C.E. Niehoff & Co. C629 Troubleshooting Guides

C.E. Niehoff & Co.

Before troubleshooting any CEN products, the service technician should:

WARNING

• read, understand, and agree to follow all information contained in this troubleshooting guide.

• understand the operational characteristics of the electrical charging system components to be tested.

• be profi cient at the use of tools and test equipment used in troubleshooting CEN products.

On-Vehicle Troubleshooting Guide

C629 Alternator

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 hazard(s) that

WARNING

can cause severe personal injury,
death, or substantial property
damage if ignored.

Indicates presence of hazards that

CAUTION

will or can cause minor personal
injury or property damage.

Table of Contents

Section A: Alternator and Regulator ............................ 2

Section B: On-Vehicle Troubleshooting ...................... 3-4

Tools and Equipment

• Digital Multimeter (DMM)

• Ammeter (digital, inductive)

• Jumper wires

• CEN 6-pin Metri-Pack Inline Harness Test Tool A10-114

Figure 1—CEN 6-pin Metri-Pack Inline Harness

Test Tool A10-114

Testing Guidelines

Professional service technicians rely on the following
guidelines when testing electrical components.

Voltage testing:

• Set meter to proper scale and type (AC or DC).

• Be sure to zero the meter scale or identify the meter
burden by touching meter leads together. Meter bur­den must be subtracted from final reading obtained.

• Be sure the meter leads touch source area only.
Prevent short circuit damage to test leads or source
by not allowing meter leads to touch other pins or
exposed wires in test area.

• Be sure to use CEN tools designed especially for
troubleshooting CEN alternators when available.
See page 1 for more information.

Resistance (ohm) testing:

• Set meter to proper scale.

• Be sure to zero the meter scale or identify the meter
burden by touching meter leads together. Meter bur­den must be subtracted from final reading obtained.

• Be sure the meter leads touch source area only.
Prevent altering the reading by not allowing fingers
or body parts to touch meter leads or source during
reading.

• Be sure reading is taken when source is at 70ºF.
Readings taken at higher temperatures will increase
the reading. Conversely, readings taken at lower
temperatures will decrease the reading.

• Be sure to test directly at the source. Testing through
extended harnesses or cable extensions may increase
the reading.

Voltage drop testing:

• Measure voltage between B+ on alternator or source
and B- (ground) on alternator or source. Record
obtained reading. Move to batteries or other source
and measure again between B+ and B- terminals on
battery or other source. Difference between the two
readings represents voltage lost within the circuit
due to but not limited to inadequate cable gage or
faulty connections.

• Voltage drop measurements must be taken with
all electrical loads or source operating.

Dynamic/Live testing:

Definition: Connecting power and ground to a
component to test operation/function out of circuit.

1. Be sure to connect jumper leads directly and securely
to source contacts of the component being tested.

2. Be sure to make any connection to power and ground
at the power supply or battery source terminals. Do
not make connection at component source terminals
as that may create an arc and damage component
source terminals.

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Page 1

Section A: Alternator and Regulator

CEN C629 Alternator/Regulator Description and Operation

C629 28 V (260 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 alternator is externally energized when the battery master switch on the vehicle is turned on and provides
power to the regulator through the IGN circuit.

Field coil is then energized. AC is rectified into DC output through diodes in drive end rectifier housing and supplied
to the battery from the alternator B+ terminal. See schematic diagram on page 3. Alternator output current is self-limit­ing and will not exceed rated capacity of alternator. Regulator maintains alternator output voltage at pre-determined
regulated setting (see Table 1 below for setpoints) as vehicle electrical loads are switched on and off.

Battery type selection and battery maintenance/function are the sole responsibilities of the customer.

A2-216 regulator furnished with some units include:

• External IGN terminal for energize connection.

• D+ terminal that can provide DC voltage signal to vehicle electrical system, confirming alternator operation.

• Overvoltage cutout (OVCO) function. See page 3.

• Green-lensed LED. See page 3.

• Regulator fixed (flat temperature compensation) setpoints shown in Table 1 are selected based on battery type.

Table 1— Voltage Setpoint Switch Position

Voltage Setpoints (±0.2 V) Battery Type*

Position 1 27.5 V Maintenance

Position 2 28.0 V Maintenance

Position 3 28.5 V Maintenance-free

Position 4 29.0 V Maintenance-free

* Setpoint can depend on temperature or climate condition, as well as
battery type. If boiling or excessive gassing occurs with higher voltage
setpoint, change to next lower voltage setpoint.

Figure 2—Voltage Setpoints

Page 2

B+ Terminal

B− Terminal

D+ Terminal

Figure 3—Alternator with A2-216 Regulator

IGN terminal

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Section B: On-Vehicle Troubleshooting

A2-216 Regulator Troubleshooting

A2-216 regulator is either attached directly to the
outside of alternator.

Main diagnostic feature is a green lens LED located on
the front of the regulator. LED indicates whether regula­tor has been energized. See Table 2 for LED indication
and status.

Regulators with OVCO (overvoltage cutout) will trip at
vehicle electrical system voltages above 32 volts that
exist longer than 3 seconds. OVCO feature detects high
voltage and reacts by signaling the alternator field
circuit to open. This turns off alternator. Restarting
engine resets OVCO circuit. Regulator regains control
of alternator output voltage.

TABLE 2 — A2-216 Regulator

LED Indications and Status

INDICATION STATUS

ON steady Normal regulator operation.

Alternator is producing output.

FLASHING Regulator is receiving energize

signal. LED will fl ash until
alternator produces output.

OFF Regulator is not receiving energize

signal or OVCO has tripped.

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R

R

BR

BR

G

Figure 4—Alternator Schematic Diagram

Page 3

Section B: On-Vehicle Troubleshooting (CONT’D)

No Alternator Output – Test Charging Circuit

• BEFORE STARTING DIAGNOSTIC SEQUENCE, VERIFY THE FOLLOWING AND REPAIR/REPLACE IF NOT
TO SPEC:
—BATTERIES FOR STATE-OF-CHARGE (24.5-25.5 V), CONDITION, AND SECURE CONNECTIONS
—MASTER BATTERY SWITCH FOR FUNCTION

MASTER BATTERY SWITCH ON, KEY ON, ENGINE ON: Test for battery voltage at B+ terminal on alternator
to ground, then at IGN terminal on regulator to ground.

Yes

Repair vehicle wiring as necessary. Run engine
and re-test charging circuit. Is charging system
performing properly?

No

ENGINE OFF: Disconnect 6-pin alternator-to-regulator harness plug at
regulator and connect CEN A10-114 inline test tool to harness plug end only.
Make sure connections are secure.

No

Yes

System is operative.

MASTER BATTERY SWITCH ON, KEY OFF, ENGINE OFF: Readings of all five tests must pass.

1. Battery voltage test: Connect DMM red lead to socket D in test tool. Connect DMM black lead to socket C in test
tool. Battery voltage should exist.

2. Field coil resistance test: Set DMM to ohms test. Field resistance between socket F and C in test tool should mea­sure nominal 1.0-1.5 ± 0.2 ohms. Field coil is defective if reading is less than 0.5 ohms or greater than 3 ohms.

3. Significant magnetism test:
a. Securely connect one end of a jumper wire to socket F in test tool.
b. Momentarily (1 sec.) touch other end of jumper wire to alternator B+ terminal. Spark will occur at B+ terminal.
Touch steel tool to shaft to detect significant magnetism.

4. Turn off master battery switch. Disconnect B+ battery cable on alternator. Set DMM to diode test. Connect black
lead on DMM to socket E in test tool and red lead to B+ terminal on alternator. DMM should read OL. Reverse
leads. DMM should read OL again. Reconnect B+ battery cable to alternator. Turn on master battery switch.

5. Phase taps test: Set DMM to diode test. Connect DMM black lead to socket B in test tool. Connect red lead to
alternator B+ terminal. DMM should read blocking in this direction. Then reverse leads. DMM should read f low
in this direction. Repeat for socket B and B– terminal. Tests should read flow in one direction and blocking in
the other direction.

Yes

Regulator is defective.

Alternator is defective.

No

SOCKET CONNECTIONS

Socket A Not used
Socket B Phase
Socket C B –
Socket D B+
Socket E D+
Socket F F+

F

A

E

B

C

D

Figure 5 – CEN 6-pin A10-114 Inline Harness Tool

Socket Connections

If you have questions about your a lternator or a ny of these test procedures, or if you need to locate a Factory Authorized Service Dealer, please contact us at:

Page 4

TEL: [phone] USA and Canada • TEL: [phone] outside USA and Canada • FAX: [phone]

C.E. Niehoff & Co.• 2021 Lee Street • Evanston, IL 60202 USA

E-mail us at [e-mail]

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