7.1 Basic / Load Sections 7 ADDITIONAL ITEMS: BEYOND BASIC FUEL AND IGNITION CONTROL
era Chrysler alternators with the MS3Pro - or if you happen to be low on available pins, you can run a computer
controlled Chrysler alternator with a 1970s era electronic voltage regulator.
Chrysler alternators have two different wiring types. The “single field” design first appeared in 1960 and ran
through 1969, then resurfaced around 2007. The “dual field” design first appeared in small quantities in 1969,
became standard in 1970, and started to be phased out after 2006. In spite of the name, both types have only
one set of field windings; the difference is whether the alternator has one or two field terminals. The “single field”
design brings out the 12 volt supply pin to the field windings, with the other end of the field winding grounded to
the housing. The “dual field” alternators bring out both ends of the field wiring.
The field coil current draw can be 5 amps or more depending on the alternator. Consequently, we recommend
using a solid state relay to drive the field coil. The solid state relay needs to be powered from switched 12 volts,
and connects to the 12 volt field terminal. The other field terminal, if available, should be grounded to the alternator
housing.
All Chrysler alternators use the same settings.
• Control mode: High speed field feedback control
• Control output: Use any available high current or PWM output.
• Output polarity: Normal
7.1.8.3 Miata alternators 1999 and later Mazda alternators used an ECU controlled field coil. However, instead
of directly running the field coil, the ECU supplies 5 volts to a switching transistor inside the alternator to regulate
the output voltage. You can control this alternator with the output from a high current or PWM output with a pull up
resistor, or repurpose an unused spark output to provide a 0-5V signal without a pull up. Although they are marked
as inputs, the digital frequency “inputs” can also supply a suitable 0-5V signal.
The alternator connector has two pins. The “P” pin is the 0-5V signal for field control; the “D” pin is a fault
detection pin which the MS3Pro currently does not support.
Pull up method Settings:
• Control mode: High speed field feedback control
• Control output: Use any available high current or PWM output.
• Output polarity: Inverted
Spark output method
• Control mode: High speed field feedback control
• Control output: Use any available spark output or digital frequency input.
• Output polarity: Inverted for the spark outputs, normal for digital frequency input.
7.1.8.4 Chevrolet 4 wire alternators GM’s “CS” series alternators showed up in the late 1990s and were used
through the mid 2000s. These used a four pin connector; not all applications used all the pins. The MS3Pro cannot
fully control this alternator’s output voltage, but the alternator will support a delayed turn-on to reduce alternator
load on startup.
• P - Phase output. Used for engine speed output on diesel applications. Not used with MS3Pro.
• L - Lamp. While this connection is used for an alternator warning lamp, it also doubles as a turn-on signal.
When the alternator is supplied 12 volts through this pin - even if through a fairly high resistance - the
alternator will switch on.
• I/F - Ignition or field. This pin can have two functions depending on the exact application the alternator is
from - some alternators use this as an input and others use it as an output. The ignition terminal will trigger
the alternator if supplied with 12 volts. On other alternators, however, this pin is called the field pin and is an
output to indicate alternator load.
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 136
To Next Page
Loading...