Remove the heater vent escutcheon
from the center of the dash.
Remove the front half of the heater
You should now be able
to access the brackets that hold the gauges in. The easiest way is to use
a "stubby" type philips head screwdriver. The screws are located
directly beneath each gauge. The top of the band that supports the rear of
the gauge simply slips into a slot above the gauge. One screw releases the
gauge back to clear the dash opening and pull it down so that you can
access the rear of the gauge with a small flathead screwdriver. Leave the
gauge connected so that it is reading the system voltage.
the flathead screwdriver to adjust the gauge to match both the battery
voltage and the idling voltage of your Z car's charging system. The
adjustment will have to be done to suit your own "eye" as the
gauge doesn't have enough markings to be real accurate anyway.