600 Series Troubleshooting Guide
for C622 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.
DANGER
death or substantial property damage if ignored.
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 cause severe personal inury,
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 – 7
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 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.
TG0011A
Page 1
Section 1: Wiring Diagram
CEN C622 Alternator
Description and Operation
C622 28 V 100 A/84 V 50 A alternator is internally
rectified. All windings and current-transmitting
components are non-moving, so there are no brushes
or slip rings to wear out. This unit is externally
energized through an energize switch (commonly an
oil pressure switch), which activates regulator. Field
coil is then energized. 84 V system is not energized
until 28 V system is energized. 84 V and 28 V circuit
output currents are controlled by separate SCRs in
the drive end housing. Alternator output current is
self-limiting and will not exceed rated capacity of
alternator.
A2-307 regulator used with these units:
• maintains alternator output voltage at regulated
settings as vehicle electrical loads are switched
on and off.
• monitors 28 V and 84 V systems separately.
A2-604 battery charge equalizer and A9-069 harness
used with these units:
• equalizes six 12 V batteries connected in series.
• turns on when charge voltage is above 78 volts.
84 V LED
Indicator
28 V B+
Terminal
Tricolor
diagnostic LEDs
(2 side-by-side)
TT
T
TT
84 V 28 V
A2-307 Regulator LEDs
TT
T
TT
TT
TT
T
TT
T
TT
NEG 84 V terminal
28 V E Terminal
TT
T
TT
TT
T
TT
T
TT
TT
POS 84 V terminal
TT
T
TT
28 V LED
Indicator
28 V B– Terminal
(either side)
DANGER
system. Severe personal injury or death will result from contact.
HIGH VOLTAGE. Use extreme
caution when working around 84 V
Figure 1 — C622 Alternator Terminals
Page 2
Figure 2 — C622 Alternator with Regulator
TG0011A
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 ___________________
❏
Battery charge equalizer model number _______
❏
Harness 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 84 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 “Steady Amber” in
Table 2, page 4.
ACTION
D. Basic Troubleshooting
DANGER
system. Severe personal injury or death will result from contact.
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 battery charge equalizer connections
Connections must be in proper sequence and
clean and tight. See Figure 4, page 6.
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 batteries 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 28 V B–
terminal. Clamp inductive ammeter on 28 V B+
cable.
6. Operate vehicle
Observe charge voltage.
CAUTION
or 85 V for 84 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 increase 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 3, page 7.
HIGH VOLTAGE. Use extreme
caution when working around 84 V
If charge voltage is above
33 volts for 28 V system
TG0011A
Page 3
Section 3: Advanced Troubleshooting
A2-307 Regulator
DESCRIPTION AND OPERATION
A2-307 Regulator with OVCO is attached directly to
the outside of alternator. Set point of temperature
compensation regulator is 82.0 V.
Main diagnostic feature of A2-307 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 84 V
system performance. The two LEDs work independently of each other, not in combination with each
other. See Table 2 for diagnostic features and LED
explanations.
OVCO (overvoltage cutout) will trip at any of the
following conditions:
• 28 V side trips at voltage higher than regulator
setpoint that exists longer than 2 seconds of
reading voltage above 32 V. OVCO feature detects
high voltage and reacts by signaling relay in F+
alternator circuit to open. This turns off alternator (28 V LED is steady RED light). Restarting
engine resets OVCO circuit. Regulator regains
control of alternator output voltage.
• 84 V side trips at voltage higher than regulator
setpoint that exists longer than 2 seconds of
reading voltage above 85 V. OVCO feature detects
high voltage and reacts by signaling relay in F+
alternator circuit to open. This turns off alternator (84 V LED is steady RED light). Restarting
engine resets OVCO circuit. Regulator regains
control of alternator output voltage.
TROUBLESHOOTING
DANGER
system. Severe personal injury or death will result from contact.
HIGH VOLTAGE. Use extreme
caution when working around 84 V
Shut down vehicle and restart engine. If alternator
functions normally after restart, a “no output condition” was normal response of voltage regulator to
“high voltage” condition. Inspect condition of electrical system, including loose battery cables, both
positive and negative. If battery disconnects from
system, it could cause “high voltage” 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, high voltage spike,
causing 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 1, page 5.
84 V RED LED - go to Chart 2, page 5.
LED COLOR STATUS
OFF
FLASHING (once per second
for respective system voltage)
Green
Amber
Red
STEADY
Amber (84 V LED Only)
Red
FAST FLASHING RED
(at least two times per second
for respective system voltage)
Page 4
TABLE 2 – A2-307 Regulator Diagnostics
Regulator is not energized. Measure E terminal voltage. If voltage above 21 V, regulator is
defective.
Respective system voltage is at regulated setting and operating under control.
Respective system voltage is below regulated setting. Alernator is not producing power or circuit
is overloaded.
Respective system voltage is above regulated setting. This may occur intermittently with voltage
transients or with system faults.
Alternator is producing only 28 V output current. This will occur if 84 V batteries are disconnected. Regulator remains in this mode until reset by restarting engine.
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. 84 V side trips after 2 seconds of reading voltage above
85 V. Regulator remains in this mode until reset by restarting engine.
Indicates regulator redundant control is lost. Service as soon as possible for alternator,
regulator or wiring fault. High side voltage will continue to produce 84 V, but low voltage side
will default to 26 V regulation to alert operator of control malfunction. Regulator remains in
this mode until reset by restarting engine. See Chart 1, page 5.
TG0011A
Section 3: Advanced Troubleshooting
(CONT’D)
Chart 1 – 28 V RED LED On Steady – No Alternator Output – Test OVCO Circuit
Make sure batteries are properly charged before proceeding.
Disconnect ground cable from 28 V battery pack. Unplug alternator-to-regulator harness from regulator.
Connect red lead from DMM to socket S in plug. Connect black lead to alternator 28 V B+ terminal. Does
resistance read 2.2 ± 0.2 ohms?
Yes
TT
T
TT
Disconnect cable from alternator 28 V B+ terminal. Set DMM to ohms
scale. Connect red lead from DMM to socket S in plug. Connect black lead
to 28 V B– terminal. Does meter read OL (out of limits)?
Yes
Alternator is defective.
TT
T
TT
Reconnect cables. Replace existing regulator with known good regulator. Run engine. Does OVCO trip?
Yes
No
No
TT
T
TT
No
TT
T
TT
Alternator is defective.
TT
T
TT
Alternator is defective.
Chart 2 – 84 V RED LED On Steady – No Alternator Output – Test OVCO Circuit
Make sure batteries are properly charged before proceeding.
Replace regulator with known good regulator. Run engine. Does OVCO trip?
Alternator is defective.
TT
T
TT
Original regulator is defective.
DANGER
system. Severe personal injury or death will result from contact.
Yes
TT
T
TT
HIGH VOLTAGE . Use extreme
caution when working around 84 V
No
TT
T
TT
Original regulator is defective.
TG0011A
Page 5
Section 3: Advanced Troubleshooting
(CONT’D)
A2-604 Battery Charge Equalizer and A9-069 Harness
DESCRIPTION AND OPERATION
A2-604 Battery Charge Equalizer is attached directly to the battery
compartment.
Main diagnostic feature of A2-604 equalizer is an LED display located
on the front of the equalizer. The equalizer measures battery charge
voltage and “equalizes” battery voltage to prevent overcharge. See
Table 3 for diagnostic features and LED display explanations.
TABLE 3 – A2-604 Battery Charge Equalizer Diagnostics
DISPLAY STATUS
0
1, 2, 3,
4, 5 or 6
in rotation
Flashing
one number
(not “0”)
C
(unlit)
DANGER
All batteries are equalized.
Number represents series location of battery that is at
least 0.4 V higher than the others. Number will change
frequently during operation.
Number represents series location of battery that is
continuously overcharged. Perform battery tests to
determine problem. Replace batteries as necessary.
Connections are in wrong position or at least one of the
wires is disconnected.
Equalizer is off.
Do not allow batteries to overcharge. Battery can
explode, resulting in severe personal injury, death or
substantial property damage.
TABLE 4 – A9-069 Harness Plug
Pin Functions
Pin
A
B
C
D
E
F
G
Figure 3 – A9-069
Harness Plug
Function
12 V
24 V
36 V
48 V
60 V
72 V
0.0 V
Battery #
1
2
3
4
5
6
N/A
Page 6
DANGER
system. Severe personal injury or death will result from contact.
Figure 4 – A9-069 Harness Connections
HIGH VOLTAGE. Use extreme
caution when working around 84 V
TG0011A
Section 3: Advanced Troubleshooting
Chart 3 – No Alternator Output – Test Charging Circuit
STATIC TEST – ENGINE OFF, BATTERY SWITCH ON, KEY ON
Test for battery voltage at alternator 28 V B+ terminal. Does battery voltage
exist?
Ye s
Repair vehicle wiring as necessary. Continue test.
TT
T
TT
Jumper 28 V B+ terminal on alternator to E terminal on regulator. Touch shaft with steel tool to detect
significant magnetism. Is shaft magnetized?
No
TT
T
TT
TT
T
TT
Yes
TT
T
TT
Go to energize switch on engine in E circuit. Test for
battery voltage going into energize switch from battery.
Does battery voltage exist?
Ye s
Repair vehicle circuit to
energize switch. Continue test.
TT
T
TT
Make sure jumper wire from alternator 28 V B+ terminal to regulator E terminal is still attached.
Test for battery voltage at energize switch E terminal
connection. Does battery voltage exist at energize
switch?
Yes
TT
T
TT
E circuit from regulator to
energize switch is good.
Energize switch is defective.
Repair vehicle circuit
from E terminal on
regulator to energize
switch on engine.
No
TT
T
TT
TT
T
TT
No
TT
T
TT
No
TT
T
TT
Connect jumper wire from socket S in alternator-to-regulator harness plug to 28 V B–
terminal on alternator. Spark will occur.
Touch shaft with steel tool to detect significant magnetism. Is shaft magnetized?
Yes
TT
T
TT
Disconnect jumper wire. Connect DMM red
lead to socket J in alternator-to-regulator
harness plug. Connect black lead to socket H in
same plug. Does battery voltage exist?
Yes
TT
T
TT
Regulator is
defective.
No
TT
T
TT
Alternator is
defective.
No
TT
T
TT
Alternator is
defective.
TT
T
TT
Vehicle charging circuit test is complete. Remove
jumper wire used in testing. Run engine and re-test
charging circuit for operation.
TT
T
TT
TG0011A
SOCKET CONNECTIONS
Pin G, F, E 84 V Phase
Pin R, Q, P 84 V SCR Gate
Pin D 84 V NEG
Pin C 84 V POS
Pin S F –
Pin J 28 V B+
Pin H 28 V B –
Pin B, A, K 28 V Phase
Pin M, L, T 28 V SCR Gate
Figure 5 – Alternator-to-Regulator Harness Plug
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
TG0011A
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