New speedo sending, still dead....? | FerrariChat
Buy

New speedo sending, still dead....?

Discussion in 'Technical Q&A' started by ducowti, Apr 11, 2008.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. ducowti

    ducowti Formula 3

    Jan 27, 2008
    1,557
    NY/SC
    Full Name:
    David
    #1 ducowti, Apr 11, 2008
    My 86 328 speedo has been intermittently working last two weeks. Checked the connection at the unit, it was snug and clean inside. Dis- and reconnected all the blocky connections under the dash to no effect. Today I installed a new unit from Ricambi (even expedited it) and NOTHING :confused:

    Any ideas? Other connections or anything else to check? How do I get the gauges out so I can check behind the speedometer? I know some of you have experienced a 'cold' situation where it works after the car is warm but I wouldn't expect that with a new unit - I only tested this in my 'hood so it's not like I was driving for 20'.

    Thx. This will really suck if I just blew $240 for a paperweight.
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,931
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #2 Steve Magnusson, Apr 11, 2008
  3. ducowti

    ducowti Formula 3

    Jan 27, 2008
    1,557
    NY/SC
    Full Name:
    David
    #3 ducowti, Apr 11, 2008
    Thanks for that. I did search and while I'm sure my search method could be improved, this site's search engine could also use some improvement :/ I foolishly accepted the board's consensus 'it's the sending unit always happens etc etc' w.out eliminating other putative causes. Not to say I'm not grateful for all the replies but hey, murphy gets you when he can right? I'm driving to DC tomorrow and was racing today's deadline to get the issue resolved so I could drive 600mi back and forth and not worry about no speedo (and the odo) so I was hasty and not thorough. Ah well....you'll be seeing me trying to hock this on the 3X8 forum :D
     
  4. Darolls

    Darolls F1 Veteran
    BANNED

    Jul 2, 2003
    7,782
    Full Name:
    Sparky
    #4 Darolls, Apr 11, 2008
    In 99.9% of speedo problems, the impulse generator is the demon. Check all wiring and if no problem, you'll probably have to send the speedo out for repair.
     
  5. Testa

    Testa Karting

    Mar 28, 2004
    50
    #5 Testa, Apr 12, 2008
    It's not unlikely that the sender unit is bad again. I had this problem some years ago with the TR (same sender unit as 328 if i remember correct). Speedo was not working - sender unit replaced - worked for 100km then the same problem again. Had a strong discussion with the dealer because he was telling me that now it can only be the speedo itself but not the sender unit. Replaced the sender unit again and since this time speedo is working well.
     
  6. ducowti

    ducowti Formula 3

    Jan 27, 2008
    1,557
    NY/SC
    Full Name:
    David
    #6 ducowti, Apr 12, 2008
    Doubtful in this case since the new unit didn't work from foot one after replacing. Certainly possible the new unit was bad too but since it didn't do the trick I put the old back in and guess what - it worked after a few hundred feet and worked for 6mi test drive. We'll see if it comes up now as I depart....we shall see....
     
  7. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,931
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #7 Steve Magnusson, Apr 21, 2008
    Last edited by a moderator: Sep 7, 2017
    (Responding to a PM)

    Dave -- Here is more detail on the two tests for the 116987 Speedometer Sensor. Since you don't have a way to elevate the chassis to rotate the rear wheels, just make the wires long enough so that you can carry the multimeter inside the passenger cabin with you while making the Test 2 measurement. Good luck, and please report the results for Test 2 if you get that far (unfortunately, on a TR the 116987 Speedometer Sensor isn't so easily accessed so I can't/won't make a measurement for comparison).
    Image Unavailable, Please Login
    Image Unavailable, Please Login
     
  8. ducowti

    ducowti Formula 3

    Jan 27, 2008
    1,557
    NY/SC
    Full Name:
    David
    #8 ducowti, Apr 22, 2008
    Last edited by a moderator: Sep 7, 2017
    Steve, this is super, thank you for taking the time to do this!
    Image Unavailable, Please Login
     
  9. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    18,054
    USA
    #9 f355spider, Apr 22, 2008
    No kidding, Steve you are the MAN! :)
     
  10. ducowti

    ducowti Formula 3

    Jan 27, 2008
    1,557
    NY/SC
    Full Name:
    David
    #10 ducowti, Apr 22, 2008
    Test 1:
    +12V+

    Test 2:
    +12V+ w.only ignition on, same as Test 1 (but also while in motion). Driving the car had no apparent effect - i.e. I got ~13V before I even moved; then, the voltage fluctuated ~+13V regardless of speed. Am I doing something wrong? I have followed your instructions - will post pics of my fugazzi setup in a few minutes...
     
  11. ducowti

    ducowti Formula 3

    Jan 27, 2008
    1,557
    NY/SC
    Full Name:
    David
    #11 ducowti, Apr 22, 2008
    Last edited by a moderator: Sep 7, 2017
  12. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,931
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #12 Steve Magnusson, Apr 22, 2008
    Did you also try measuring using the AC volts scale? The volts AC should increase with speed as the pulses come faster and faster; however, if the pulses are very, very narrow, you may not be able to detect with a multimeter and might need to get an oscilloscope-type meter to look deeper -- and we really need someone with a working system to confirm what a "good" Test 2 result is like using this method :( At least you know Test 1 is OK ;)
     
  13. ducowti

    ducowti Formula 3

    Jan 27, 2008
    1,557
    NY/SC
    Full Name:
    David
    #13 ducowti, Apr 22, 2008
    Did not; I'm not enough of an electrical head to think outside only what I know. Maybe I'll give it a shot tomorrow. Thanks for checkin in to this thread Steve.
     
  14. Bavarian Motorist

    Bavarian Motorist Formula Junior

    Apr 10, 2007
    943
    Westchester/NYC
    Full Name:
    Mike
    #14 Bavarian Motorist, Apr 22, 2008
    Off topic, but, nice interior :p
     
  15. ducowti

    ducowti Formula 3

    Jan 27, 2008
    1,557
    NY/SC
    Full Name:
    David
    #15 ducowti, Apr 22, 2008
    It's got a few minor weary spots but it's in overall very good shape!
     

Share This Page