Seat Belt/Door Open Buzzer Wiring (USA, Canada, Japan)

Sounds like you have a solid piece of wire instead of a buzzer unit or diode

Not 100% sure, but since the buzzer unit has a dual function, this could mean that your car won't have a self test for the brake warning light on engine startup. Looking at the wiring diagrams, on a normal car, when you crank the engine, the [(!)] light should be illuminated by a relay in the buzzer unit.

If you find (in the future), a brown-white wire joined to a white-black wire with a non-OEM splice under your dashboard, this might be your "buzzer unit"

 

(P.S.) On some cars, the [(!)] light is also the handbrake light. If you do decide to test the brake warning light function of your buzzer unit, release the handbrake before cranking the engine (with wheels chocked, and gearbox in neutral, of course)

 

Baffling. I still don't know how your car is set up.

My brake warning light goes out before the engine light, but that's the only difference in that respect. Like the wiring diagrams, my brake warning light seems directly linked to the ignition key being in start.

 

Here's a 5.2 diagram (Teves brakes*), showing the buzzer unit "06625" in the bottom left hand corner.

Teves Wiring Diagram (5.2 Motronics)

When the ignition key "03500" is put to start, battery power is provided to pin 8 of the buzzer unit which energises the relay coil in the buzzer unit. This puts an earth on pin 6, which provides an earth for the [(!)] light (via splice 30051)

This particular diagram doesn't show the door open circuits. The buzzer unit is found in 4 or 5 of the Ferrari wiring diagrams, so that's why I was keen to sort out the wire colours.

*I didn't have enough room to add the buzzer circuit to my Bosch brake diagram.

You may yet have a buzzer unit, but it appears the diode for the door lights is shorted causing both lights to come one when one door is opened.

 

I see it's a plunger type switch (rather than a lever type microswitch). It may be possible to adjust it using the large mounting bolt. If you can move the switch a bit higher relative to the latch assembly, this will depress the switch sooner when you close the engine lid (causing the required "open circuit").

There may be gunk in the switch. If you can remove the switch and drown it in solvent and turn it upside down and shake the excess out, then let it thoroughly dry (then add a bit of lubricant to the plunger, as there is metal to metal contact). My switch is pretty rough feeling. I need to add some lubricant.

 

Slightly off-topic, but does anyone know if the turn indications hyperflash and the clicking sound disappear completely if the turn signal acoustic repeater is removed from its holder? Or does the nearby hazard/turn module still provide some sound. I don't know if anyone has tried removing it because they think the turn indication sound is too loud.

I'm working on a F355 hazard/turn system faultfinding tutorial. In theory, a faulty acoustic repeater may cause hyperflashing because it's changing the indicator circuit resistance.

 

Thanks, Roth. Unfortunately this means we don't know where the power for the buzzer comes from.

Given the number of wires going to the buzzer module, there is plenty of room for a power wire.

3 wires for brake warning light (relay power, signal in and dedicated(?) earth)
2 wires for L/R doors
1 wires for seat belt
1 wire for power.

The blue wire on pin 3 may indicate ignition key power in, but we don't know the fuse number (if there is one) or which relay is used. Also, there is an unknown additional wire on pin "1" (driver's door open)

 

OK... .Latest theory on the buzzer circuit:

On cars with USA/Canada/Japan seat belt/door open buzzer modules, there is no diode (so both door lights go on when one door is open as per Paul's description). Both left and right door open switches are attached to only one pin on the buzzer (i.e. pin 1, hence the two wires in the photograph).

On cars without buzzers, but smaller modules, the left and right door open switches are connected to the module on different pins (i.e. pin 1 and pin 2). A diode sits between these pins, hence opening the passenger door does not put on the driver's door light.
These smaller modules have no pins/wires for power, but this is ok, because the buzzer is not active. I'll implement this theory in my diagrams shortly.

Thanks for all the inputs.

Cheers
Ian.

 

Latest plug pinout for USA/Can/Jap Door, Seatbelt Buzzer and Brake Warning Test Indication Module:

The plug has a non-standard numbering system with the even numbered pins on one horizontal row and the odd numbered pins on the other horizontal row. 1, 3, 5, 7 and 2, 4, 6, 8.

Pin 1: White-black wire - linked to passenger's "door open" switch and Brown-white wire - linked to driver's "door open" switch
Pin 3: Blue wire (possibly ignition power)
Pin 5: Black wire - earth. Related to brake warning light test during engine start and possibly a general earth for the buzzer)
Pin 7: (no pin on module, no wire)

Pin 2: Yellow-blue wire - input from seat belt
Pin 4: Pink-yellow wire - output to seat belt warning light in instrument binnacle
Pin 6: Pink wire - brake warning input wire
Pin 8: White wire - related to brake warning light test during engine start (power wire but only during engine start)

2.7 Wiring Diagram

5.2 Wiring Diagram