C.E. Niehoff & Co. C703/C703A & C706 Troubleshooting Guides - Manual (Page 5)

Page 5 TG31K
Section C: On-Vehicle Troubleshooting
A2-214 Regulator Troubleshooting
A2-214 regulator is either attached directly to the
outside of alternator or remote-mounted on the vehicle.
Main diagnostic feature is a green lens LED located on
the front of the regulator. LED indicates whether regula-
tor has been energized. See Table 3 for LED indication
and status.
Regulators with OVCO (overvoltage cutout) will trip at
vehicle electrical system voltages above 32 volts that
exist longer than 3 seconds. OVCO feature detects high
voltage and reacts by signaling the alternator field
circuit to open. This turns off alternator. Restarting
engine resets OVCO circuit. Regulator regains control
of alternator output voltage.
REMOTE-MOUNTED REGULATORS:
CHECK CONDITION OF FUSE IN WIRING HARNESS BEFORE TROUBLESHOOTING
TABLE 3 — A2-214 Regulator
LED Indications and Status
INDICATION STATUS
ON steady Normal regulator operation.
Alternator is producing output.
FLASHING Regulator is receiving energize
signal. LED will fl ash until
alternator produces output.
OFF Regulator is not receiving energize
signal or OVCO has tripped.
A2-325 Regulator Troubleshooting
A2-325 regulator is attached directly to the outside of alternator or mounted remotely on the vehicle.
Main diagnostic feature is a tricolored LED next to the harness receptacle on regulator. LED works like a voltmeter,
measuring charging voltage. See Table 4 for diagnostic features and LED explanations.
Regulators with OVCO (overvoltage cutout) will trip at vehicle electrical system voltage above 32 volts that exists longer
than 3 seconds. OVCO feature detects high voltage and reacts by signaling relay in alternator field circuit to open. This
turns off alternator (LED is flashing RED—some units may flash AMBER). OVCO circuit is reset when engine is restarted.
Regulator regains control of alternator output voltage.
LED COLOR STATUS
TABLE 4 — A2-325 Regulator Diagnostics with Engine On
Alternator and regulator operating normally. GREEN Solid
Low system voltage — Electrical load exceeds alterna-
tor rating at present rotor speed.
ACTION
No action required.
When loads decrease or speed increases, LED
should be solid GREEN. If not, check drive belt
and charging system connections.
AMBER Solid
High system voltage – May occur during normal load
switching.
If flashing more than 3 seconds, OVCO will trip,
disabling charging system. LED will flash RED.
Overvoltage condition. Attempt reset. System
diagnosis required. See OVCO condition in
“General Troubleshooting” section on page 6.
RED Solid
(Some models) Alternator fault — No output.
(Some models) OVCO tripped. Flashing
Flashing OVCO tripped.
Replace alternator.
Overvoltage condition. Attempt reset.
System diagnosis required. Go to page 7.
No power to ignition or regulator is defective. OFF Go to Chart on page 7.