C.E. Niehoff & Co. C653, C653A, C625 Troubleshooting Guides
C.E. Niehoff & Co.
C653/C653A and C625 Alternators
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.
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 Diagram ................................. 2 – 3
Section B: Basic Troubleshooting .............................4
Section C: A2-146/A2-153 Troubleshooting ..............5
Section D: A2-214 Troubleshooting .................... 6 – 9
Section E: C653 w/A2-338 Troubleshooting ... 10 – 11
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 inten-
sity 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.
TG13G
Page 1
Section A: Wiring Diagrams
CEN C653/C653A and C625 Alternators
Description and Operation
C653/C653A and C625 28 V (260 A) alternators are
self-rectifying. All windings and current-transmitting
components are non-moving, so there are no brushes
or slip rings to wear out.
When controlled by the A2-146 or A2-153 regulator,
these alternators become self-energizing through internal diode trios. Residual magnetic field induces small
voltage in stator and energizes field coil. Field coil continues receiving incremental voltage until full voltage is
achieved. AC is rectified into DC output through diodes.
Regulator controls voltage output. Regulator has:
• D+ terminal to provide a signal to vehicle electrical
system, confirming alternator operation
• P terminal to provide an optional AC voltage tap.
When controlled by the A2-214 regulator, these alter-
nators become externally energized through the IGN
terminal, connected to a switched power source to turn
on regulator. See wiring diagram, Figure 5 on page 3.
Regulator has:
• D+ terminal that can provide signal to vehicle
electrical system, confirming alternator operation.
• P terminal that can provide an optional AC voltage
tap.
• Overvoltage cutout (OVCO). See page 6.
• Green lens LED. See page 6.
When C653 alternator is controlled by the A2-338
regulator, the alternator becomes self-energized through
sensing of alternator rotation through AC circuit.
Residual magnetic field induces small voltage in stator
and energizes field coil. Field coil continues receiving
incremental voltage until full voltage is achieved.
Regulator controls voltage output. See wiring diagram,
Figure 4 on page 3. A2-338 regulator has:
• P terminal that can provide optional AC voltage tap.
• D+ terminal that can provide DC voltage signal to
vehicle electrical system, confirming alternator
operation.
• Overvoltage cutout (OVCO) function. See page 10.
• Tricolored LED. See page 10.
• T terminal to connect optional A9-4011 temperature
sense lead to adjust regulator setpoint to maintain
charge voltage (or negative temperature compensation) by sensing ambient temperature within the
battery box. If temperature sense lead is not connected, the regulator will operate at 27.5 V.
B+ terminal stud
B– terminal
stud
Figure 2 — A2-146 and A2-153 Regulator Terminals
P
terminal
T terminal
(A2-338 only)
IGN terminal
Figure 1 — C625 Alternator Terminals
(Also Used with C653, C653A)
B– terminal
stud
R terminal
D+ terminal
D+ terminal
IGN terminal
(A2-214 only)
P
terminal
D+ terminal
B+ terminal
stud
(on rear of
control unit)
Page 2
C653
ADE View
Figure 3 — C653/C653A Alternator Terminals
C653A
ADE View
TG13G
Section A: Wiring Diagrams (CONT’ D)
P or R
*
REGULATOR
LED
(A2-338 only)
*Thermal switch is not
factory-installed on all models.
T
(A2-338 only)
Figure 4 — C653/C653A Alternators with A2-146 or A2-153 or A2-338 Regulator
IGN
TG13G
*
*Thermal switch is not
factory-installed on all models.
Figure 5 — C653/C653A and C625 Alternators with A2-214 Regulator
LED
P
Page 3
Section B: Basic Troubleshooting
Tools and Equipment for Job
• Digital Multimeter (DMM)
• Ammeter (digital, inductive)
• Jumper wires
Identifi cation Record
List the following for proper troubleshooting:
Alternator model number _________________________
Regulator model number ________________________
Setpoints listed on regulator _____________________
Preliminary Check-out
Check symptoms in Table 1 and correct if necessary.
TABLE 1 – System Conditions
SYMPTOM ACTION
Low Voltage Output
High Voltage Output
No Voltage 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.
Check: lost residual magnetism in
self-energizing alternator.
Go to:
• Chart 1, page 5, for
A2-146/A2-153
• Chart 2, page 7, for
A2-214
• Chart 5, page 11, for
A2-338
Failure to check for the following
NOTICE
conditions will result in erroneous
test results in the troubleshooting
charts.
Basic Troubleshooting
1. Inspect charging system components for damage
Check connections at B– cable, B+ cable, and
regulator harness. Also check connections at
regulator terminal wiring from regulator to vehicle
components. Repair or replace any damaged
component before electrical troubleshooting.
2. Inspect vehicle battery connections
Connections must be clean and tight.
3. Check drive belt
Repair or replace as necessary.
4. 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.
5. 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.
6. Operate vehicle
Observe charge voltage.
If charge voltage is above
32 volts, immediately shut
down system. Electrical
system damage may occur if
charging system is allowed to
operate at high voltage.
Go to Table 1.
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
Charge voltage should increase and charge amps
should decrease. If charge voltage does not
increase within ten minutes, continue to next step.
8. Battery is 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 3, page 8, for A2-214
• Chart 5, page 11, for A2-338
CAUTION
• Chart 1, page 5, for A2-146/A2-153
Page 4
TG13G
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