Tachometer Output

The tachometer output on the TEC3r is a +12 Volt
square wave. Each time a coil fires, a ?tach pulse? is
generated. Therefore, the output from the tachometer signal
is ground, then +12 Volts for 30 degrees of crankshaft
rotation starting at each TDC/spark event. A 4-cylinder will
output 2 tach pulses per revolution, a 6-cylinder will output 3
tach pulses per revolution, an 8-cylinder will output 4 tach
pulses per revolution, and a 12-cylinder will output 6 tach
pulses per revolution. For applications that have a tachometer configured for a different number
of cylinders than the engine (i.e. a 6-cylinder car that was converted to an 8-cylinder), there is the
option of changing the tach output type in the software.
This type of signal is compatible with most new-style tachometers. However, some older
tachometers trigger off the high-voltage signal from the ignition coil (C-). These types of coils
require the use of a tachometer amplifier, since they are designed to trigger off of a 120 Volt
signal. Tachometer amplifiers (PN: 150-15210) are available from Electromotive to suit these
applications.