AMP EFI MS3Pro - Honda Alternators; Other Alternators; Barometric Correction

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7.1 Basic / Load Sections 7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL

The easiest way to control this alternator is to wire a digital frequency input pin to the L terminal. If you wish to

add load monitoring, connect the “F” terminal to another digital frequency input pin.

Settings:

• Control mode: Open loop duty

• Control output: any unused digital frequency input pin

• Output polarity: Normal

• Frequency: 128 Hz

• Load monitor input: any unused digital frequency input pin (optional)

• Capture polarity (if using load monitor input: Inverted

7.1.8.6 Honda alternators Most 1990s era and later Honda alternators used an on/off system that could switch

between a charging voltage and a low output mode that produces around 12.5 to 12.7 volts to keep battery voltage

from dropping. Grounding the “C” terminal on the alternator will put the alternator into low output mode. The

MS3Pro supports this with on/off control, which allows the ECU to shut down the alternator during cranking and

for a few seconds afterward. This can help with smoother startup. Simply wire the alternator “C” terminal to an

unused high current or PWM output, allowing the MS3Pro to ground this pin and switch the alternator to low output

mode.

Settings:

• Control mode: On/Off

• Control output: Use any available high current or PWM output.

• Output polarity: Inverted

7.1.8.7 Other alternators Many alternators do not have or need computer control. Internally regulated alterna-

tors, if not of the “one wire” type, typically only need an “exciter” signal (switched 12 volts) or a warning light signal

to turn on. If the alternator uses an external voltage regulator connected to a ﬁeld terminal, you can either use the

regulator included with the alternator, or use the Chrysler directions.

If you encounter a computer controlled alternator not contacted here, consult a dealer service manual for more

information.

7.1.9 Barometric correction

This screen works similar to the warmup enrichment display, showing a percentage correction curve as a function

of barometric pressure.

AMP EFI MS3Pro manual version 1.202, ﬁrmware 1.5.0, 4/21/2017 Page 138