Directed Electronics ProSecurity RK20 Installation Manual page 14

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.
Important! Do not test tachometer wires using a test light or logic probe. The
vehicle will be damaged.
1. How to find a tachometer wire with your multimeter:
2. Set to ACV or AC voltage (12V or 20V is fine).
3. Attach the (-) probe of the meter to chassis ground.
4. Start and run the vehicle.
5. Probe the wire you suspect of being the tachometer wire with the red probe
of the meter.
6. If this is the correct wire the meter will read between 1V and 6V.
.
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