to cause this. Or is just the starter taking more load? That said, a relay would still be the best option, and take the load off the hideously expensive ignition switch.

One thing I have done is wire in a temporary led indicator light for when the solenoid is energised. So I shouldn't leave another starter engaged.

Sorry to ramble- but I would really like to know the tie up between the solenoid wire and the ECU. And I would really like to fix this once and for all.

Thanks,

Phil

 

Image Unavailable, Please Login Hi,

I thought I should update this thread. I had intermittent issues with my 456 not wanting to turn over when warm. In the end I have decided it was an immobiliser issue- the immobiliser was wired to break the starter circuit as well as the fuel pumps and the immobiliser wires were simply too long and too thin resulting in enough voltage drop to mean the starter wouldn't work when the engine was hot. I simulated this by disconnecting the immobilser. I hate immobilisers, but my insurance company demands one...

Anyway, if I can work out how to attach an image, I will show my solution. I installed a starter relay (I used a high-current Alfa Romeo Selespeed pump relay- but I suspect this was unnecessary overkill). There is one 'trick for young players' and that is that the starter output from the ignition switch splits - a thick white wire wire goes to the starter solenoid, while a thin white wire goes who-knows-where. The who-knows-where wire floated at around 5-6V with the car running, which was enough to keep a relay engaged (and therefore the starter engaged) so I had to change my original solution to fix this.

I came up with the attached solution after discussions with an electrical engineer (and car guy). Minimal changes to the car, can revert to standard by changing one connector and no extra components like pull-down resistors. A year later, no issues at all. I admit I still have an indicator light on the starter wire so a) I know when it is powered up and b) I know that it doesn't stay powered up. I'm almost confident enough to remove that now...

Hopefully someone finds this useful.

Cheers,

Phil

 

Nice schematic Phil; thanks for the info! How did you bypass the immo for the fuel pumps, etc.?

 

Is his IMMO stock ferrari or aftermarket?

 

The immobiliser is aftermarket. I didn't deactivate it- it still works on the fuel pumps and starter circuit with the diagram above- so my insurance company should still be happy. All it does is break the wire to the starter and different wires to the fuel pumps- so it is a line of relays. The relays in the immobiliser are rated high enough- it was the wires and lengths of wires used that made it marginal when the car was warm- imho, it is never a good sign when you can feel wires get hot. To diagnose the problem I did away with the immobiliser on the starter circuit (reinstated a wire where the dotted lines are in the diagram above) and then it cranked fine.

Putting a starter relay in seems like a good idea anyway- it is a long way to the starter from the ignition switch on my right hand drive car, (the wire feeds over to the left hand side, then through the firewall, and then back to the right to get to the starter) whereas I mounted the starter relay in the engine bay above the starter so as to be accessible and fed it with thick wires. Also, I'm guessing/hoping the somewhat expensive ignition switch might last longer now that it only has to cope with milliamps instead of amps.

Anyway, I'm sure this isn't the only way to put a relay in, but would thought I would share a solution that works for me and that I think is pretty tidy.

Cheers,

Phil