Headlights & Instrument Lights - Intermittent

Are you sure the headlights go out with the running and instrument lights?

Another place to look is the relay panel connectors.
See if you have a burnt plastic shell.

I had the intermittent on the instrument lights and running lights on my GTS, and it came back to a bad connection on connector J pin 8.
Common problem on US 328s: there are two wires on that pin, so when you stuff the board back into place, it can pull on the connector, leaving a partial contact.
When the current goes up, it heats, and can toast the plastic connector shell, leading to an intermittent.
I'd thump the dash to get it back as a temporary, before I got the connector shell replaced.

A confusion on these cars is the translation from Italian to English.
There are two systems translated as "parking lights", but with two different names in Italian.
The console switch turns on parking lights -- one bulb per corner, for lighting the corners when parked.
The stalk operates the running lights -- multiple bulbs per corner, dash lights, etc.
The systems are connected through oddball relay "o".

The headlamps are not involved, but the fog lights are.

If the J8 connector goes off, you lose the power from fuse 16, and the running lights revert to just the parking lights.



If the headlight bulbs really are going out as well, it might point to another issue.
But look at the relay board connections. The 328 is known for having poor connectors there.

Intermittent wiring connections can be tricky to find.

All you can do is get into the wiring and start shaking things, trying to replicate the problem while the car is in the garage.

 

"Generally"? You have to be more certain about this -- do they: 1) always stay up, 2) sometimes stay up and sometimes go down, or 3) always go down?

 

Check your grounds. (Check for rust spots, etc.)

The running/instrument lights and the headlights are completely different circuits.
For that matter, the right and left headlamps run different circuits.

Did you notice anything else dropping out, such as the gauge readings?
That might point to a power connection to the relay board.

It'll be hard to diagnose an intermittent problem based on two year old memories.
You should probably get under the dash in the garage and start wiggling wires.

If the problem is as you describe, then take a wiring diagram and check the stalk switch ---
--- carefully.
They're fragile and very difficult to replace.

 

Had a similar goof with my 308 QV, a while back. Turned out to be the instrument light rheostat. It started out as an intermittent problem, triggered by road-jitter, the progressed to full-on no-worky-worky. I'll admit I "fixed" the bad rheostat dimmer by simply bypassing it with a short length of wire. Should probably replace it, (or at least add an in-line fuse to my jumper connection) but I hadn't even thought about it since it happened (while on an epic road-trip).

 

As I recall, it was just the instrument lights.

 

Had a look at your 328 wiring diagram Fig 6 (which you can download from here: ferrari documentation), and, unfortunately, if the stalk switch was causing the headlights, running lights, and dash lights to go out, I believe it should also cause the headlight pods to lower. Since you report that that is not happening, I'd be more fearful that the fault is on the fuse-relay panel PCBA itself.

One test that you could do is just hook a jumper wire from a good ground to the small green (V) wire in the x white connector (the metal back end of the female terminal holding the green wire is sort of accessible as a place to connect the jumper with everything plugged in). That will simulate a closed stalk knob switch so the exterior lights should come "on". If you still have the same trouble with that jumper in place when driving around, that would confirm that it isn't bad behavior at the stalk knob causing the issue.