Speedo died. Which sensor is it? | FerrariChat

Speedo died. Which sensor is it?

Discussion in '348/355' started by WATSON, May 26, 2019.

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  1. WATSON

    WATSON Two Time F1 World Champ
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    Sep 9, 2010
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    My speedo died today. All kinds of fun things happened after that.

    1. My F1 car will not shift past 2nd gear
    2. The gearbox warning light is on. (start off, but turns on once the car starts moving and no speed is sensed)
    3. The suspension light is now on

    I don't think it is the speedo itself, but it could be.

    Which sensor kills the speedo?

    This one:
    https://www.ricambiamerica.com/162916-sensor-speed.html

    Or this one:
    https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/355-group/f355-m5-2-1996/gearbox-covers-and-lubrication/149095-sensor-speedo.html
     
  2. Enzojr

    Enzojr F1 World Champ

    Dec 12, 2013
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    Tomy
    ?????
    No clue, but that’s an odd list of things to appear at the same time.
    Having a MT everything with paddles just baffles me ;)
    Hopefully one of those (cheap) sensors will fix all that.
     
  3. phrogs

    phrogs F1 Veteran
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    Apr 13, 2004
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    The second one, mine did this as well.

    Get up to speed in 2nd then hit neutral, then the downshift paddle, it should go to 6th gear. You should be able to down shift as you wish from there to limp home.
     
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  4. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
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    Mitchell Le
    THis one

    149095 SENSOR/SPEEDO
     
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  5. Qavion

    Qavion F1 World Champ
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    Not odd. The speedo feeds all those systems. Was the Check Engine light on, too?

    Replacement tutorial here:

    https://www.dropbox.com/sh/kufk5c92mfqd50n/AABQnT5MSW3R2UiMRKvZkoNfa/Ferrari DIY/F355 Speed Sensor Replacement.pdf?dl=0

    If you want to do a Stooge repair on the "Type 2" sensor:

    http://www.dinoplex.org/instruments/vegliaspeedosensor/

    Instructions on how to check Hall-type sensors are also included in the above.... recommended before you buy a new one, as it could still be a faulty speedo. The speedometer processes the signal from the sensor and then sends it on to the other systems.
     
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  6. Qavion

    Qavion F1 World Champ
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    Wiring diagram here:

    Instrument Wiring Diagram (5.2)

    There are a few connectors between the speedo sensor and the speedo that you could check:

    The connector on the sensor itself
    The 12 pin connector behind the left hand rear shock. "41019"
    The white connector forward of the centre console "41024"
    The connector on the back of the speedo.

    There is a power fuse, but you would have a lot more instruments failing if that was blown.
     
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  7. Subarubrat

    Subarubrat Formula 3

    Apr 1, 2009
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  8. WATSON

    WATSON Two Time F1 World Champ
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    Excellent help. Where is the above connector located? I had the dash pod out to fix some leather issues....did I miss something??
     
  9. Qavion

    Qavion F1 World Champ
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    #9 Qavion, May 26, 2019
    Last edited: May 26, 2019
  10. Qavion

    Qavion F1 World Champ
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    Note that sensor replacement can be done without removing the wheel and inner guards if you're lucky. If not, you may need to remove the wheel, guards and fabricate a special socket.

    If you know 100% that the sensor is broken before removal, you can always cut off the electrical plug and use a standard socket.
     
  11. WATSON

    WATSON Two Time F1 World Champ
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    I cleaned up the back of the speedo connector and the wire harness connection. But that did not fix the issue...and now the suspension light. Hummm
    If the speedo itself crapped out, would that matter to the TCU? It does get the speed input from the sensor not the speedo. Right?

    Now that I look at my repair records, I replaced that gearbox speedo sensor about 8 yeas ago. Not that big of an effort. I even have the socket with the notch in it. :)
    Can it crap out that fast???

    I know... I shall pour a glass of brunello and think about this....
     
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  12. Qavion

    Qavion F1 World Champ
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    No, the speedo processes the signal from the sensor (dividing the frequency in two), then sends it to all the other systems via splices on a white wire (with yellow stripe). See diagram link above.

    I'll have to have a look at the Workshop Manual to remind myself what the TCU does with the signal.
     
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  13. WATSON

    WATSON Two Time F1 World Champ
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    Hummm that complicates things doesn't it?
     
  14. Qavion

    Qavion F1 World Champ
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    Well, it could mean that your speedo is broken. That's why I suggested testing your speed sensor first. If you know someone with an oscilloscope, you may be able to tap into the signal without removing it, but this may be impractical to do this because the car has to be moving to test the sensor properly (with the oscilloscope plugged in somewhere). Probably the easier way would be to remove the sensor and check it (as per the Veglia/Borletti tutorial).

    The sensors are prone to damage because of heat in that area. Yours may have failed again.
     
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  15. Wade

    Wade Three Time F1 World Champ
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    Doesn't look familiar at all since the ad states for the 348 as well.

    However, another ad with an almost identical item calls it the "360 Spider Shock Absorber Suspension Module"

    https://www.ebay.com/itm/2004-Ferrari-360-Spider-Shock-Absorber-Suspension-Module-Box-Computer-VDO/323111983135


    Image Unavailable, Please Login
     
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  16. WATSON

    WATSON Two Time F1 World Champ
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    Huh... Thanks for that.

    I know these cars pretty well and do not recall seeing that box anywhere. BUT....I don't know it all so thought I would ask.
     
  17. Qavion

    Qavion F1 World Champ
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  18. johnk...

    johnk... F1 World Champ
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    Ferrari part 198308 is the shock ECU for a 360 Challenge Stradale.
     
  19. WATSON

    WATSON Two Time F1 World Champ
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    Which fuse is this? I might as well check it while i wait for the new sensor to arrive.
     
  20. Qavion

    Qavion F1 World Champ
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    The AC System fuse, but then all your instruments would not be working (apart from the clock). The suspension light would not illuminate if this fuse was blown.

    Also, the suspension light would not illuminate if this fuse was blown (and possibly the gearbox light)
     
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  21. WATSON

    WATSON Two Time F1 World Champ
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    New sensor.....no joy.
     
  22. Qavion

    Qavion F1 World Champ
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    #23 Qavion, May 31, 2019
    Last edited: May 31, 2019
    Ugh.... I've seen the price of new mph speedos. About 2~3 times the price of kph speedos.

    Did you test the old sensor?

    Also, it might be worth doing a few wiring checks. e.g. The fuse will be ok, but do you have 12 volts at the speedo plug on the sensor's green/white wire with the ignition on? You can also check for volts on pin 2 of the 12 pin plug near the top of the left hand (rear) shock strut.

    There has been a case of the reluctor in the gearbox coming adrift on F348's

    https://www.ferrarichat.com/forum/threads/348-mystery-part-on-transmission-magnetic-plug.576834/#post-146022289


    On the bright side, at least you don't have a F348-style mousetrack seatbelt system which can blow up the speedo.
     
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  23. WATSON

    WATSON Two Time F1 World Champ
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    Thinking it is a wiring issue.... I messed around with the two connector blocks you mentioned (mainly the back one) and then tried again.

    Now, the suspension light is off....? But the speedo does not work. Gah!

    I have to go study your wiring diagrams and see if I can check the voltage at the speedo as you suggest.

    Thank you for the help.
     
  24. WATSON

    WATSON Two Time F1 World Champ
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    You found a new MPH speedo??? I can't even find a decent used one.
     

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