Speedo Bounce FIx
pjrose at frontiernet.net
Mon Nov 13 14:25:04 EST 2006
At 9:25 AM -0500 11/13/06, W.G. Giles wrote:
>My speedo bounces sometimes what is the fix. Is it in the cluster or
Most commonly it's the IC. I fixed mine about a year ago --after
doing two things. First-- was to run an extra ground wire as shown in
the following link.
That repair wire jumpers over a crack that commonly occurs in the
upper PC board's circuit--a crack which prevents the "other side"
(left side in the photo) of the board from having a good ground. That
crack tends to occur near the base of a small two-pin connector (you
can see the underside of this connector in the second photo--two
small holes and associated solder points). Merely installing this
repair wire as shown serves to cure a common problem with the IC,
whereby there is very dim IC backlighting along with simultaneous
display of both green turn-signal arrows (also erroneous indiication
of high-beam headlights). But this "fix" alone was *not* enough to
cure my bouncing speedo.
It happens that a crack (or cold solder joint) can also occur at the
base of the little (green plastic) 2-pin connector, and this can be
the cause of the bouncing speedo needle. A bad solder joint at the
base of this 2-pin connector makes the connector unable to
adequately ground its mating pins (these pins carry ground to the
speedo circuit board below). Using an 8x magnifier, I was able to see
a faint crack right at the soldered metal base of the 2-pin
connector. I heated this spot carefully with my low-wattage soldering
iron and my bouncing speedo was fixed. At least for the time being
(one year so far).
I've added a photo that shows the two small "speedo ground pins"
which are located near the top edge of the IC (--arrow-- at bottom of
photo); here they're shown emerging from the white, intermediate
circuit board cover. When the uppermost circuit board is put in
place, these pins must slide into the 2-pin connector discussed
This all probably sounds about as clear as mud. Will be easier to
understand once you have the IC removed and begin disassembly. Use
only a low-wattage iron.
Phil Rose Rochester, NY USA
'91 200q (156K, Lago blue)
mailto:pjrose at frontiernet.net
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