Ferrari 412 K Jet Air Flow Sensor Electrical Connector

That's the normal setup: whenever the airflow sensor is shut (i.e the engine does not breath air), this switch will deactivate the relay pumps, which is meant to avoid the high flow k-jet pumps to split litres of gasoline all over the place after an accident.

This safety mechanism induces additional complexity in the system that can be troublesome: during startup the engine does not breath air, so whenever the engine is cold, the thermo-time switch will override the safety mechanism and activate the pumps for up to 7~12 seconds. Then what happens when you want to crank the engine when it's hot? The thermo-time switch does not operate so we have to rely on the accumulators that are holding fuel and pressure for roughly one hour.

All in all if your thermo-time switch is bad or the accumulator are leaky, or if the seals of the valve pressure regulator are shot you will not be in a position to crank the engine, and your only solution will be to force the pump to operate (= disconnect the green plug you've just discovered).

 

By the way, where did you get this red headed 412? There are not so many that I know of. The two I've come across would definitively not need an engine out.

 

No paint on the 412: unlike the others that had black wrinkle paint the 412 had unpainted heads. So if you paint the head it will not be original either.

My brother had such a 412 with red heads. He got it from a friend who had two grey manual 412 and who decided that both would look better with painted heads. He finally came to the conclusion that having two identical 412 was hard to justify, so sold one to my brother.

Red heads can be nice depending on the car colour combo: a grey/black 412 with red interior can be nice "red headed". I would not say so for other colours.

 

I don't think anybody shared these diagrams here and that's really frustrating: once the electricity is sorted out these cars are a real pleasure.

So no free sources for the 412 electrical diagram... Unfortunately the diagram you can buy will be "factory quality" at best, that is to say nowhere near what Paul Bennet has been offering for the 400.

Rear trunk mechanism could be found in old Cadillacs (there is a thread on the subject), but no idea regarding proper substitutes for the actuators used on the bonnet and fuel cap.

 

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This is for free !! The internal diagram for your fuse boards. Its in mirror view en split in 2 for more clearness. Happy New Year and enjoy you cars in 2022.

 

A reprint of the 412 wiring diagram is still available from Maranello Concessionaires for a fairly reasonable IMO price:

https://www.ferrariparts.co.uk/part/ferrari/95990850?id=65064

 

No, I don't have one to scan, and I don't recall anyone here ever saying that they have it in pdf format (nor offering to share it). If you do get a pdf copy, please share it with us.

 

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I have struggled with the three push buttons for hood, trunk and fuel cap. The problem can be the switch; contacts burn out. Switches are available but getting pricey. More often thew electrical connector on bottom of switch has bad contacts that can be cleaned and reinstalled. Also, check contacts on the solenoid under the hood if you have been doing work back there; its close to firewall behind the wiper levers. Mine all working regularly now.
Ken

 

Fuel pumps should run with starter. Residual pressure is not expected to start car.