Re: [St] Speedometer woes

[Steve Boudreaux <steveboudreaux@xxxxxxxxx>]

I have a suggestion- mostly spectulative, but perhaps it will spark more informed responses and get you on the right track.  
 
If your ST has a OBD-II diagonstic port under the seat (like mine) ride to a Auto Zone, etc. and ask to use their code reader.  The diagonistic system may have stored a code due to the inop. speedo.  They will not know how to interpet the set code, but write it down and call the service dept. of a Triumph dealership- they should be able to tell you what that code(s) mean.
 
Most automotive electronics systems such as this one operate on a 5-volt supply.  
 
With the key in the on position, probe the connections from the speedo unit with a volt meter.  (Use an electronic one, that is protected by a fuse.  Lay in a store of replacement fuses of the right type- you can expect to blow a few.)  If this is the right path, you should see a voltage on the meter when you spin the wheel, which would INDICATE (again, this is speculative, and thus may not be conclusive) that the sending unit is working.  If you see no voltage or the multimeter fuse pops, try again with the meter set to amperage, then wattage.  
 
If that does not work, with the key off probe the sending unit with the multi meter set to ohms.  Note any change in resistance with wheel not moving and spun.
 
If the sender passes all or some of these test, check resistance on the speedometer leads.  
 
Disclaimer: THESE SUGGESTIONS ARE HIGLY SPECTULATIVE.  I am basing them on my knowledge and experience with auto electronics in general, NOT on any knowlege or experience with Triumph systems- but as late-model Triumphs have a OBD-II diagnostic port, I suspect they have electronic systems of similar design to automotive electronic systems I have some knowledge of.

Steve Boudreaux


--- On Sun, 8/31/08, st-request@xxxxxxxxxxxxxxxxxxxx <st-request@xxxxxxxxxxxxxxxxxxxx> wrote:

From: st-request@xxxxxxxxxxxxxxxxxxxx <st-request@xxxxxxxxxxxxxxxxxxxx>
Subject: St Digest, Vol 41, Issue 26
To: st@xxxxxxxxxxxxxxxxxxxx
Date: Sunday, August 31, 2008, 5:06 PM

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Today's Topics:

   1. Speedometer woes (LANCE G LACERTE, LANCE G LA CERTE)


----------------------------------------------------------------------

Message: 1
Date: Sun, 31 Aug 2008 14:32:25 -0600
From: "LANCE G LACERTE, LANCE G LA CERTE" <lacpsyd6@xxxxxxx>
Subject: [St] Speedometer woes
To: <st@xxxxxxxxxxxxxxxxxxxx>
Message-ID: <BAY112-DAV91A8635268FBF95966007835D0@xxxxxxx>
Content-Type: text/plain;	charset="iso-8859-1"

Hi All,

Originally joined this list back in '99 (?) with my, then new '99 ST. 
I 
still have it and need some help.

My speedo has suddently stopped working.  Had the bike in for a valve job 
and asked them to source the problem.  I was told that it was the 
speedometer itself and not the sender unit on the front wheel.  Without 
going into a long story about some poor service at the mechanic, I am 
somewhat dubious about their answer.  Is there a way for me to be able to 
check if it is the speedometer itself or the sender?   I don't have the 
means to plug it into the computer that they have at the mechanic.

If it does turn out to be the speedometer, does anyone have any leads for a 
used one.  A new one, on-line is (gasp!) $370.00.

Any help would be appreciated

Lance La Certe,    '99 Sprint ST 



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