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Page 3
TG97A
Section A: Description and Operation (cont)
TABLE 2: A2-387 Regulator LED Indications
LED COLOR
ALTERNATOR / REGULATOR STATUS
REQUIRED ACTION
GREEN
(Solid)
Alternator and regulator operating normally.
No action required.
GREEN
(Flashing)
Surge suppression circuit disabled; alternator
still charging battery.
No action required.
AMBER
(Solid)
Voltage is below 25.0 V
If voltage is at or below regulator setpoint,
allow charging system to operate for several
minutes to normalize operating temperature.
If charge voltage does not increase within 10
minutes, go to Chart 1 on page 5.
AMBER
(Flashing)
No rotation detected.
Power down and restart alternator. If LED
remains flashing amber, perform trouble
-
shooting procedures on page 5.
RED
(Solid)
Field coil out of specification.
Power down and restart alternator. If LED
remains solid red, perform troubleshooting
procedures on page 5.
RED
(Flashing)
OVCO condition detected.
Power down and restart alternator. If LED
remains flashing red, refer to OVCO trou
-
bleshooting procedure on page 4.
A2-387 Voltage Regulator
Description and Operation
The CEN A2-387 voltage regulator can be mounted
directly on a C850 alternator. It may be used with or with-
out a J1939/temperature sense harness. The A2-387
regulator features include:
•
Overvoltage circuit cutoff (OVCO) that disables regula-
tor when voltage above 32 volts is detected for more
than 3 seconds.
•
Temperature/voltage compensation that senses ambi-
ent temperature within the battery box and adjusts out-
put voltage as necessary to maintain voltage set point
when used with temp/voltage sensing harness.
•
Battery voltage compensation when used with compat-
ible voltage sensing harness is connected to battery
bank. Regulator will boost voltage up to 1 volt to com-
pensate for voltage drop across cabling to batteries.
•
Overvoltage cutout (OVCO). Regulator will trip OVCO
when system voltage rises above 32 V for longer than 3
seconds. OVCO feature detects high voltage and reacts
by disconnecting field and turning off alternator. Re
-
starting engine or waiting until system voltage drops
below 28 V will reset OVCO circuit.
•
P (phase) terminal that can provide optional AC voltage
tap. P terminal signal frequency (Hz) x 10 = alternator
shaft rpm.
•
D+ terminal that can provide DC voltage signal to ve-
hicle electrical system, confirming alternator operation.
Figure 4: A2-387 Voltage Regulator
NOTE:
LED off = No power/output.
Alternator-to-regulator
harness connector
J1939 harness
connector
P terminal
IGN terminal
D+ terminal
Voltage selection
switch
