C524 Alternator
Troubleshooting Guide
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 that
CAUTION
will or can cause minor personal
injury or property damage if
ignored.
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 ...............................................................2
Section B: Basic Troubleshooting ......................................3
Section C: Advanced Troubleshooting .........................4 – 5
Battery Conditions
Until temperatures of electrical
NOTICE
system components stabilize, these
conditions may be observed during
cold start voltage tests.
• Maintenance or low maintenance battery:
— Immediately after engine starts, system volts are
lower than regulator setpoint with medium amps.
— 3-5 Minutes into charge cycle, system volts are
higher and amps are dropping.
— 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 characteris tics 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, volts and amps
are still low.
— 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
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 A: Wiring Diagram
CEN C524 Alternator Description and
Operation
C524 14 V (300 A) 3-phase alternator is externally
energized and self-rectifying. All windings and
current-conducting components are non-moving, so
there are no brushes or slip rings to wear out.
After engine is running, regulator receives energize
signal. Regulator monitors alternator rotation and
provides field current only when it detects alternator
shaft rotating at or above idle 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 20 seconds.
A2-334 and A2-335 regulators used with some of
these units are flat temperature compensated. A 15.5
V regulator setpoint is available for battery isolator
applications. Both regulators have a P terminal to
provide an optional AC voltage tap.
IGN terminal
Figure 1 — C524 Alternator/A2-334 Regulator Features
IGN terminal
Regulator
receptacle
LED
P terminal
Figure 2 — A2-335 Remote-mounted Regulator Features
LED
P
terminal
B+
terminal
Page 2
IGN
P
Not used
Figure 3 — C524 Alternator with Regulator
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Section B: Basic Troubleshooting
Tools and Equipment for Job
• Digital Multimeter (DMM)
• Ammeter (digital, inductive)
• Jumper wires
If no tools are available, monitor LED code.
Identifi cation Record
List the following for proper troubleshooting:
Alternator model number ______________________
Regulator model number _____________________
TABLE 1 – System Conditions
SYMPTOM
Low Voltage Output
High Voltage Output
No Voltage 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.
Check: defective alternator
and/or regulator.
Check: defective regulator.
Check: alternator.
Check: presence of energize
signal to IGN terminal on
regulator.
Check: battery voltage at alter-
nator output terminal.
Check: defective alternator
and/or regulator.
ACTION
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 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 batter ies are charged 95% or higher. See page 1 for
details.
4. Connect meters to alternator
Connect red lead of DMM to alternator B+
terminal and black lead to alternator B–
terminal. Clamp inductive ammeter on B+ cable.
5. Operate vehicle
Observe charge voltage.
If charge voltage is above
16 volts, 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.
6. Observe charge volts and amps
Charge voltage should increase and charge amps
should decrease. If charge voltage does not in-
crease within ten minutes, continue to next step.
CAUTION
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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 5.
Page 3
Section C: Advanced Troubleshooting
A2-334 and A2-335 Regulators
DESCRIPTION AND OPERATION
A2-334 regulator is mounted directly to the outside
of the alternator. A2-335 regulator is mounted
remotely on the vehicle and connected to alternator
with extended wiring harnesses.
Main diagnostic feature of regulators consists of a
tricolored (green, amber, red) LED located on the
end of the regulator. The LED works like a voltmeter,
measuring charging voltage. See Table 2 for diagnostic features and LED explanations.
TABLE 2 – Regulator Diagnostics
LED COLOR
AMBER Flashing
Solid
Alternator and regulator operating normally.GREEN Solid
Energize signal present, alternator not rotating
or alternator speed too low for cut-in.
System voltage is lower tha n setpoint—electrical
load exceeds alternator rating at present rotor
speed.
STATUS
ACTION
No action required.
Check drive belt, increase RPM.
When loads decrease or speed increases, LED
should be solid GREEN. If not, check drive belt
and charging system connections.
RED Flashing
CLEAR LED off
System voltage higher than setpoint.
Energize circuit fault.
May occur during normal load switching.
Check for system voltage at IGN terminal on
regulator. If OK, replace regulator. If not OK,
check vehicle wiring and ignition circuit.
Page 4
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Section C: Advanced Troubleshooting
Chart 1 – No Alternator Output – Quick Diagnostic
Remote-mounted regulator applications:
Check condition of fuse in wiring harness before troubleshooting.
With engine running: Does battery voltage exist at alternator B+ terminal and regulator IGN terminal?
B
C
No
No
No
No
No
A
PIN CONNECTIONS
E
Pin A F–
Pin B Phase
D
Pin C GND
Pin D B+
Pin E Not used
Yes
Repair vehicle harness circuit to IGN terminal on
regulator or B+ terminal on alternator.
With key off, engine off: Does battery voltage exist at alternator B+ terminal?
Yes
Repair vehicle harness circuit to B+ terminal on alternator.
With key off, engine off: Unplug alternator-to-regulator harness. Connect DMM on DC volt scale across
pins C and D. Does battery voltage exist?
Yes
Alternator is defective.
With DMM on resistance scale, does the field resistance between pin A in harness plug and
alternator B+ terminal measure about 1.0 (±0.2) ohms?
Yes
Alternator is defective.
Set DMM to diode test.
Check negative diodes: Connect red lead to pin B in harness plug. Connect black lead to alternator B–
terminal. Meter should read OL (over limit). Reverse leads. Meter should read voltage drop.
Check positive diodes: Connect red lead to pin B in harness plug. Connect black lead to alternator B+
terminal. Meter should read voltage drop. Reverse leads. Meter should read OL (over limit).
Yes
Alternator is defective.
With key on, engine off: Momentarily (1 sec.) jumper pin A in
harness plug to alternator B– terminal. Touch shaft with steel
tool to detect significant magnetism. Is shaft magnetized?
Yes
Regulator is defective.
Alternator is defective.
No
Figure 4 – Alternator-to-Regulator Harness Plug
If you have questions about your alternator or a ny of these test procedu res, or if you need to locate a Factory Authorized Serv ice Dea ler, 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
Email: service@CENiehoff.com
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