C.E. Niehoff & Co.
N1601, N1602, N1603, and N1604
Alternator Troubleshooting Guide
Hazard Definitions
These terms are used to bring attention to presence of hazard(s)
of various risk levels or to important information concerning
product life.
Indicates presence of hazard(s) that
CAUTION
will or can cause minor personal
injury or property damage.
Indicates special instructions on
NOTICE
installation, operation or mainte nance that are important but not
related to personal injury hazards.
Table of Contents
Section A: Wiring Diagrams ............................... 2 – 3
Section B: Basic Troubleshooting ............................4
Section C: Advanced Troubleshooting .............. 5 – 10
Battery Conditions
Until temperatures of electrical
NOTICE
system components stabilize, these
conditions may be observed during
cold-start voltage tests.
• Maintenance/Low Maintenance Battery
— Immediately after engine starts, system volts are
lower than regulator setpoint, amps are medium.
— 3–5 minutes into charge cycle, system volts
increase, amps decrease.
— 5–10 minutes into charge cycle, system volts
increase to, or near, regulator setpoint and amps
decrease to a minimum.
— Low maintenance battery has same characteristics
with slightly longer recharge times.
• Maintenance-free Battery
— Immediately after engine starts, system volts are
lower than regulator setpoint, low charging amps.
— Once charge cycle begins, low volts and low amps
are still present.
— After alternator energizes, voltage will increase
several tenths. Amps will increase gradually, then
quickly, to medium to high amps.
— F i n a l l y , v o l t s w i l l i n c r e a s e t o s e t p o i n t a n d a m p s w i l l
decrease.
The time it takes to reach optimum voltage and amperage will vary with engine speed, load, and ambient
temperature.
• High-cycle Maintenance-free Battery
These batteries respond better than standard maintenance-free. Charge acceptance of these batteries may
display characteristics similar to maintenance batteries.
• AGM (Absorbed Glass Mat) Maintenance-free Batter y
These dry-cell batteries respond better than standard
maintenance-free. If battery state of charge drops to
75% or less, batteries should be recharged to 95% or
higher separately from the engine’s charging system to
avoid damaging charging system components and to
provide best overall performance. Charge acceptance of
these batteries may display
maintenance batteries.
characteristics similar to
Battery Charge Volt and Amp Values
Volt and amp levels fluctuate depending on the battery
state of charge. If batteries are in a state of discharge—as
after extended cranking time to start the engine—system
volts will measure lower than the regulator setpoint after
the engine is restarted and system amps will measure
higher. This is a normal condition for the charging system;
the greater the battery discharge level, the lower the system
volts and the higher the system amps. The volt and amp
readings will change as batteries recover and become fully
charged: system volts will increase to regulator setpoint
and system amps will decrease to low level (depending on
other loads).
• Low Amps: Minimum or lowest charging system amp
value required to maintain battery state of charge,
obtained when testing the charging system with a fully
charged battery and no other loads applied. This value
will vary with battery type.
• Medium Amps: System amps value which can cause
the battery temperature to rise above adequate charging temperature within 4-8 hours of charge time. To
prevent battery damage, the charge amps should be
reduced when battery temperature rises. Check battery
manufacturer’s recommendations for proper charge
amp rates.
• High Amps: System amps value which can cause
the battery temperature to rise above adequate charging temperature within 2-3 hours of charge time. To
prevent battery damage, the charge amps should be
reduced when battery temperature rises. Check battery
manufacturer’s recommendations for proper charge
amp rates.
• Battery Voltage: Steady-state voltage value as mea-
sured with battery in open circuit with no battery load.
This value relates to battery state of charge.
• Charge Voltage: Voltage value obtained when the
charging system is operating. This value will be higher
than battery voltage and must never exceed the regulator voltage setpoint.
• B+ Voltage: Voltage value obtained when measuring
voltage at battery positive terminal or alternator B+
terminal.
• Surface Charge: Higher than normal battery voltage
occurring when the battery is disconnected from
battery charger. The surface charge must be removed
to determine true battery voltage and state of charge.
• Significant Magnetism: Change in strength or intensi-
ty of a magnetic field present in alternator rotor shaft
when the field coil is energized. The magnetic field
strength when the field coil is energized should feel
stronger than when the field is not energized.
• Voltage Droop or Sag: Normal condition occurring
when the load demand on alternator is greater than
rated alternator output at given rotor shaft RPM.
TG29D
Page 1
Section A: Wiring Diagrams
CEN N1601, N1602, N1603, N1604
Alternator and Regulator Description
and Operation
The alternators listed below are self-rectifying. All windings and current-transmitting components are nonmoving, so there are no brushes or slip rings to wear
out. Energize switch activates regulator. Field coil is
then energized.
• N1601 28 V 400 A
• N1602 28 V 400 A with optional 28 V/ 14 V
(50 A maximum on 14 V)
• N1603 28 V 450 A
• N1604 28 V 400 A
N3107 regulator used on some N1601, N1603, and
N1604 alternators maintains alternator output voltage
at regulated setting as vehicle electrical loads are
switched on and off. Alternator output current is selflimiting and will not exceed rated capacity of alternator.
The regulator has:
• an AC terminal to provide optional AC voltage
output tap.
• overvoltage cutout (OVCO). 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 relay in field control circuit to
open. This turns off alternator. Restarting engine
resets OVCO circuit.
The following regulators receive energize signal after
engine is running:
• N3118—used on some N1602 alternators
• N3211—used on some N1601 and N1603 alternators
• N3223—used on some N1602 alternators
• N3236—used on some N1604 alternators
• N3237—used on some N1602 and N1603 alternators
• N3245—used on some N1602 and N1603 alternators
Regulator monitors alternator rotation and provides
field current only when it detects alternator shaft rotating at suitable speed. After regulator detects alternator
rotation, it gradually applies field current, preventing an
abrupt mechanical load on accessory drive system. The
soft start may take up to 10 seconds at full electrical
load. These regulators:
• are negative temperature compensated. Setpoints
are 28.0 ± 0.2 V (and on N3118 and N3223, 14.0 ±
0.2 V. See below.) at 75F. N3237 and N3245 regulators are negative temperature compensated according to switch-selected battery type. Customer selects
position per application.
• provide overvoltage cutout (OVCO). Regulator will
trip OVCO when system voltage rises above 32 V in
a 28 V system (16 V in a 14 V system) for longer than
3 seconds. OVCO feature detects high voltage and
signals the field circuit to open, turning off alternator. Restarting engine resets OVCO circuit.
• maintain alternator output voltage at regulated
settings as vehicle electrical loads are switched
on and off.
N3118 and N3223 regulators can be used in single
28 V or dual voltage applications. The regulators:
• allow single-voltage operation (28 V only). 14 V
single voltage application is not available with
these regulators.
• provide optional 28 V/14 V output only from the
regulator when phase cable from alternator is
connected to regulator.
Page 2
TG29D
B+ connections on alternator
Both positive terminals must be connected together at battery positive
potential, using interconnect cable and cable of suitable size as part
of vehicle cabling, when alternator is installed in vehicle and during
operation.
Interconnect
Positive cables
from vehicle
cable
IGN terminal
14V B+
terminal
(N3118 and
N3223 only)
AC terminal
Section A: Wiring Diagrams (CONT’ D)
Case ground: N1601, N1603
Isolated ground: N1604
Figure 3 — N1601-1 thru -4, N1603-1/-2, and N1604-1/-2
Wiring Diagram
B– connections on alternator
Both B – terminals must be connected to the vehicle’s common ground,
using interconnect cable and cable of suitable size as part of vehicle
cabling, when alternator is installed in vehicle and during operation.
Figure 1 — N1601, N1602, and N1603
Alternator and Regulator Terminals
B+ connections on alternator
Both positive terminals must be connected together at battery positive
potential, using interconnect cable and cable of suitable size as part
of vehicle cabling, when alternator is installed in vehicle and during
operation.
Positive cables
from vehicle
Interconnect
cable
IGN terminal
AC terminal
•••
N3223 only —
J1939 connector
Figure 4 — N1602-1, -2, -4, -5, - 6 Wiring Diagram
B– connections on alternator
Both B – terminals must be connected to the vehicle’s common ground,
using interconnect cable and cable of suitable size as part of vehicle
cabling, when alternator is installed in vehicle and during operation.
Figure 2 — N1604
Alternator and Regulator Terminals
TG29D
Figure 5 — N1602-3/-7 and N1603-3 Wiring Diagram
Page 3
Section B: Basic Troubleshooting
Tools and Equipment for Job
• Digital Multimeter (DMM)
• Ammeter (digital, inductive)
• Jumper wires
Identification Record
List the following for proper troubleshooting:
Alternator model number _________________________
Regulator model number ________________________
Setpoint listed on regulator ______________________
Preliminary Check-out
Check symptoms in Table 1 and correct if necessary.
TABLE 1 – System Conditions
SYMPTOM
Low Voltage Output
High Voltage Output
No 28 V Output
No 14 V Output
Check: loose drive belt; low battery
state of charge.
Check: current load on system is
greater than alternator can
produce.
Check: defective wiring or poor ground
path; low regulator setpoint.
Check: defective alternator or
regulator.
Check: wrong regulator.
Check: high regulator setpoint.
Check: defective regulator.
Check: alternator.
Check: broken drive belt.
Check: battery voltage at alternator
output terminal.
Check: defective alternator or regulator.
Go to Chart 2, page 7.
ACTION
Basic Troubleshooting
1. Inspect charging system components for damage
Check connections at B– cables, B+ cables, B+
interconnect cable, B– interconnect cable, and
alternator-to-regulator harness. Repair or replace
any damaged component before troubleshooting.
2. Inspect all vehicle battery connections
Connections must be clean and tight.
3. Determine battery voltage and state of charge
If batteries are discharged, recharge or replace
batteries as necessary. Electrical system cannot
be properly tested unless batteries are charged
95% or higher. In addition, open circuit voltages
must be within ± 0.2 V.
4. Connect meters to alternator
Connect red lead of DMM to alternator anti-drive
end B+ terminal and black lead to alternator
anti-drive end B– terminal. Clamp inductive
ammeter on anti-drive end B+ cable.
5. Operate vehicle
Observe charge voltage at batteries with engine
running (nom. 27-28 V or 13.5-14.0 V).
If charge voltage is above
32 V for 28 V system or
16 V for 14 V system,
immediately shut down
system. Electrical system
damage may occur if charging
system is allowed to operate
at excessive voltage. Go to
Table 1 at left.
If voltage is at or below regulator setpoint, let
6. Observe charge volts and amps
7. Batteries are considered fully charged if charge
8. If charging system is not performing properly,
• N1601, N1602, N1603—Chart 1 on page 6
• N1604—Chart 4 on page 9
CAUTION
charging system operate for several minutes to
normalize operating temperature.
Charge voltage should increase and charge amps
should decrease. If charge voltage does not in crease within ten minutes, continue to next step.
voltage is at regulator setpoint and charge amps
remain at lowest value for 10 minutes.
go to:
Page 4
TG29D
Section C: Advanced Troubleshooting
Advanced Troubleshooting
Shut down vehicle and restart engine. If alternator
functions normally after restart, a “no output condition”
was normal response of voltage regulator to overvoltage
condition. Inspect condition of electrical system, including loose battery cables, both positive and negative.
If battery disconnects from system, it could cause overvoltage 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, overvoltage spike that caused
OVCO circuit to trip.
N3223 only: If OVCO circuit repeats cutout a second
time in short succession and shuts off alternator field
circuit, try third restart. If OVCO circuit repeats cutout
a third time, check color of LED while engine is running
and go to Chart 3a or 3b, page 8.
Other regulators: If OVCO circuit repeats cutout a
second time in short succession and shuts off alternator
F– circuit, try third restart. If OVCO circuit repeats
cutout, go to Chart 3 on page 8; or for N1604, go to
chart 5 on page 10.
N3223 Regulator
DESCRIPTION AND OPERATION
N3223 regulator with OVCO is attached directly to
the outside of alternator. Regulator setpoint has flat
temperature compensation. Voltage setpoint is 28.0
±1.0 V and 14.0 ±0.5.
Main diagnostic feature of regulators consists of two
tricolored (red, amber, green) LEDs located on the
side of the regulator. One LED indicates 28 V system
performance, the other LED indicates 14 V system
performance. The two LEDs work independently of
each other. See Table 2 for diagnostic features and
LED explanations.
OVCO (overvoltage cutout) operation:
• 14 V side trips at voltage higher than regulator
setpoint that exists longer than 3 seconds of reading
voltage above 16 V. OVCO feature detects overvoltage
and reacts by disabling the alternator field circuit.
This turns off alternator (14 V LED is steady RED
light). OVCO circuit will reset automatically when:
— restarting engine
OR
— system voltage falls below 11 V.
• 28 V side trips at voltage higher than regulator
setpoint that exists longer than 3 seconds of reading
voltage above 32 V. OVCO feature detects overvoltage
and reacts by disabling the alternator field circuit.
This turns off alternator (28 V LED is steady RED
light). OVCO circuit will reset automatically when:
— restarting engine
OR
— system voltage falls below 22 V.
LED COLOR
FLASHING
Amber
Red
STEADY
Green
Amber
TG29D
TABLE 2 – N3223 Regulator LED Operation Modes
STATUS
No AC/rotation. See Chart 1 on page 6 for 28 V systems, Chart 2 on page 7 for 14 V systems.
Alternator is shut down and is not producing power for either voltage. 28 V side trips after 3 seconds of
reading voltage above 32 V. 14 V side trips after 3 seconds of reading voltage above 16 V. Regulator remains
in this mode until reset by restart ing engine or if system voltage drops below 22 V or 11 V, respectively.
See Chart 3a or 3b on page 8.
Respective system voltage is at regulated setting and operating under control.
Respective system voltage is below regulated setting. Alternator is not producing power or circuit is overloaded. See Chart 1 on page 6 for 28 V systems, Chart 2 on page 7 for 14 V systems.
Page 5
Section C: Advanced Troubleshooting (CONT’D)
Chart 1 – N3107, N3118, N3211, N3223, N3237, N3245 – No 28V Alternator Output – Test Charging Circuit
(N1604: start with Chart 4 on page 9)
STATIC TEST – KEY ON, ENGINE OFF
Shut down vehicle and restart engine. Does alternator function normally after restart?
Yes No
Regulator responded to overvoltage condition.
Go to Chart 3 on page 8 to troubleshoot OVCO.
Shut off engine. With key off, engine off: Test for battery voltage at alternator 28 V B+ terminal.
Does battery voltage exist?
Yes
No
Repair vehicle ignition circuit wiring as necessary. Continue test.
With key on, engine running: Test for battery voltage between IGN terminal on regulator and alternator B–
terminal. Does 28 V battery voltage exist?
Yes No
Repair vehicle ignition circuit wiring as necessary. Continue test.
With key off, engine off: Remove alternator-to-regulator 4-pin harness from regulator. Test for battery voltage
across sockets D and C in harness plug. Does 28 V battery voltage exist?
Yes No
Alternator is defective.
With DMM, check resistance across field coil. Connect red lead of DMM to socket A in alternator-to-regulator
harness plug. Connect black lead to B+ terminal on alternator. Does meter show 1.0 ± 0.2 ohms?
Yes No
Connect jumper wire from socket A in regulator harness plug to B – terminal
on alternator. Spark will occur. Touch steel tool to shaft to detect significant
magnetism. Is shaft magnetized?
Yes
No
Alternator is defective.
Test phase signal into regulator (AC). Set meter to diode tester:
Connect red lead of DMM to socket C of regulator harness and
black lead to socket B. Meter should show voltage drop value.
Then reverse meter lead connections. Meter should show OL
(blocking).
Yes
Regulator is defective.
Alternator is defective.
No
Page 6
SOCKET CONNECTIONS
A F–
B Phase Signal AC
C B–
D 28 V B+
Figure 5 – Alternator-to-Regulator
4-Socket Harness Plug
TG29D
Section C: Advanced Troubleshooting (CONT’D)
Chart 2 – N3118 and N3223 only – No 14 V Alternator Output – Test Charging Circuit
Shut off engine. With key off, engine off: Test for battery voltage of 14 V output terminal on regulator.
Does +14 V battery voltage exist?
Yes
Repair vehicle wiring as necessary.
Set DMM to diode tester. Connect red lead of DMM to socket C of regulator harness plug and black lead to each phase pin in phase harness plug.
Meter should show voltage drop value.
Then reverse meter lead connections. Meter should show OL (blocking).
Yes
Regulator is defective.
Alternator is defective.
No
SOCKET CONNECTIONS
A F–
B Phase Signal AC
C B–
D 28 V B+
No
TG29D
Figure 6 – Alternator-to-Regulator 4-Socket Harness Plug
PIN CONNECTIONS
A Phase P1
B Phase P2
C Phase P3
Figure 7 – Phase Connection 3-Pin Harness Plug
Page 7
Section C: Advanced Troubleshooting (CONT’D)
Chart 3 – N3107, N3118, N3211, N3223, N3237, N3245 – OVCO Trip – Determine 28 V or 14 V
With meter red lead on 28 V B+ at battery and black lead on chassis ground, start engine.
Watch meter dial: Does meter read charge voltage above 29 V?
Yes
28 V side tripped OVCO circuit.
Go to Chart 3b.
Chart 3a – N3118, N3223 – No 14 V Alternator Output – Test OVCO Circuit (14 V LED on N3223 steady RED)
Unplug alternator-to-regulator 4-socket harness from regulator. At receptacle on regulator, connect red lead from
DMM to socket C. Connect black lead to B– terminal. Does resistance read OL (out of limits)?
Alternator is defective.
(LEDs on N3223 will determine affected output)
Yes
Replace regulator with known good regulator. Run
engine. Does OVCO trip?
Alternator is
defective.
No
14 V side tripped OVCO circuit.
Go to Chart 3a.
No
Yes No
Original regulator
is defective.
Chart 3b – N3107, N3118, N3211, N3223, N3237, N3245 – No 28 V Alternator Output – Test OVCO Circuit
Unplug alternator-to-regulator 4-socket harness from regulator. Connect red lead from DMM to socket A in plug.
Connect black lead to socket D in plug. Does resistance read 1.0 ± 0.2 ohms?
Yes
(28V LED on N3223 steady RED)
No
Alternator is defective.
With red lead from DMM connected to socket A in plug, connect black lead to B– terminal.
Does resistance read OL (out of limits)?
Yes
Replace existing regulator with known good regulator.
Run engine. Does OVCO trip?
Yes
Alternator is defective.
Original regulator is
defective.
No
No
Alternator is defective.
SOCKET CONNECTIONS
A F–
B Phase Signal AC
C B–
D 28 V B+
Figure 8 – Alternator-to-Regulator 4-Socket
Harness Plug
Page 8
TG29D
Section C: Advanced Troubleshooting (CONT’D)
Chart 4 – N1604-all models – No Output
Test for battery voltage across and diagonally between both alternator B+ terminals and alternator Bterminals. Does battery voltage exist?
Yes
Repair vehicle wiring as necessary. Continue test.
No
Install a jumper from anti-drive end B+ terminal on alternator to IGN terminal on regulator. Touch shaft with steel
tool to detect significant magnetism. Is shaft magnetized?
Yes
Repair vehicle circuit to IGN terminal.
Vehicle charging circuit test is complete.
Unplug alternator-to-regulator wiring harness.
Install a jumper from socket A in harness plug
to anti-drive end B– terminal on alternator.
Touch shaft with steel tool to detect significant
magnetism. Is shaft magnetized?
Yes
No
No
Alternator is defective.
Connect DMM across socket D and socket C in
harness plug. Does battery voltage exist?
Yes
No
Alternator is defective.
Using diode tester, attach red lead to alternator
anti-drive end B– terminal and black lead to
socket B in harness. Continuity should exist.
Reverse leads. No continuity should exist.
TG29D
Yes
Regulator is defective.
SOCKET CONNECTIONS
Pin A F–
Pin B AC Terminal
Pin C B–
Pin D B+
Figure 9 – Alternator-to-Regulator Harness Plug
Alternator is defective.
No
Page 9
Section C: Advanced Troubleshooting (CONT’D)
Chart 5 – N1604-all models – No Alternator Output – Test OVCO Circuit
With engine off, unplug alternator-to-regulator harness. Connect DMM red lead to socket A on harness plug.
Connect black lead to alternator anti-drive end B+ terminal. Does resistance measure about 1.0 ± 0.2 ohms?
Yes No
Connect DMM red lead to socket A on alternator-toregulator harness plug. Connect black lead to alternator
anti-drive end B– terminal. Does continuity exist?
Yes
No
Connect DMM red lead to socket A on alternator-to-regulator
Alternator is defective.
harness plug. Connect black lead to alternator case.
Does continuity exist?
Yes
Alternator is defective.
SOCKET CONNECTIONS
Pin A F–
Pin B AC Terminal
Pin C B–
Pin D B+
Alternator is defective.
No
Regulator is defective.
Figure 10 – Alternator-to-Regulator Harness Plug
If you have quest ions about your a lternator or any of these test procedures, or if you need to locate a Factory Authorized Serv ice Dealer, please contact us at:
C. E. Niehoff & Co.• 2021 Lee Street • Evanston, IL 60202 USA
TEL: 800.643.4633 USA and Canada • TEL: 847.866.6030 outside USA and Canada • FAX: 847.492.1242
E-mail us at service@CENiehoff.com
Page 10
TG29D
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