456GT Weird startup issue

I would start with a battery and or charging issue. Easy to have diagnosed at local autoparts store. Or multimeter if you have one and know how to use it.

Then starter motor and electrical lines between battery and starter motor.

 

You got a new starter? Why? What Lead up to getting new one? How long this no start situation?

 

Check cable connections at battery. alternator and starter since they were replaced. Suspect starter relay next. Never replaced that so I do not know where it is. FBB is on correct path. Why the new starter? Any other work done? Were parts new or rebuilt? Suspect rebuilt parts.

 

Assuming there is no immobiliser system fitted to your car, the circuit will be fairly basic. There may not even be a starter relay.

I guess the only way to find out is by doing continuity checks between the ignition and the starter motor.

 

Note that the 456M has both a starter relay and battery charger start inhibit relay. The 456M start inhibit relay is mounted in a relay socket with a built-in fuse (above the main relay panel, I believe).
One of these:

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I think only the 456GTA (non-M) car has this type of fuse/micro relay holder. The gated car doesn't have these.
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I'd imagine these are to inhibit start if the automatic gearbox is not set up properly for start.

Anyway, look at the base of the steering column shroud. There will be a connector with some large gauge wires on it. Disconnect the connector and (most-likely) there will be a white wire. This will be the starter wire. Do continuity checks between this and the small connector on the starter. If there is continuity, there is no relay in the system.

 

I did not think about immobilizer as my car does not have that but yes, it could be related to an anti-theft circuit if equipped.

 

Aftermarket immobilisers are probably one of the main causes of no starts on old cars. There may be an aftermarket start relay fitted.

 

Ian- The Zivan charger was optional, so that relay may only be on those with that option.

 

Here's a closeup of these type relays (on the 456M):

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The weird thing is, the fuses next to these relays aren't necessarily related to those relays. e.g. the rear cabin cigar lighter fuse is in the same holder as the RH inertia relay.

Sorry for the thread creep.

 

The OEM immobiliser is only found on the cars with Motronic 5.2 engine management systems. I thought the 456's only switched to the 5.2 system later in production.

Do you recognise any of these components?

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... especially the Ferrari key fob. You should have two black fobs and one red Master fob.

 

The Immobiliser on the 456M is wired into the starter relay. I'm not sure about the 456GT. I'm also not sure what part of the system would be sensitive to heat.

 

Very possible

 

You would have to find some kind of manual or schematic for the DEFA alarm to see how it interfaces with your car. It looks like DEFA is still in business, but I doubt they would have old manuals hanging around(?). You can only ask.

https://www.defa.com/defa-security-tracking/

Looks like it's an Norwegian company.

Or, if you can find a central ECU, try Googling the part number. Also look for non-OEM wiring coming from the ignition or relay panel. Does it have a flashing LED? Maybe you could trace the wiring for that to an ECU?

You may only need a new start relay (if it has one) ... not a whole alarm system.

 

Note that your DEFA system may only be an alarm system, not an immobiliser. i.e. it may only have glass breakage sensors, jacking (level) sensors and forced entry detection on the doors.

That means we will have to look elsewhere for a solution.

 

If it were mine I would strip it out and repair any wires. They probably used line taps but I have seen ugly hacks for security aftermarket installs.

 

Yep, that's why I mentioned it.

Just a wild guess, but I'd say you're in Oslo

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I'll have to start thinking about "plan B" if your alarm is just an alarm.

Unfortunately, the probably may be hard to identify as the car recovers so quickly.

By the time you've set up your test equipment, the problem may have already gone.