C.E. Niehoff & Co. N1387-1/EPM Troubleshooting Guides - Manual (Page 5)

Page 5
TG0019A
C. 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 EPM connections
Connections must be in proper sequence and
clean and tight. See Figure 9, page 10.
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 batter-
ies 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 B– termi-
nal. Clamp inductive ammeter on 28 V B+
cable.
6. Operate vehicle
Follow start-up procedure on Page 2. Observe
charge voltage.
If charge voltage is above
33 volts for 28 V system
or 16 V for 14 V system, immediately shut down system.
Electrical system damage may occur if charging system
is allowed to operate at excessive voltage. Go to page 9.
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 in-
crease 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 1, page 7.
A. Tools and Equipment for Job
• Digital Multimeter (DMM)
• Ammeter (digital, inductive)
• Jumper wires
If no tools are available, monitor LED code.
B. Identification Record
List the following for proper troubleshooting:
Alternator model number ____________________
Regulator model number _____________________
Setpoint listed on regulator ___________________
EPM model number __________________________
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Section 4: Basic Troubleshooting
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CAUTION
SYMPTOM ACTION
TABLE 4 – System Conditions
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.
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.
Check:defective regulator.
Check:cable from 14 V regulator
terminal to battery.
Low Voltage Output
High Voltage Output
No Voltage Output
No 14 V Output