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Accessory wire
An accessory wire shows +12V when the key is in the accessory and run positions.
It does not show +12V during the cranking cycle. There are often more than one ac-
cessory wire in the ignition harness. The correct accessory wire powers the vehicle's
climate control system. Some vehicles may have separate wires for the blower motor
and the air conditioning compressor. In such cases, it is necessary to add relay to
power the second accessory wire.
Tachometer wire
Note: The system has Virtual Tach which automatically test the engine volt-
age in automatic transmission vehicles. The below wire test would be
used only if Virtual Tach or Voltage Mode is not working. When install-
ing this unit on a manual transmission vehicle, the wire must be used.
To test for a tachometer wire, a multi meter capable of testing AC voltage must
be used. The tachometer wire will show between 1V and 6V AC. In multi-coil
ignition systems, the system can learn individual coil wires. Individual coil wires
in a multi-coil ignition system will register lower amounts of AC voltage. Also, if
necessary, the system can use a fuel injector control wire for engine speed sens-
ing. Common locations for a tachometer wire are the ignition coil itself, the back
of the gauges, engine computers, and automatic transmission computers.
WARNING! Do not test tachometer wires using a test light or logic probe (com-
puter safe test light). This will damage the vehicle.
How to find a tachometer wire with your multi meter:
1.
Set to ACV or AC voltage (12V or 20V is fine).
2.
Attach the (-) probe of the meter to chassis ground.
3.
Start and run the vehicle.
4.
Probe the wire you suspect of being the tachometer wire with the red probe
of the meter.
The wire should read between 1v and 6v and will normally change when
revving up the engine. If the voltage changes with engine speed, you have
the correct wire.
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