About 99.99% of the time this is caused by solder connections on the
cluster's printed circuit board (PCB). The PCB has traces on each side
of the board, and they are connected by 'revits'. Over time, heat and
vibration, these revits loosen up and the master signal, or common
ground goes away.

IF you can solder, the fix is to remove the cluster, and solder flow
the top and bottom sides of the PCB's revits. Clean the tach drive
module connections with a pipe cleaner soaked in TV Tuner cleaner, or
contact spray cleaner.

If you can't solder, or don't want to tackle this yourself, you can
still save some money by pulling the cluster yourself, and taking the
entire cluster to a speedo repair shop. Now, they will solder the PCB,
and test all guages. They will want to charge you for calibration, but
I would decline to save the money. Some shops will charge a flat fee of
$120 to do a repair and test, others will just do a solder reflow and
test for less money. This is what most independant shops do to make
this repair.

I have repaired many K car tachs using the above technique.

Good Luck,

Bill

The cluster is easy to remove on this model. The garnish panel under
the steering column needs to be removed, and then the column lowered to
facilitate removing the cluster. There are two nuts that you loosen to
lower the column. If I remember correctly, there are only two
connectors for the cluster, after the screws are removed.

If you have the column mounted gear selector, the indicator cable
should be disconnected before lowering the column too far. Otherwise,
it will get stretched and the gear indicator will be mis-aligned.

I believe that the air bag can be disabled by disconnecting the battery
for five minutes before starting work.

-KM