07 599 buttons on the backside of steering wheel inop

Do you know the part number of your steering wheel?

https://www.eurospares.co.uk/Ferrari/599/599_GTB_Fiorano_(USA)/PartDiagrams/0046/STEERING_CONTROL?ref=001

There seems to be quite a few different types. I was wondering if all of them have these backside buttons.

Here's an image of one kind of 599 steering wheel P/N 80843400

Image Unavailable, Please Login

I see horn wiring, engine start wiring and Manettino wiring but no special button wiring. It looks very similar to the 430 steering wheel, but I'm not sure if any of the 430's have those additional buttons you speak of.

I don't know if you are aware, but modern steering wheels have spiral ribbon cables to transfer most of the data from the steering wheel to the steering column. These are contained in devices like this:

Image Unavailable, Please Login

Image Unavailable, Please Login

Old fashioned clocksprings are not used.

Unfortunately, ribbon cables have a maximum number of wires (e.g. 12), so not all button/knob analog data can be transferred through the ribbon cable. The data has to be multiplexed (digitised). The Manettino settings (and I believe Start Button operation) are digitized. I don't know if your additional button data is digitised or use up several of the ribbon cable wires. The data is digitised by a box behind the manettino knob. You can see it with a yellow sticker on it in the first photo.

To be honest, I'm not sure how you'd go about electrically testing the buttons without a wiring diagram for the 599 steering wheel and lots of steering wheel disassembly.

Note that these ribbon cables can fail. Not a Ferrari, but you get the idea...

Image Unavailable, Please Login

 

If you do decide to do wiring checks (with an ohmmeter), that would be very useful for diagnosing other issues. I tried to make sense of the various wiring diagrams for the 430 steering wheel, but without being able to get my hands on an actual wheel, I couldn't resolve the confusion:

The red plug in my first photo has 8 pins, but it doesn't have enough pins for the airbag, too. The airbag wiring still goes through the "clockspring" (ribbon cable/"spiral contact") though (via a second plug). The wire colours change at the red plug before it goes into the clockspring adding to the confusion. The clockspring possibly has 10 or 12 slots (I don't know if the outer slots are used as these are often the first ones which get damaged through wear and tear). I assume the additional 599 buttons you have use two extra clockspring wires (unless the output signals go through the CAN Bus wires). The 599 and 612 have the same clockspring/spiral contact, but it was superseded by another clockspring which suits later cars, too.

On the car side of the clockspring (not the wheel side), there is a plug with 12 pins. There is a wire colour change there, too.

This the best I could make of the F430 wiring:

Image Unavailable, Please Login

The red box represents the red plug.
Quirks and features:
The 2 horn buttons only require one clockspring wire (for the signal out of the wheel).
CAN Bus has two wires.
There will be a power (IN) wire (not sure if this provides lighting or if there is a separate wire for this). This provides power for the horn, START and probably the manettino module.
Oddly, a red wire is earth (not power)

This may or may not help with your diagnosis.

 

I also noticed that your car has the LED lighting strip for rpm/redline. I wonder if this uses the CAN Bus/Manettino electronic module also.

 

Actually, after looking at your button photos, I'm wondering if the buttons are here in my photo....

Image Unavailable, Please Login

The wiring sheath close to the button is grey, but I can't see if it goes directly to the red plug or to the Manettino module.

 

Disregard my last post... The grey sheath that I saw is actually the grey metal frame of the wheel.

There does seem to be additional harnesses, going outboard, however...

Image Unavailable, Please Login

Here is a shot of a 430 Manettino/CAN Bus module.

Image Unavailable, Please Login

The horn wiring just passes straight through the module to the red spiral connector (signal not digitized). Hopefully the display mode buttons are the same on the 599 so you can do continuity checks. One wire on the red plug should be a ground.