2.2 Connecting the Tachometer
The latest tachos have a small M8 connector and the back surface and are supplied with a
moulded mating connector with flying leads. These are connected as follows:
Connect this to a good chassis ground
Connect to a fused 12 volt supply from master switch
(preferred) or ignition switch
Negative side of coil or to dedicated tacho output from
engine ECU
Shift Light 1 or Tell-Tale
Enable
Supplied shift light ONLY positive or 52 mm gauge tell-tale
enable.
Supplied shift light positive ONLY
Connect to one side of push button
Connect to other side of push button
Older tachometers are supplied with flying leads so that you can fit the connector of your choice to
the car loom. The table lists the functions of the five free wires.
A fused 12 volt supply from the master switch or Ignition if
there is no master switch
Negative side of coil or to dedicated tacho output from
engine ECU
Supplied shift light ONLY or 52 mm gauge tell-tale enable
Supplied shift light ONLY
Black/White and Red Wires
Connect the black wire to a good earth point and the red to a suitable switched and fused 12 volt
supply. A fuse of 1 amp is sufficient. The tacho requires a few seconds to power up so
connecting it to the master switch is preferable to the ignition supply.
On powering up, the tacho drives both hands forwards and then backwards into stops. After this
the tell-tale hand moves to the maximum rpm recorded since it was last reset.
Violet/Brown Wire
The trigger input can be connected to the switched end (-) of the coil directly or through the
supplied Filter Box for older tachos but if there is a dedicated tacho pulse from the ignition system
this would be better. If you are using a modern engine management system, you may need a 3.3
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