308 Speedo, Odo, Sender System Fix | Page 4 | FerrariChat

308 Speedo, Odo, Sender System Fix

Discussion in 'Technical Q&A' started by RJay, Apr 8, 2006.

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  1. DustyM

    DustyM Karting

    Jun 7, 2011
    124
    Ireland
    Full Name:
    Jon Miller
    Hi,

    I came upon this thread whilst googling for problems with a 308 speedo and wonder if anyone can help.

    I have a 1976 308 which has an intermittent speedo fault (both the speedo and Odo will stop working) and this has become more regular and now almost never works.

    During a recent service the garage swapped the sender unit for a different one but it made no difference so the original was put back. They said it must be the speedo unit, so I removed this and sent it away for overhaul, unfortunately this has also made no difference.

    So today I tried some trouble shooting. Just with a regular Multimeter

    I checked the sender unit wiring and have +12 on the green with ignition on but only 0.5v on the red wire.

    I jacked the car up and with it running in 5th gear also checked the voltage on the red wire - still a constant 0.5v. No pulsing

    I unplugged the speedo and then the voltage on the red wire at the sensor jumps to 12v constant, reconnect the speedo and it drops back to 0.5v constant

    I'm at a loss as to what to try next.

    Can anyone help please? My electrical knowledge is OK at a basic level.

    Cheers
     
  2. Will2012

    Will2012 Rookie

    Sep 5, 2012
    2
    Brazil
    Full Name:
    William Felipe Medei
    Hello guys !

    I really need a say 115y, someone would have to sell me?

    I'm trying to adapt a uaf 2115 but without success.

    William grateful, Brazil
     
  3. gerritv

    gerritv Formula 3

    Jun 18, 2001
    1,400
    St Catharines
    Full Name:
    Gerrit
    PM returned.

    UAF2115 is a nicer chip and easier to find but difficult to use as a replacement without making a whole new PCB.

    Gerrit
    ex 11966
     
  4. Will2012

    Will2012 Rookie

    Sep 5, 2012
    2
    Brazil
    Full Name:
    William Felipe Medei
    I found say the 115h, and replaces, however the speedometer still does not work.

    It is powered by 12v and signal speed in hz does not leave the ic

    Any tips?
     
  5. Nickt

    Nickt Formula 3

    Feb 24, 2006
    1,741
    Iver, Buckinghamshir
    Full Name:
    Nick T
    Hi Guys
    I just found this thread, and its awesome... Hopefully someone can help or point me in the right direction
    my 1978 308GT4 seems to eat speedos, its been through at least 4 of them, the fist when it was only a few months old.
    The latest speedo I fitted a few years back (bought off ebay) was fine, but then the trup meter stopped working. The speedo and the odo were fine. The trip meter would wind back to 0000 and stay put.

    The last time I used the car the odo stopped working too.

    Is this something that is easy to fix? The case is very fragile, it looks like the previous owner has had a go at it as the case is araldited back together around the bezel. I haven't looked inside yet as I am not sure if there is anything fixable in there.... unless you tell me dufferent
     
  6. Nickt

    Nickt Formula 3

    Feb 24, 2006
    1,741
    Iver, Buckinghamshir
    Full Name:
    Nick T
    #81 Nickt, Jul 8, 2013
    Last edited by a moderator: Sep 7, 2017
    Hi Guys
    Has anyone done the fix to the 308 speedo as in the derawing below?

    Can you tell me what the right hand diode is please? I can make out 91f but that does not seem to come up with any component.

    the other parts are:
    2n4401, 1n914 and a 12k resistor.

    I believe this circuit stops the IC from being spiked.
    Image Unavailable, Please Login
     
  7. RJay

    RJay Formula Junior

    Jun 26, 2004
    261
    Colorado
    Full Name:
    Bob
    Nick,

    The diode is a 1N914. I meant to write 914 (looks kinda like 91f) just like the other. These are fairly generic diodes and can be substituted easily. Sorry for the confusion. Also, I don't check this site very often so, again my apologies for taking so long.

    Best Regards,

    Rjay
     
  8. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    I bought a used speedometer for my 308 to experiment with led illumination ... and no longer need it. Contact me if you need one for parts and wish to help me recover my costs.
     
  9. waymar

    waymar Formula 3

    Sep 2, 2008
    1,321
    Northeast, PA - USA
    Full Name:
    Wayne Martin
    What face plate is it? Any photos?
     
  10. Radiogeek1

    Radiogeek1 Rookie

    Jul 2, 2008
    31
    Pleasant Ridge, MI
    Full Name:
    Bret Scott
    Here's the sign of a good post. Over 14 years old, and still providing helpful information! :)

    I own a 1983 400i, and it appears that the circuit design is different than the one shown above, employing an SAA1004N frequency divider chip in addition to the SAY115Y chip. Although it is fully functional, it is registering about 11% high , and having read this post, I have hope I can perform an adjustment to bring it closer to correct speed.

    Thanks to RJay and others that have contributed over the years!

    Bret

    '83 400i Automatic
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