456 GTA Owners need some help please - Suspension ECU check P/N | FerrariChat

456 GTA Owners need some help please - Suspension ECU check P/N

Discussion in '456/550/575' started by spiderscott, Jan 17, 2020.

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  1. spiderscott

    spiderscott Formula 3
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    #1 spiderscott, Jan 17, 2020
    Last edited: Jan 17, 2020
    Another Suspension issue thread but with a difference.

    My 456 GTA (1997) has a suspension light on (common). i'm troubleshooting it at the moment for a video and spent all day on it, but just discovered something very strange and ideally need to confirm before heading down the wrong route with this.

    My Suspension ECU in the car is P/N 154835
    When I look this up the description is:

    'Ferrari 456 GT/GTA SHOCK ABSORBER CONTROL UNIT' - Not for 456 GTA

    This is confusing but when checking 171497 seems to be the correct suspension ECU for a GTA

    Can anyone physically confirm this thats owns a GTA ?, Also does anyone have a clue what the difference between both would be ? The suspension system and setup is identical between a GT and GTA ....or so I thought.

    My light is on the dash and all 4 corners have a 100% working actuator (taken for my 355 for testing) suspension small gears (top of shock) are all intact with no teeth missing and freely move.
    Upon startup NONE of my actuator internal mech rotate ?

    The strangest thing, when I purchased is the car this light has always been on. However I was able to get it to go out for a while with a combo of testing my actuators and reseating you suspension mode dash switch. That said the ride didn't feel like it ever changed out of Hard Damper (safety) mode when I changed the suspension mode settings.

    Any ideas ??
     
  2. spiderscott

    spiderscott Formula 3
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  3. tazandjan

    tazandjan Three Time F1 World Champ
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    #3 tazandjan, Jan 17, 2020
    Last edited: Jan 17, 2020
    Scott- The part is listed by Eurospares as 456 GT/GTA suspension control ECU, but then later says not for GTA. What it likely means is not as a replacement part for the GTA because at some assembly number (not in the parts catalog), they replaced 154835 with 171497. So if you need a replacement, get the later one. Ferrari does this fairly often and if you look at the replacement valve guides for the 456 or 456M, you will see they only list the sintered steel guides never actually fitted at the factory. The bronze guides that came with all 456s and 456Ms are not listed and not recommended as replacements.

    So you should be fine and your GTA was manufactured before they updated to the other ECU. Compared to the 575M, which had about a dozen or so shock absorber ECUs, some designated RHD or LHD for some unknown reason, this one is pretty simple.
     
  4. Rifledriver

    Rifledriver Three Time F1 World Champ

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    #4 Rifledriver, Jan 17, 2020
    Last edited: Jan 17, 2020
    The real live parts catalog is for GT and GTA. It shows 154835 for the GT and 171497 for GTA.

    Eurospares did a poor job with their website. The Ferrari printed and online sources show no such conflict.

    Ferrari parts catalogs are not perfect but typically far better than other sources besides Ricambi America. I don't know how anyone ever gets the correct parts from most.
     
  5. spiderscott

    spiderscott Formula 3
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    Two guys I was hoping would chime in here ...cheers.

    So whats the consensus ? Do you think mine is the wrong one in there. I was semi hoping Terry was right because I'm otherwise scratching my head trying to figure what else this could be (bad switch, steering sensor etc) but on the other hand hoping it's not the wrong eco as 171497 is hard to come by.

    Brian, other than the usual actuators, suspension cog broken/spline issues have you seen any other causes on the system such as a bad Suspension ECU ?

    I can't figure out why with known good actuators installed and held off the shocks I cannot get any motion from them start up. they should go through there check movement routine.
     
  6. Rifledriver

    Rifledriver Three Time F1 World Champ

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    I don't guess, cannot afford to. I have equipment that makes diagnosis easy. If the ecus were interchangeable Ferrari would not have gone to the expense of having different ones.

    I trust you checked the fuse.
     
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  7. tazandjan

    tazandjan Three Time F1 World Champ
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    Brian- How many failed shock absorber ECUs do you see?
     
  8. Qavion

    Qavion F1 World Champ
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    #8 Qavion, Jan 18, 2020
    Last edited: Jan 18, 2020
    Regarding fuses...

    The Bilstein ECU has a couple of different power sources.
    Battery power from the "fuseholder".
    Battery power through relay panel fuse 20 via relay "S" (which is active with the ignition key in RUN). This fuse also powers the Power Steering ECU.

    I noticed in your battery drain video that you didn't show the 16 fuse "fuseholder". I'm not sure where it is on a GTA. As mentioned in the other message thread, it looks something like this:

    Image Unavailable, Please Login

    Here's my latest wiring diagram for the suspension system:

    Ferrari_456_ABS_&_ASR_Wiring_Diagram
     
  9. Rifledriver

    Rifledriver Three Time F1 World Champ

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    I think once years ago in a 355.
     
  10. tazandjan

    tazandjan Three Time F1 World Champ
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    Brian- That was my point. I would bet that the shock ECU he has was fitted at the factory before the GTA version was available. Odds of it having failed and then being replaced with the wrong ECU are pretty slim.
     
  11. Rifledriver

    Rifledriver Three Time F1 World Champ

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    Well the book I got the part number from was printed before his car was built.

    Perfectly good parts get replaced all the time. How else do you think repair bills get so high?
     
  12. Rifledriver

    Rifledriver Three Time F1 World Champ

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    Terry. Replacing Motronic boxes is rare too but I have a 550 here with 2 bad ones. They broke as an act of human intervention I believe using some unsound methods to diagnose a problem. Most electronic components are replaced for 2 reasons 1. Bad diagnosis. Throwing parts at a problem until it goes away. 2 The old act of human intervention. Someone broke it.

    I said earlier, I don't guess at problems despite the fact it is the most commonly used form of diagnosis.

    Like I said, how do you think some of these repair bills get so high?
     
  13. tazandjan

    tazandjan Three Time F1 World Champ
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    Brian- Sounds good to me.
     
  14. Qavion

    Qavion F1 World Champ
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    I probably should have said "non-M GTA". I'm starting to think the early cars didn't have this fuseholder module. In this case, my wiring diagrams are probably useless for half of the 456 community :( I didn't understand the evolution of the 456.

    Do the early cars have a vertical relay panel and the later ones a horizontal one like the 550?
     
  15. spiderscott

    spiderscott Formula 3
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    Hi Ian

    Thanks very much for the wiring diagram, it is helpful even though its for the M, there are some common areas.

    I did some extensive searching around the car and combined with the parts diagram on the early 456 I can conform there was no extra fuse board as per the M models, they made some quite significant wiring changes between both models.
     
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