N1506 Series Troubleshooting Guide
for N1506-1 Alternators
Hazard Definitions
These terms are used to bring attention to presence of hazards
of various risk levels or to important information concerning
product life.
CAUTION
personal injury or property damage if ignored.
NOTICE
maintenance that are important but not related to
personal injury hazards.
Indicates presence of hazards
that will or can cause minor
Indicates special instructions
on installation, operation or
Table of Contents
Section 1: Wiring Diagram...................................... 2
Section 2: Basic Troubleshooting ........................... 3
Section 3: Advanced Troubleshooting..................4–5
Battery Conditions
NOTICE
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.
Until temperatures of electrical
system components stabilize, these
Charge V olt 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
measured 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 measuring voltage at battery positive terminal or alternator
B+ terminal.
• Surface Charge: A higher than normal battery
voltage 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.
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Page 1
Section 1: Wiring Diagram
CEN N1506-1 Dual Voltage Alternator Description and Operation
N1506-1 100 A (28 /14 V) dual voltage alternator is 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.
N3030 regulator used with these units maintains alternator output voltage at regulated settings as vehicle electrical loads are switched on and off.
Figure 1 — N1506-1Alternator and N3030 Regulator Terminals
Page 2
Figure 2 — N1506-1 Alternator with Regulator
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Section 2: Basic Troubleshooting
A. Tools and Equipment for Job
• Digital Multimeter (DMM)
• Ammeter (digital, inductive)
• Jumper wires
B. Identification Record
List the following for proper troubleshooting:
Alternator model number ____________________
❏
❏
Regulator model number _____________________
❏
Setpoint listed on regulator
D. Basic Troubleshooting
CAUTION
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 connections of vehicle batteries
Connections must be clean and tight.
3. 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 batteries are charged 95% or higher. See page 1 for
details.
Before troubleshooting,
verify correct wiring of
alternator to vehicle.
See Figure 1 for correct
connections to alternator.
Failure to correctly wire
alternator will damage
components or vehicle.
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 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
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 Chart 1, page 4.
Go to Chart 2, page 5.
ACTION
4. Connect meters to alternator
Connect red lead of DMM to alternator 28 V B+
terminal and black lead to alternator B– terminal. Clamp inductive ammeter on 28V B+ cable.
5. Operate vehicle
Observe charge voltage.
CAUTION
If voltage is at or below regulator setpoint, let
charging system operate for several minutes to
normalize operating temperature.
6. Observe charge volts and amps in each circuit
Charge voltage should increase and charge amps
should decrease. If charge voltage does not increase within ten minutes, continue to next step.
7. Batteries are considered fully charged if charge
voltage is at regulator setpoint and charge amps
remain at lowest value for 10 minutes.
8. If charging system is not performing properly,
go to Chart 1, page 4.
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.
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Page 3
Section 3: Advanced Troubleshooting
Chart 1 – No 28V Alternator Output – Test Charging Circuit
With engine off and key on, is battery voltage present at BOTH alternator 28 V and 14 V B+ terminals?
Yes
Repair vehicle wiring as necessary. Continue test.
!!
!
!!
Jumper 28 V B+ terminal on alternator to ENG terminal on regulator. Run engine. Does alternator charge?
Yes
!!
!
Remove jumper wire. Go to ENG terminal on regulator.
With engine running, test for battery voltage going into
ENG terminal from battery. Does battery voltage exist?
Yes
Repair vehicle circuit to ENG terminal.
Vehicle charging circuit test is complete.
!!
!
Run engine and re-test charging circuit for operation.
!!
Connect DMM red lead to pin D on alternator-to-regulator harness plug. Connect black
lead to pin C on same plug. Does battery voltage exist?
Regulator is defective.
!!
Yes
!!
!
!!
!!
!
!!
!!
!
!!
No
Turn off engine, leave key on. Connect jumper
wire from pin A in alternator-to-regulator harness
plug to B– terminal on alternator. Spark will occur.
Touch steel tool to shaft to detect significant
magnetism. Is shaft magnetized?
Yes
!!
!
!!
Alternator is defective.
No
!!
!
!!
No
!!
!
!!
!!
!
!!
No
!!
!
!!
No
!!
!
!!
Alternator is
defective.
Page 4
PIN CONNECTIONS
A
E
B
D
C
Figure 3 – Alternator-to-Regulator Harness Plug
Pin A F–
Pin B SCR Gate
Pin C B–
Pin D 28 V B+
Pin E 14V B+
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Section 3: Advanced Troubleshooting
Chart 2 – No 14 V Alternator Output – Test Circuit
With engine running, does 28 V system charge properly?
Yes
!!
!
!!
With engine off, is battery voltage present at alternator 14 V B+ terminal?
Yes
Repair vehicle wiring as necessary. Continue test.
!!
!
!!
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
!!
!
!!
Substitute a known good regulator. Run engine. Is system
charge voltage at regulator setpoint?
Yes
No
No
!!
!
!!
Go to Chart 1, page 4.
!!
!
!!
No
!!
!
!!
!!
!
!!
No
!!
!
!!
Alternator is defective.
(CONT’D)
!!
!
!!
Original regulator
was defective.
!!
!
!!
Alternator is
defective.
PIN CONNECTIONS
A
E
B
D
C
Figure 4 – Alternator-to-Regulator Harness Plug
Pin A F–
Pin B SCR Gate
Pin C B–
Pin D 28 V B+
Pin E 14V B+
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Page 5
Notes
Page 6
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Notes
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Page 7
Notes
If you have questions about your alternator or any of these test procedures, or if you need to locate a Factory Authorized Service Distributor, please contact us at:
TEL: 800.643.4633 USA and Canada • TEL: 847.866.6030 outside USA and Canada • FAX: 847.492.1242
Page 8
C. E. Niehoff & Co.• 2021 Lee Street • Evanston, IL 60202 USA
E-mail us at support@ceniehoff.com
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