F.2. Tachometer Output
The tachometer output on the
TECgt
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 p
revolution, an 8-cylinder will output 4 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.
er
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.
Figure F.2.1:
Typical tachometer wiring.
F.3. The Fuel Pump Relay Output
The fuel pump output is designed to provide activation of the fuel pump relay on a vehicle. It is
NOT designed to power the fuel pump directly. See
Figure F.3.1
for wiring instructions.
The software allows the user to define the amount of time that the fuel pump primes the system
when the
TECgt
is first turned on. This ensures adequate fuel rail pressure on start-up.
When the
TECgt
is first turned on, the fuel pump will run for the amount of time defined in the
software. If the engine is not cranked during or after this time, the fuel pump will turn off. Once the
engine is cranked, the fuel pump will turn back on. Essentially, the fuel pump should always be running
when the engine is rotating.
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TECgt Manual Version 2.0
- Page 82 -
©2008 Electromotive, Inc.
