456M brethren: can someone help? It would save me $2,600

Logical idea. You might also try and isolate the other components from the panel and see where that gets you, especially if no donor panel comes up.

I get a real feeling of dread when 456s get fuses blowing for no obvious reason. I have seen more harness problems on them than I like.

 

I know there is a connector close to it but it may require removing the door panel to get to it. I don't recall where it is. I suspect there is a plug at the hvac box for the entire thing. Also, I don't recall, does the panel itself have more than 1 plug? Some of those components like the susp system etc have a plug for inputs and a plug for outputs. A little perusal of the diagram may pay off in less blind groping around.

 

Why not just return the new panel if the panel is not the problem?

 

Special order parts and electrical parts are non returnable. Parts departments don't really like being lending libraries either.

 

You can do it that way all year long or you can have a look at the diagram and have a little more efficient approach.

You seem to be focused on the ambient temp sensor. Is there a reason why?

 

It is downloadable somewhere. Do a search. I think Taz has referred to the source several times.

Finding electrical problems needs to be systematic to be productive.

 

Ok, I will write down what I am thinking out loud.

I am actually surprised the panel would be fused at 7.5 amps. Most of the things it controls draw more (AC clutch, fan motor). Those items will probably have their own fuse.
The panel itself will contain so little electronics that it will be drawing well under 1 amp. My conclusion, it or its fuse may normally be feeding something that draws more.

What does this panel feed? A relay for the AC clutch, a relay for the fan motor, and/or a current for fan motor control, and possibly the auxiliary water pump that these cars have for water flow through the heater matrix.
And perhaps that little waterpump may be the problem as that might be fed directly from the panel and not over a relay. Or perhaps there is a relay but the current comes from the same fuse as the panel (since the heater system is useless anyway without that little pump).

It is imho highly unlikely that such a board will short out and repeatedly manage to blow a 7.5 autofuse (which are very slow fuses). So it is more likely that something that the board controls is shorted, or something that uses the same fuse. This leaves the relays and the aux pump to check, and it is my suspicion it will be that pump.

I would not try another board in your car. In fact I would suggest the other way round, try yours in another car. This for two reasons. 1) there is always a small possibility that there is a problem in your car that caused the board to short - so a new board can be damaged just by attempting to use it. It is that why it is important to isolate the issue, especially make sure that any outputs of the board are not shorted in the car (measure the relay coils, etc).
and 2) if the fuse blows again with the second board, what and where is the problem? Is the problem in the car or have you caused a short in the new board? You will only know once that board is tested again in a known good car. And with either of the two possibilities, you will not have learned much more than you already know. And you're obviously better off trying your board in a known good vehicle.
Absent of that (it will be quite difficult to find someone willing I think!), your best option is to check everything on that fuse and outputs of the board.

And if you find it is the panel in the end: is it panel serviceable or is it a sealed unit? A simple short should be easy to find for a good electronic repairman.

 

Dave- I sent Ben Deetman the expanded section L for the 456M, so you can download it for free from ferraridatabase.com. Not sure it has what you want, but there is tons more info there than in the basic WSM section L. Like door panel schematics.

 

Clever boy! Right on with the logic. Ding ding ding! Cheers-

 

It is one of the most beautiful Ferraris ever without question, particularly the M model. OK, it has some issues but with those looks it can be forgiven. I dread to think what you regard as THE most hated Ferrari... probably a 400 like mine!

 

You did not mention it works some of the time. And if it does, it again points to another issue than the panel. A short in electronics does not come and go unless some loose metal bits or electrolyte found their way in. Yes there are exceptions with some coils and capacitors if damaged, but that is very rare. A shorted and/or half-seized pump drawing from the same circuit is then far more likely. So again, I am suspecting that circulation pump rather than the panel.
What do you get for risking someone else's $2600 panel? Imho the possible scenarios do not favor the approach. The test is not without risk, reason why new electronic bits cannot be returned, for damage can be done in an instant and invisibly. Even if you make right on any damage that may occur, your risk and time investment is higher than it should be for the possible return of information.

Like I said, have a look at what this panel controls and what other items are on that fuse. You need documentation and/or someone experienced with systemical diagnosis of electronics.

Corrosion... I have never seen corrosion on in-car electrics unless a lot of moisture can get to it.

 

Likely solution here..http://www.ferrarichat.com/forum/technical-q-sponsored-algar-ferrari/384339-550-blowing-fuse-ac-everytime-one-put-3.html

 

dave PM me if ur still trying to sort this - can give u access to my car if u need

 

Hated? Ouch!

You will find nothing but love here: Mondial - FerrariChat.com

And I would never say on this board what my Wife thinks about the 456.
Alden

 

I had a similar problem with my 95 456GT, it was the compressor unit. Turn the A/C, blow the fuse. I replaced it with a unit made by Sanden, when I asked the independent what was the difference he said about $2,000 and the Ferrari name on the unit. Sanden was the OEM for Ferrari, at the time.

Good luck,

MB

 

We at the Mondial corral are a passionate bunch as you can see! I think Dave has no animosity toward the Mondial as evidenced by his own ownership.



Dave is accurate as well, the Mondial would be on the short list as the most 'hated' Ferrari. Now if this is deserved or not belongs in a whole different thread.

Be well my friends!

Cheers