The Tach Cluster
by Erich Bozzer
How many times have you seen a Tach Instrument Cluster at a
swap meet and thought that it would be nice to replace your base instrument cluster? You
look further and find out that in order to perform this change you also need the unique
wire harness that goes with it. Then you learn that the wire harness is either missing or
too expensive. Anyway do you really want to tear your whole dash out to replace the
wiring? Good news, now you can modify your existing base wiring to be used with the Tach
As you know, when the Tach was put into the right center pod
of the cluster it forced the temperature and fuel gauges to move to the two outer pods.
Ford replaced the charge and oil pressure gauges with warning lights. All these changes
can be summed up into 4 categories: 1) Pin-out changes in the connector on the back of the
cluster. 2) Oil pressure indication, 3) Charge indication and 4) The tach connection.
Let's start with the charge indication. The amp gauge is
basically a worthless instrument. How many times has it actually told you that your
charging system was bad? The warning light is not much better because by design it can
only tell you when the voltage regulator is not working. It does not indicate complete
charging system performance. Also, to switch over to the warning light is a major rework
of the dash wire harness as well as replacement of the short alternator harness. This
information leads me to suggest that the charge indicator in the cluster can be deleted.
An add on voltage gauge put in a hidden place is not only the easiest thing to do, it is
also the best charge system indicator. So, what we will do is: not use the amp gauge wires
at the back of the cluster, add an aftermarket voltage gauge (if desired) and leave the
rest of the charge system untouched. If you're interested in all the details to wire in
the warning light, write to us at the Registry if there is enough response, a future
article may be done.
Now to the fun part. Just follow the step by step procedure
in proper order to install your new in-dash tachometer. Please read it through first so
you get the big picture before you start.