500 Series Troubleshooting Guide
for N1509 and N1511 Alternators
Hazard Defi nitions
These terms are used to bring attention to presence of hazards of
various risk levels or to important information concerning product
life.
Indicates presence of hazards
CAUTION
that will or can cause minor personal
injury or property damage if ignored.
Indicates special instructions
NOTICE
on installation, operation or maintenance that are important but not related to
personal injury hazards.
Table of Contents
Section 1: Wiring Diagram ........................................2
Section 2: Basic Troubleshooting .............................3
Section 3: Advanced Troubleshooting ................ 4 – 8
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 with medium
amps.
— 3-5 minutes into charge cycle, higher system
volts and reduced amps.
— 5-10 minutes into charge cycle, system volts
are at, or nearly at, regulator setpoint, and
amps are reduced to a minimum.
— Low maintenance battery has same charac teristics with slightly longer recharge times.
• Maintenance-free battery:
— Immediately after engine start, system volts
are lower than regulator setpoint with low
charging amps.
— 15-30 minutes into charge cycle, still low volts
and low amps.
— 15-30 minutes into charge cycle, volts increase
several tenths. Amps increase gradually, then
quickly to medium to high amps.
— 20-35 minutes into charge cycle, volts increase
to setpoint and amps decrease.
• 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.
Charge Volt and Amp Values
The volt and amp levels are a function of the battery
state of charge. If batteries are in a state of discharge,
as after extended cranking time to start the engine, the
system volts, when measured after the engine is started
will be lower than the regulator setpoint and the system
amps will be high. This is a normal condition for the
charging system. The measured values of system volts
and amps will depend on the level of battery discharge.
In other words, the greater the battery discharge level,
the lower the system volts and higher the system amps
will be. The volt and amp readings will change, system
volts reading will increase up to regulator setpoint and
the system amps will decrease to low level (depending
on other loads) as the batteries recover and become fully
charged.
• Low Amps: A 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: A system amps value which can
cause the battery temperature to rise above the
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 rates of charge amps.
• High Amps: A system amps value which can cause
the battery temperature to rise above adequate charging temperature within 2-3 hours. To prevent battery
damage the charge amps should be reduced when
the battery temperature rises. Check battery manufacturer’s recommendations for proper rates
of charge amps.
• 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: A 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: A voltage value obtained when measur-
ing voltage at battery positive terminal or alternator
B+ terminal.
• Surface Charge: A higher than normal battery volt-
age occurring when the battery is removed from a
battery charger. The surface charge must be removed
to determine true battery voltage and state of charge.
• Significant Magnetism: A change in the strength or
intensity of a magnetic field present in the 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: A normal condition which
occurs when the load demand on the alternator is
greater than rated alternator output at given rotor
shaft RPM.
TG0014D
Page 1
Section 1: Wiring Diagram
CEN N1509 and N1511 Dual Voltage
Alternator Description and Operation
N1509 and N1511 100 A (28 /14 V) dual voltage
alternators are internally rectified. All windings and
current-transmitting components are non-moving,
so there are no brushes or slip rings to wear out.
Energize switch (commonly an oil pressure switch)
activates regulator. Field coil is then energized. Upper
voltage (28 V) is rectified with standard diodes. Lower
voltage (14V) circuit output current is controlled by
SCRs in the drive end housing. Alternator output current is self-limiting and will not exceed rated capacity
of alternator.
N3207 regulator used with some units:
• maintains alternator output voltage at regulated
settings as vehicle electrical loads are switched
on and off.
• maintains equal voltage across battery terminals
of series-connected batteries.
N2003 load and battery control device (LBCD) used
with these units provides dual-voltage reverse polarity
protection and independant control of battery-charging current.
14 V System
LED Indicator
AC terminal
Figure 1 — N1509 Alternator and N3207 Regulator Termi-
T
T
T
14V
28V
AC
T
E
nals
28 V System
LED Indicator
E terminal
T
T
T
28 V B+
terminal
14 V B+
terminal
B– Terminal
Figure 1 — N1511 Alternator and N3207 Regulator Termi-
nals
Page 2
Figure 2 — N1509 and N1511 Alternators with Regulator
TG0014D
Section 2: Basic Troubleshooting
A. Tools and Equipment for Job
• Digital Multimeter (DMM)
• Ammeter (digital, inductive)
• Jumper wires
If no tools are available, monitor LED code.
B. Identifi cation Record
List the following for proper troubleshooting:
Alternator model number ______________________
T
Regulator model number ______________________
T
Setpoint listed on regulator ____________________
T
T
LBCD model number __________________________
C. Preliminary Check-out
Check symptoms in Table 1 and correct if necessary.
TABLE 1 – System Conditions
SYMPTOM
Low Voltage Output
High Voltage Output
No Voltage Output
No 14 V Output
Check: loose drive belt; low bat-
tery 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
and/or regulator.
Check: wrong regulator.
Check: high regulator setpoint.
Check: defective regulator.
Check: alternator.
Check: presence of energize
signal.
Check: battery voltage at alter-
nator output terminal.
Check: defective alternator
and/or regulator.
Go to “Flashing Amber” in
Table 2, page 6.
ACTION
D . Basic Troubleshooting
1. Inspect charging system components
Check connections at ground cables, positive
cables, and regulator harness. Repair or replace
any damaged component before troubleshooting.
2. Inspect load and battery control device
connections
Connections must be in proper sequence and
clean and tight. See Figure 5, page 7.
3. Inspect connections of vehicle batteries
Connections must be clean and tight.
4. Determine battery type, voltage and state
of charge
Batteries must be all the same type for system
operation. If batteries are discharged, recharge
or replace batteries as necessary. Electrical
system cannot be properly tested unless batter ies are charged 95% or higher. See page 1 for
details.
5. Connect meters to alternator
Connect red lead of DMM to alternator 28 V B+
terminal and black lead to alternator B– termi nal. Clamp inductive ammeter on 28 V B+
cable.
6. Operate vehicle
Observe charge voltage.
If charge voltage is above
33 volts 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
charging system operate for several minutes to
normalize operating temperature.
7. Observe charge volts and amps in each circuit
Charge voltage should increase and charge amps
should decrease. If charge voltage does not in-
crease within ten minutes, continue to next step.
8. Batteries are considered fully charged if charge
voltage is at regulator setpoint and charge amps
remain at lowest value for 10 minutes.
9. If charging system is not performing properly,
go to Chart 1, page 5.
CAUTION
TG0014D
Page 3
Section 3: Advanced Troubleshooting
N3207 Regulator
DESCRIPTION AND OPERATION
N3207 Regulator with OVCO is attached directly to
the outside of alternator. Regulator setpoint has
negative temperature compensation. At 75ºF, the
setting is 28.2 V for 28 V system and 14.1 V for
14 V system.
Main diagnostic feature of N3207 regulator 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) will trip at any of the
following conditions:
• 14 V side trips at voltage higher than regula-
tor setpoint that exists longer than 3 seconds of
reading voltage above 16 V. OVCO feature detects
overvoltage and reacts by signaling relay in F–
alternator circuit to open. This turns off alternator
(14 V LED is steady RED light). OVCO circuit will
reset by either:
— Restarting engine (regulator regains control of
alternator output voltage) OR
— System falling below 11 V. OVCO will auto-
matically reset.
• 28 V side trips at voltage higher than regula-
tor setpoint that exists longer than 2 seconds of
reading voltage above 32 V. OVCO feature detects
overvoltage and reacts by signaling relay in F–
alternator circuit to open. This turns off alternator
(28 V LED is steady RED light). OVCO circuit will
reset by either:
— Restarting engine (regulator regains control of
alternator output voltage) OR
— System falling below 22 V. OVCO will auto-
matically reset.
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.
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 a third
time, check color of LED while engine is running.
28 V RED LED - go to Chart 3, page 6.
14 V RED LED - go to Chart 4, page 6.
LED COLOR STATUS
FLASHING
Green
Amber
Red
STEADY
Red
Page 4
TABLE 2 – N3207 Regulator LED Diagnostics
Regulator is not energized. Measure E terminal voltage. If voltage above 21 V, regulator is defective.OFF
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 5 for 28 V systems, Chart 2 for 14 V systems.
Respective system voltage is above regulated setting. This may occur intermittently with voltage
transients or with system faults.
Alternator is shut down and is not producing power for either voltage. 28 V side trips after
2 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 restarting engine or if system voltage drops
below 22 V or 11 V, respectively. See Chart 3 on page 6 for 28V systems, Chart 4 for 14 V systems.
TG0014D
Section 3: Advanced Troubleshooting
Chart 1 – 28 V LED Flashing AMBER – No 28V Alternator Output – Test Charging Circuit
STATIC TEST – MASTER SWITCH ON, KEY ON, ENGINE OFF
Test for battery voltage at alternator 28 V B+ terminal. Does battery voltage exist?
(CONT’D)
Yes
No
T
Repair vehicle wiring as necessary. Continue test.
T
Jumper 28 V B+ terminal on alternator to E terminal on regulator. Wait 10 seconds. Run engine. Does
alternator charge and is 28 V LED flashing GREEN?
Yes
T
Turn off engine, leave key on. Remove jumper wire. Go to E
terminal on regulator. Test for battery voltage going into E
terminal from battery. Does battery voltage exist?
Yes
No
T
Repair vehicle circuit to E terminal. Vehicle charging circuit test is complete.
T
Run engine and re-test charging circuit for operation.
T
Turn off engine, leave key on. Connect
jumper wire from pin A in harness plug to
B– terminal on alternator. Spark will occur.
Touch steel tool to shaft to detect significant
magnetism. is shaft magnetized?
T
Yes
No
T
No
Alternator is
defective.
T
Test for battery voltage at pin D in harness
plug. Does battery voltage exist?
Yes
No
T
PIN CONNECTIONS
Pin A F–
Pin B SCR Gate
Pin C B–
Pin D 28 V B+
Pin E 14V B+
Pin F AC
Figure 3 – Alternator-to-Regulator Harness Plug
T
Alternator is
defective.
T
Connect DMM red lead to pin C on
harness plug. Connect black leak to alternator B– terminal. Does continuity exist?
Yes
No
T
Alternator is
defective.
T
Set DMM to diode test. Connect DMM red
lead to pin F on harness plug. Connect
black leak to alternator B+ terminal.
Reverse leads. Meter should read OL in
one direction, and voltage drop in the other
direction. Do tests prove out?
Yes
T
Regulator is
defective.
No
T
Alternator is
defective.
TG0014D
Page 5
Section 3: Advanced Troubleshooting
(CONT’D)
Chart 2 – 14 V LED Flashing AMBER – No 14 V Alternator Output – Test Circuit
Run engine. Is 28 V LED on regulator flashing GREEN?
Yes
No
T
With engine off, is battery voltage present at alternator 14 V B+ terminal?
Yes
Go to Chart 1.
T
No
Repair vehicle wiring
as necessary. Continue test.
T
T
Connect DMM red lead to pin E on alternator-to-regulator harness plug.
Connect black lead to pin C on same plug. Does battery voltage exist?
Yes
No
T
Alternator is defective.
T
T
Substitute a known good regulator. Run engine. Is regulator setpoint voltage present and is 14 V LED flashing GREEN?
Yes
T
Original regulator was defective.
Chart 3 – 28 V LED Steady RED– No Alternator Output – Test OVCO Circuit
Alternator is defective.
No
T
Remove 28 V and 14 V positive battery cables AT BATTERY PACK before proceeding.
Unplug alternator-to-regulator harness from regulator. Connect red lead from DMM to socket A in plug.
Connect black lead to socket D in plug. Does resistance read 2.2 ± 0.2 ohms?
Yes
No
T
Alternator is defective.
T
Set DMM to manual ohms scale. Connect red lead from DMM to socket A in plug. Connect black lead to B–
terminal. Does meter read OL (out of limits)? Then connect red lead to socket D and black lead to B– terminal. Does meter read OL (out of limits)?
Yes
T
Reconnect cables. Replace existing regulator with known
good regulator. Run engine. Does OVCO trip?
Yes
No
Alternator is defective.
No
T
T
Alternator is defective.
Chart 4 – 14 V LED Steady RED– No Alternator Output – Test OVCO Circuit
Original regulator is defective.
Run engine. Is 28 V LED on regulator flashing GREEN?
Yes
T
T
Replace regulator with known good regulator. Run engine. Does OVCO trip?
Yes
T
Alternator is defective.
Original regulator is defective.
No
T
Page 6
No
T
Go to Chart 3.
TG0014D
Section 3: Advanced Troubleshooting
N2003 Load & Battery Control Device
DESCRIPTION AND OPERATION
Main diagnostic feature of the LBCD is an LED
display located on the side of the device. The LBCD
monitors alternator output and vehicle electrical
system and regulated voltage. If system voltage falls
below 20.5 volts, N2003 will disconnect batteries
and supply trickle charge. See Table 3 for diagnostic
features and LED display explanations.
TABLE 3 – N2003 Load & Battery Control Device Diagnostics
CHARGING
SYSTEM LED
STATUS
ON
ON
OFF
OFF
N2003 LED
COLOR
Unlit (Clear)
Solid Amber
Solid Green
Solid Red
N2003 STATUS
Alternator not charging.
Alternator RPM below 1500 rpm.
System operating properly. Batteries are
connected to system. Alternator charging.
Batteries are disconnected from system and
battery voltage is less than 24.5 V. Alternator
28 V B+ output terminal is at regulated voltage.
Pin
A
B
C
D
E
TABLE 4 – N2003 Harness Plug
Pin Functions
Function
Battery Ground
Chg. System Indicator Ground Signal
Battery Disconnect Ground Signal
AC In from Regulator AC Terminal
Battery Voltage Sense/Trickle Charge
Figure 4 – N2003
Control Harness Receptacle
LED
24 V Load
24 V Battery
T
12 V Battery
12 V Load
T
T
T
T
TG0014D
Figure 5 – N2003 Load & Battery Control Device
Page 7
Section 3: Advanced Troubleshooting
(CONT’D)
Chart 5 – 28V Only – N2003 Sequence of Operation
DYNAMIC TEST — MASTER SWITCH ON, KEY ON, ENGINE ON
Steady AMBER
Read RPM
Is RPM greater than 1500?
Yes
T
Charging system indicator
LED is “OFF.”
Wait ten seconds.
Read System Voltage
T
Is System Voltage less than 20.5 V?
Yes
T
Steady RED
T
Batteries are disconnected.
T
Read Alternator Voltage
T
Is Alternator Voltage less than 24 V?
Yes
T
Trickle charge
“OFF.”
Trickle charge
“ON.”
T
No
T
Start
T
T
T
T
T
T
No
T
No
T
T
Steady RED
T
Are batteries disconnected?
Yes
T
Connect batteries and
then go back to
“Read System Voltage”
above
LBCD is defective. Replace.
Steady GREEN.
System is operating
properly.
No
T
T
Read Battery Voltage
T
T
Is Battery Voltage more than 24.5 V
for one time and one time only?
Yes No
T
Batteries are reconnected.
Steady GREEN.
System is operating properly.
If you have questions about your alternator or any of these test procedures, or if you need to locate a Factory Authorized Service Dealer, please contact us at:
Page 8
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 OR visit our Web site at www.CENiehoff.com
C. E. Niehoff & Co.• 2021 Lee Street • Evanston, IL 60202 USA
TG0014D
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