Monidal Starter and Solonoid Confusion

I had the same problem with an '84 Mondial QV that I owned. What I discovered was that the ground wire from the battery to the chassis was running through an on/off switch, which was completely corroded. Also, the negative terminal cable was not in great shape, and the contact point on the chassis was badly corroded also. I removed the old cable and got rid of the switch altogether. Cleaned up the connection on the chassis and negative battery terminal, put in a new cable, and most of the problems cleared up. Also changed the grounding strap from engine to chassis, which helped as well.

More times than not, intermittent electrical problems like that are the result of a bad ground. It's always the place to start. Something else to consider is the fuseblock. The Mondial fuseblock is notorious for problems. You might want to check the wiring diagram and think about wiring the starter relay around the fuseblock.

Hope that helps.

 

Don't have a US Mondial3.2 wiring diagram to check, but:

1. With certainty (if the wiring harness is unmodified), the white (B) wire should be connected to terminal 50 on the solenoid (this is the line that goes +12V when you have the key in Pos III to request starting), and

2. with less certainty, the white/blue (BL) wire should be connected to terminal 15a (this wire goes +12V when/if the solenoid actually engages -- i.e., the piston inside the solenoid moves).

Can you please describe the number of wires and wire colors that you have and the terminal numbers marked on the solenoid.

 

Do you have the records on the car? Could there be an old alarm or recovery system lurking somewhere that is blocking power to the solenoid?

You might want to check that voltage is getting to the solenoid before concluding it's bad. (Or just check it on a 12v source.)

 

I had 2 mondials, both suffered the same intermitent non start click problems, both cured by fitting a relay right closeup to the starter, that boosted the slight power loss in the main cables and it fired every time for years afterwards,
js

 

Could you post where you got the $30 solenoid? Have a crapped out starter myself, dunno for
sure what the problem is, but would like to have a source, if needed.
Thx

 

Just a casual rambling opinion:
It seems that over the years the voltage delivered to the solenoid drops, and/or (I think likely) the requirement for power to the solenoid to get it to fire goes up in our particular solenoid/starter combination. Many attribute this to the long distance to the battery and the switch. The already mentioned placing of a relay (which needs less juice to fire) near the starter enables the use of the larger amperage main cable to deliver power to the starter and the solenoid. I think this is the most cost efficient.
Something related is that some cars (certainly mine did) have a reluctaqnce to start when hot, again I think this occurs due to the above worsened by the heat soaking of the starter solenoid due to it's unfortunate location.
I am trying the high torque new technology starter (yes, it's Japanese ) now available that seems to require less juice to fire and turn the engine over. Using the original wiring, it has started after hours of driving in 100 degree plus weather here in Texas. Now, obviously time will tell but right now it seems promising. Since I want to use my car on long trips, I need the confidence that it will start every time, and this seems to be a good reasonably priced solution. So far so good, and we'll see after a year or so.

 

I had an Alfetta that had solenoid issues. Just dismounting it and cleaning it made a world of difference. The mounting location not only exposes it to heat, but to grease, oil, and road grime too.


In terms of connections:
A solenoid is essentially a big relay, allowing a small current to switch a big one.
(On some Italian cars, the solenoid also pushes the starter gear into line with the flywheel teeth, while other designs use a separate Bendix gear to engage the starter when it turns.)

Electrically, a solenoid has two circuits: the circuit to operate the solenoid and the switch circuit the solenoid operates. The switch circuit switches the starter motor on or off.

The switch circuit will typically be a big fat red or black wire from the battery and/or alternator. The wire may run from the battery to the alt to the starter solenoid, or from the battery to the starter solenoid to the alternator. There's another fat wire to the starter itself, switched from the battery wire. That "short wire to the starter" is part of the switch circuit.

The operating circuit will have an operating lead from the key switch and a ground. The ground tends to be through the engine frame, so it might not be a wire at the solenoid.

A picture of the solenoid might help people identify the connections. But the "slide on connector" sounds like it might be the operating circuit.

The operating circuit will be the "small current" part -- and the smaller wires. The starter is the heaviest current device in the car, so the switch circuit that operates it will have the fattest wires and connectors.

 

Maybe -- as I mentioned, some starter solenoid have a terminal 15a wire that should be connected to the large terminal that is connected to the starter motor (i.e., it goes +12V only when the starter motor is actually turning the flywheel/crankshaft). If connected to the large terminal connected to the "+" battery terminal, it would be +12V all the time (= not good).

But can you please back up and give more description about what you are doing. Are you talking about the cylindrically-shaped solenoid mounted on the starter itself (that also physically moves the pinion gear), or are you talking about an added (non-stock) solenoid switch (like one that would be mounted on the inside front fender liner of a 1950~60's automobile)?

If it is the cylindrically-shaped solenoid on the starter -- what are the colors of the two small wires, and are there any terminal numbers shown on the solenoid itself for the small wire connections?

 

OK -- yes, the euro model (no Lambda) is simpler.

 

From the parts catalogs on Ricambi, it looks like your connections are on one end of the cylinder. On one side you have a large wire to the starter. On the other, you have two wires on a common post -- one from the battery, one to the alternator. In the middle, you have the operating wire. Ground would be through the engine frame.

You should have three total connections: two bolts and a smaller connector (probably a blade connector). The smaller connector is the primary. With voltage on that and the frame grounded, the two bolts should form a connection between them. Inactive, the two bolts should be isolated from each other.

Best guess from the online docs.

If it was miswired, I'd guess you'd know in a hurry. Putting either the alternator or battery wire in common with the starter wire and your starter would be running all the time. (Either all the time period, or all the time the alternator was supplying current.)

 

The wire to the starter is the starter power. When there's power on that wire, the starter runs. If you hook that straight to the alternator, then the starter motor would be spinning whenever the alternator was providing power. You don't want the starter motor running when the engine is already running, even if the solenoid isn't pushing the starter pinion inline with the flywheel.

The solenoid is a relay switch. The two threaded posts connect together when the solenoid is active ... when you want the starter to run: only when starting. So you hook the starter to one side and your power sources to the other.

The short wire to the starter should be by itself. It's the wire that the solenoid is switching power to.

You want the alternator connected to the battery, so the alternator can charge the battery when the car is running --- after the starter is done. And so either the alternator or battery can provide power to the rest of the car -- ignition, lights, etc.

The reason they run the wires this way is that the wire from the battery to the starter is larger than the wire the alternator needs, and they only want to run one fat wire up to the battery. So the big fat wire to the battery carries the gawdawful current from the battery to the starter when starting (solenoid switched on), then after the engine is running (solenoid and starter switched off), the same wire carries the lesser current from the alternator back to the battery to recharge it. And they only need to add a short cable from the alternator to the battery cable at the starter solenoid.

The parts catalog picture doesn't make that clear, but the wiring diagram would. (The parts catalog is an "exploded view" -- with the wires backed away from their mounting points, trying to show 3D relationships on a 2D diagram.)

The 328 is wired the same way. I'd guess that most of the mid engine Ferraris are. On a 328, the battery wire is 35mm^2 (2AWG, up to 181 Amps) while the alternator wire is only 16mm^2 (5AWG, 118 A). The wire to operate the solenoid is a measly 2.5mm^2 (13AWG, 35 A).

But in terms of testing the solenoid; the solenoid should operate when there's 12 volts at the little connector, and the shell of the solenoid (where it bolts to the starter) is grounded. When the solenoid operates, the two threaded posts should have continuity between them. When the solenoid is inactive, the two threaded posts should be disconnected from each other.

For the wiring itself, the battery wire is connected to the battery, and will have power all the time the battery is connected. (And will carry enough current to push a car -- do NOT let that wire touch ground. It might be "only" 12 V, but there's enough amps to melt a wrench. Your battery should be disconnected whenever you're fiddling with those connections. Think of that wire as the car's "third rail".) The alternator wire will provide power when the car is running, and should be connected to the battery wire by being mounted on the same post at the solenoid.

The thin wire should have power when the key is in "start" position. That's the wire that tells the engine to start.

When you turn the key to start, the thin wire activates the solenoid. The solenoid connects the battery (and alternator) to the starter, and the starter motor turns. When the engine starts, you let the key return to "on", the thin wire has no voltage, the solenoid deactivates and the starter motor stops. The alternator then runs power back to the battery to recharge it and to run the car.

Wiring across a switch (or relay) is a common beginner mistake with wiring. My father made that mistake with outdoor xmas lights in the '60s, and thought there was a thunderstorm from the resulting blue flash. I'd last made that mistake in 2nd grade ... and it took them a week to restore power to that wing of the school.

And that was just piddling wall power -- 15 A or so. A car's starter is ten times the current. Getting it wrong would make really bad things happen.

 

A wiring diagram might help. You need to trace the solenoid operating wire from the key to the solenoid. It will pass through several connectors between the dash and the engine bay. (Likely one at the dash, one leading to the rear of the car, one at the engine bay firewall, etc.)

The odds are that one of the connectors has a bad pin. It might have gotten corroded, it could have gotten dirty and then heated (From the resistance) and melted the plastic shell enough to get the pin out of alignment.

But it's probably one of those connectors.

Adding a relay at the starter solenoid (a relay for the relay) is just a work-around. The basic problem is a bad connection. You need to check the connectors.