Intermittent Speedometer and Odometer | FerrariChat

Intermittent Speedometer and Odometer

Discussion in 'Boxers/TR/M' started by marchambault, Aug 13, 2011.

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  1. marchambault

    marchambault Rookie

    Aug 4, 2011
    20
    Toronto, Canada
    #1 marchambault, Aug 13, 2011
    Last edited: Aug 13, 2011
    Hi again,

    I have an intermittent speedometer and odometer problem again with a 1993 512 TR. The speedometer is accurate and doesn't read incorrectly. It does not go up and down erratically. The problem it has is that it will either function for 10 min, 5 or 2 min and then suddenly stop and go back down to zero and the odometer stops working as well. Then, it starts back up again and works fine for another 2, 1, or 10 min and stops again.

    Again, it is both the odometer and speedometer that stop working at the same time.

    Could it be a speed sensor problem on the engine or the actual speedometer connections in the back of the dash?

    Let me know if you have heard about or have gone through this problem before. I want to avoid removing the dash and instrument assembly if at all possible.

    Thanks,
     
  2. Philwozza

    Philwozza Formula 3

    Apr 23, 2009
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    Phil Worrall
    #2 Philwozza, Aug 13, 2011
    My guess is either the sensor on the engine or the wiring from the sensor into the cockpit.

    The wire from the sensor is common to both instruments on the Testarossa. It comes from the sensor then splits at the back of the central instruments and then feeds the speedo. As you have a problem with both instruments the problem must be the system from the engine to cockpit.
    Check the black and white connections on the bell housing first as these connectors are in the rough and open environment of the engine bay.

    HTH

    P
     
  3. Philwozza

    Philwozza Formula 3

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    Phil Worrall
    #3 Philwozza, Aug 13, 2011
    Last edited by a moderator: Sep 7, 2017
  4. Testarossa Lover

    Testarossa Lover F1 Rookie
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    Dec 31, 2006
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    Haig Barsamian
    #4 Testarossa Lover, Aug 13, 2011
    I am having problem as well, I had the speedo fixed twice. Both time it only lasted 200 miles or so. First rpair resulted in Speedo stuck at 80 miles in ignition on. the second repair just died. I need some help as well. The sending unit was replaced.
     
  5. Spasso

    Spasso F1 World Champ

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    #5 Spasso, Aug 13, 2011
    Last edited: Aug 13, 2011
    The speedometer and odometer on my TR are connected to a pulse generator located on the FORWARD end of the transmission, at the front of the engine more or less, just inboard of the airpump. (1988.5 model, VIN 76639)

    Mine was erratic until I rebuilt the terminals inside the connectors.
     
  6. jselevan

    jselevan Formula 3

    Nov 2, 2003
    1,873
    #6 jselevan, Aug 13, 2011
    Rather common failure mode in Boxer. I suspect the Testarossa series uses the same sender unit. I experienced precisely the same symptoms. Changed the sender at the transmission and problem is now history. Expensive sender (as I recall approximately $150 U.S.), but easier and less costly than a problem with the speedo.

    Jim S.
     
  7. janrbh17

    janrbh17 Rookie

    May 6, 2012
    26
    Norway
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    Jan R B Hansen
    #7 janrbh17, May 27, 2012
    marchambault;

    have you solved your intermittent speedo-problem? I have a 93- TR with exactly the same problem. If you have the solution i would be glad if you shared it with me...:)

    BR JR Hansen, Norway. [email protected]
     
  8. tf308

    tf308 Formula 3

    Dec 14, 2003
    1,168
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    Tim
    #8 tf308, May 28, 2012
    I think it is a problem on the speed sensor on the engine/transmission. That unit sends the signal making both the odometer and speedo work. No signal will kill both.


    My speedo stopped working but the odometer kept working. I sent the speedo head to Alta speedometer in California and they confirmed my problem was in the speedo head. $280 and it was fixed. (look for a recent post with sadly little replies from the gallery)

    if its not melvok or a few others...not many are working on their own cars.
     
  9. marchambault

    marchambault Rookie

    Aug 4, 2011
    20
    Toronto, Canada
    #9 marchambault, May 30, 2012
    No haven't solved it yet. The RPM gage works fine, and really that's all I need. If you know your RPM vs. speed correlations, you are good to go. I will fix the problem next year with the major that is scheduled.
     
  10. brettski

    brettski Formula 3

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    #10 brettski, May 30, 2012
    Monsieur Archambault,

    you still have the Testarossa book i lent you...which will necessite another visit...which will mean that i have grab a few more bottles of wine...or maybe it's cheaper to just find another book...

    but it will be more fun this way !

    b
     
  11. 512BLU

    512BLU Karting

    Nov 5, 2003
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    #11 512BLU, May 31, 2012
    I also own a 1993 512TR and had the same problem a few years ago. It was the transducer on the transmission. Very easy and non expensive part to replace. Curious, What is the VIN on your 93 512TR? Mine is 95076.
     
  12. mjh366

    mjh366 Karting

    Jul 26, 2007
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    #12 mjh366, May 31, 2012
    Same thing happened to my 88 T/R. Very easy fix, speedometer sensor at the front of the engine near the oil filter. I should have cleaned the connectors first, might have saved a few $.
     
  13. Tifoso1

    Tifoso1 F1 Rookie

    Nov 18, 2003
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    #13 Tifoso1, Jul 16, 2012
    Just came back from a short drive in the Testarossa and I noticed both the speedometer and the odometer have stopped working with all of the other gauges functioning as they should. It would appear from this thread and others here in the archive that it is most likely the sender/sensor unit that needs to be replaced. Does anyone have a photo or picture of the actual sensor unit and its location ?

    Thanks in advance.
     
  14. 302Tim

    302Tim Formula 3

    Jul 2, 2011
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    #14 302Tim, Jul 16, 2012
    Last edited by a moderator: Sep 7, 2017
    Mine has a small leak that I need to address so I haven't had it out but here is the sensor. Not sure how much fluid is lost when you pull it...
    Image Unavailable, Please Login
     
  15. Melvok

    Melvok F1 World Champ
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    #15 Melvok, Jul 17, 2012
    Last edited: Jul 17, 2012
    Correct Jim, good photo !

    I have replaced my speedometer sensor at the front of the engine near the oil filter once ... no more problems since that time.
     
  16. MannyGMT2

    MannyGMT2 Formula Junior

    Feb 27, 2006
    429
    Montreal, Canada
    #16 MannyGMT2, Jul 27, 2012
    I have the same issue on my 94 512TR. The speedometer stopped working for a about 20 seconds (the tachometer is always ok) . So I should check the speedometer sensor as shown in the previous post/pic?
     
  17. Melvok

    Melvok F1 World Champ
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    #17 Melvok, Jul 27, 2012
    Yes .... disconnect and see what happens ... connect (maybe dirty contact ?) again ...

    And these sensors are not realy exepensive ...
     
  18. marchambault

    marchambault Rookie

    Aug 4, 2011
    20
    Toronto, Canada
    #18 marchambault, Jul 30, 2012
    Monsieur Grand Tourisme,

    You are correct. In a moment of Scatter Brain it was brought back in the 512TR to my place. It shall indeed require another visit, but it will have to wait until I come back from vacation.

    I'll bring the wine, but I'll be prepared to drive the 400 and or the 456 for real this time!
     
  19. marchambault

    marchambault Rookie

    Aug 4, 2011
    20
    Toronto, Canada
    #19 marchambault, Aug 13, 2012
    Mine is 94778 :) send me some pics if you can.
     
  20. marchambault

    marchambault Rookie

    Aug 4, 2011
    20
    Toronto, Canada
    #20 marchambault, Aug 13, 2012
    Hey Melvok. Your pics are great. A quick question: is it possible to replace the sensor without a lift? Maybe I can actually repair this myself. How easy is it to access the sensor to check the connections?
     
  21. Melvok

    Melvok F1 World Champ
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    #21 Melvok, Aug 14, 2012
    Yes, piece-of-cake Marc !

    No problem (in my 512TR at least ;:)
     

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