C.E. Niehoff & Co. N1245/N1248-3 Troubleshooting Guides - Manual (Page 6)

Page 6 TG44D
Section C: Advanced Troubleshooting
(CONT’D)
Troubleshooting
Shut down vehicle and restart engine. If alternator
functions normally after restart, a “no output condition”
was normal response of voltage regulator to “high volt-
age” condition. Inspect condition of electrical system,
including loose battery cables, both positive and
negative. If battery disconnects from system, it could
cause “high voltage” condition in electrical system,
causing OVCO circuit to trip.
If you have reset alternator once, and electrical system
returns to normal charge voltage condition, there may
have been a one time, high voltage spike, causing OVCO
circuit to trip.
If OVCO circuit repeats cutout a second time in short
succession and shuts off alternator relay circuit, try
third restart. If OVCO circuit repeats cutout, go to Chart
3, page 8.
N3044 and N3261 Regulators
DESCRIPTION AND OPERATION
N3044 and N3261 regulators are mounted directly to
the outside of the alternator.
Main diagnostic feature of
N3261 regulator consists of a
tricolored (green, amber, red) LED located on the top of
the regulator. The LED works like a voltmeter, measur-
ing charging voltage. See Table 2 for diagnostic features
and LED explanations.
N3044 and N3261 regulators have OVCO (overvoltage
cutout) and 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 F+ alternator circuit to open. This turns off alterna-
tor (LED on N3261 is solid RED). OVCO circuit is reset
when engine is restarted. Regulator then regains control
of alternator output voltage.
LED COLOR STATUS
TABLE 2 – N3261 Regulator Diagnostics
Alternator and regulator operating normally. GREEN Flashing
System voltage is lower than setpoint—electrical
load exceeds alternator rating at present rotor
speed.
ACTION
No action required.
AMBER Flashing
System voltage higher than setpoint.
If flashing more than 3 seconds, OVCO will trip,
disabling charging system. LED will flash RED.
Overvoltage condition. System diagnosis
required. Go to Chart 3, page 8.
RED Flashing
CLEAR LED off Check for system voltage at IGN terminal on regu-
lator. If OK, replace regulator. If not OK, check
vehicle wiring and ignition circuit. Energize circuit fault.
When loads decrease or speed increases, LED
should be flashing GREEN. If not, check drive
belt and charging system connections.
Solid OVCO tripped.