The RetroGauge™ Mini-Tach is designed for use with a standard ignition coil as factory fitted to 1967 and 1968 Ford Mustangs. For aftermarket ignition systems please read the important application note at the bottom of the page.
INSTALLATION:
1. Disconnect the battery negative terminal from the vehicle to completely isolate the electrical system.
2. Remove the instrument cluster according the to the workshop manual (several internet resources are also available to cover this procedure)
3. Unplug the instrument wiring harness from the main wiring loom and the wiper switch wiring harness from the rear of the cluster.
4. Unscrew the speedometer cable nut and carefully withdraw the cable from the speedometer shaft.
5. Lay the cluster face down on a fiat surface using a towel or similar to prevent any scratches to the instrument bezel
6. Using a Phillips (cross head) screwdriver remove the three screws retaining the plastic blanking plate or clock assembly. If the cluster is fitted with a clock the solitary wiring socket must be unplugged (blue with black stripe) and securely taped back into the harness. This should NOT be used for powering the Mini-Tach.
7. Remove the Mini-Tach from the die-cut packaging and carefully fit it into the cluster ensuring the two tabs locate in the housing fiange. The Mini-Tach should now sit fiush with the cluster and the three screw holes should align.
8. Re-fit the three Phillips head screws and hand tighten.
NOTE: While the cluster is out we recommend checking and replacing all dash cluster bulbs and/or blue lighting filters. Both items can be sourced from your favorite Mustang parts vendor.

WIRING:
1. Use minimum 18AWG (0.85mm2) automotive wiring for the connection. If possible use two different colors for the feed and the signal inputs. Ensure the feed and signal wires are not reversed. Damage to the electronics will occur as a result and warranty will be voided.
2. Run a wire for the Mini-Tach feed from a switched power source – preferably the ignition switch. Ensure the wire is protected with a suitable fuse (3 amp recommended). This will be connected to the +12VDC input terminal.
3. Run a wire for the Mini-Tach signal from the NEGATIVE side of the coil. This will be connected to the SIGNAL input terminal. Ensure the signal wire is NOT connected to the positive side of the coil (as was the case with the original factory tachometer).
4. The Mini-Tach has an internal grounding wire and will earth from the metal instrument cluster. If you do not have a good ground a separate wire can be run directly from the battery negative and connected to the tab terminal marked GROUND on the threaded stud of the Mini-Tach.
5. Re-install the cluster and connect the new feed and signal wires (and ground if necessary) to the Mini-Tach.
6. Reconnect the battery negative terminal.
7. Now start your engine and watch your new Mini-Tach fire up!

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