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.
TG72A
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
TG72A
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