550 Steering ECU

Carl, I'm guessing that little ECU controls a proportional spool valve in the hydraulics which, at high current, is open further, and allows the P/S pump to provide more assist, and at low current, is closing and providing less assist. Seems to be a range of 600ma on the top and effectively 100ma or even 0 on the bottom, depending on how much assist you want at 200 MPH. I'd bet Ferrari spent a lot of field time testing & tuning that curve. I'm surprised they put it in the WSM.

I've used similar electrohydraulic control systems in the past to control large conveyers feeding threshing/grinding machines. Moog and others make these for industry, and they can be a real bear to tune.

Probably the easiest way to start tuning this system would be to intercept the speed signal before it gets to the Servotronic ECU and reoutput it to the ECU with a different characteristic curve, just to get a feel for what happens. It would take a Frequency to Frequency converter to do this, so I'll do some research and see what's available.

Others may have better ideas.

 

FBB, where do you get the USD1,000 figure? As I posted on your other thread, last month, I got a new FHP steering ECU for significantly less than that from Maranello:

http://ferrarichat.com/forum/showpost.php?p=140879134&postcount=5

 

deetee

Which part number are you referring to?
FBB is correct for the 550/575 as most Ferrari parts vendors price the p/n 175891 FHP steering ECU between $900 and $1k.
Bill
FL

 

Bill, the link I posted In #3 above answers your Qs. And my point is that regardless of what most parts dealers charge, Maranello's price is significantly lower, as I pointed out to FBB a month ago. I just checked their HP, still priced at GBP313.

BTW, are you from the Big Island? I'm from Oahu.

 

Sorry deetee, did read your link and somehow managed to miss the part number. Don't quite understand the price discrepancy. Unfortunately paid over $900 here in the states for one as didn't see any options. I'll drop you a pm as I'd like to understand more about the "Maranello price".

Bill
FL

 

Bill,

"Maranello" refers to Maranello Concessionaires, the UK parts dealer. I don't know if it's OK to post commercial web addys on FChat so will instead reply further via PM.

Takashi

 

Would someone who owns one of these FHP ECU's be kind enough to post the ZF Servotronic P/N, if it's visible? I think it should be 7038 900 288, but I'd like to have confirmation of that.

I've just purchased a used steering ECU which was represented to be Ferrari P/N 175891 (the FHP P/N), however the ZF Servotronic P/N marked on it (7038 900 250) is identical to the non-FHP ECU in my 550.

The Ferrari P/N has been conveniently obliterated on the part that I purchased, and someone has handwritten "175891" on it. Let's just say I have doubts that ZF would use the same P/N for both ECU's.

First pic is the ECU I just bought. Second pic is the ECU presently in my 550.

TIA
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looks like u got ripped off........

 

I think you got porked. Here is a pic of my FHP ECU
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You should be able to tell an immediate difference in steering wheel tightness at almost idle speeds. Plug and play. If no difference then it's not the advertised part

 

Thanks guys, especially 00 550 for the pic. That's pretty conclusive!

Hopefully this will have a happy ending - I bought this part, along with a number of others from a well known supplier in the UK. If they take them back for full credit, I'll give them the kudos they deserve. If they don't, then I'll make sure this forum and a couple of others know who they are & what they did.

 

From the WSM I conclude that all this unit does is convert a frequency (roadspeed) to a current in a non-linear fashion. I guess the only difference between the FHP and the standard unit is the non-linearity of the curve. I don't think there can be a big internal difference between the two and I am pretty sure it should be possible to modify a standard one to work like a FHP one.
It is very obvious that unit is not originally FHP but John could still be lucky and have a modified unit instead of a faked one.

John, is the unit sealed or can it easily be opened? I would like to compare the innards of FHP vs. standard.

 

I am sure there will be... I volunteer to look into it, I once studied electrical engineering so I am quite familiar with the smell of solder

If anyone can help with an FHP version of the graph and maybe pictures of the innards of these units that'd be a great starting point. Even if the units are completely sealed there are plenty of solutions for building this type of circuitry from scratch, it's not terribly complicated and I am sure it should be possible to build one in professional quality for a hundred something dollars in component cost when not counting the hours of development and design of course; for replicating the functionality I will require the characteristic graph and also a unit to do some measurements and testing on.
I am not sure what unit is fitted to the 456 but I am sure I can take that out of my car and have a peek myself one of these days. I'm beginning to become fascinated.

 

Jeez, like I needed an excuse to take it apart . This isn't the FHP ECU, nor even the non-FHP Ferrari one. It's another mistake I picked up awhile back off eBay, and it has Audi's Olympic logo on it, otherwise it looks exactly like the Ferrari ECU's.

Piece of cake to open up with a pair of small screwdrivers. Unfortunately I'm now at the outer limits of my expertise, so I'll leave it to the electronic components and circuits gurus to figure out from here:

(Edit: BTW, my bogus FHP ECU does not look as though it's been opened - I'm sure it's possible to open it without scratching the plastic a bit as I did with this Audi ECU, but it would be tough, and I see no signs of forcible entry at all on it )
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John, thanks, that does help. It looks as if the solution here has been to use a digital rather than an analog way to build the required circuitry of frequency to current conversion. I guess that could be so there can be diagnostics coupled to it, that the behavior in case of a malfunction of the frequency input or similar remains predictable, and of course that you can have an endless variety of units with just the program as a differentiator.

The 93C46 on that board is a programmable EEPROM; so it is likely that a non-FHP can be flashed with FHP once a copy of the data is obtained. Easily done if you have access to an EEPROM programmer (easy) and a FHP unit (less easy). This is assuming a FHP and non-FHP is identical apart from the programming, but that's very likely since they are the same generation.

EDIT: another solution is to engineer an analog version of the unit doing the same as an FHP from a known graph. Benefit of such an own engineering could be that it will be possible to attach a regulator to it for adjustment to personal liking, or to obtain adjustment by a switch to flick between two or more options. Some blanks would need to be filled in such as the frequency used to work the steering rack valve; that transistor is for sure not dissipating much heat in that configuration so it must be a switched control.

 

If it is simply a EEPROM, either Eric355 or gobble should be able to download the contents of an FHP EEPROM to hard drive, erase a non-FHP EEPROM and copy the contents from the hard drive. That is what they are doing now when they clone alarm fobs.

Unless, of course, there is some sort of proprietary code to make it work. Worth a try. Greg Calo has the gear, too.

 

It looks like all we need is a donor FHP relay.

Maybe if we got enough of us together we could buy one from Maranello Concessionaires, the UK parts dealer. They're about half price there.

 

Here's the scenario.

We buy a FHP relay, John picks it up while coming through London on his monthly vacation trip. He sends his bogus relay and the new relay to Eric who re-flashes the bogus relay, when he gets it back he puts it in his car and tests it. Then he sends his original relay to Eric for re-flashing, when that comes back he sends the bogus (now re-flashed) relay to the next guy in line and that person simply repeats the operation until every one in the group has a re-flashed relay.

We end up with everyone having a re-flashed relay plus the one we bought and John has a spare. Then we sell the new relay to recover our costs and we're home free.

Now we sell the service to late comers and start looking for a retirement villa in the South of France to buy with our proceeds

Sounds good to me

 

Then we do the same thing with the 550 FHP shock ECU

 

If you want one picked up from Maranello's I live about 20 minutes away from them.

 

Dave- Copying a EEPROM does not harm it. Anybody's EEPROM could be copied and then replaced in the car with no damage. If someone wanted to buy one for his car, it could be copied and anybody else who wanted oned could just chip in towards the person who bought it. Should not cost more than $100 to reprogram the EEPROM in the standard ECU, including shipping.

Assuming there is nothing weird about the EEPROM programming.