C.E. Niehoff & Co. N1245/N1248-3 Troubleshooting Guides - Manual (Page 4)

Page 4 TG44D
Basic Troubleshooting
1. Inspect charging system components for damage
Check connections at B– cables, B+ cables,
B+ interconnect cable, B– interconnect cable, and
alternator-to-regulator harness. Repair or replace
any damaged component before troubleshooting.
2. Inspect all vehicle battery connections
Connections must be clean and tight.
3. 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. In addition, open circuit voltages
must be within ± 0.2 V.
4. Connect meters to alternator
Connect red lead of DMM to alternator anti-drive
end B+ terminal and black lead to alternator
anti-drive end B– terminal. Clamp inductive
ammeter on anti-drive end B+ cable.
5. Operate vehicle
Observe charge voltage at batteries with engine
running (nom. 27-28 V).
If charge voltage is above
32 V, immediately shut
down system. Electrical
system damage may occur if
charging system is allowed
to operate at excessive
voltage. Go to Table 2.
If voltage is at or below regulator setpoint, let
charging system operate for several minutes to
normalize operating temperature.
6. Observe charge volts and amps
Charge voltage should increase and charge amps
should decrease. If charge voltage does not in-
crease within ten minutes, continue to next step.
7. 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:
• N3043—Chart 1, page 5
• N3044 or N3261—Chart 2, page 7
Preliminary Check-out
Check symptoms in Table 3 and correct if necessary.
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 _______________________
Setpoint listed on regulator _____________________
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CAUTION
Section B: Basic Troubleshooting
SYMPTOM ACTION
TABLE 1 – 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; 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: presence of energize signal
to IGN terminal on N3044
or N3261 regulator.
Check: battery voltage at alternator
output terminal.
Check: defective alternator
and/or regulator.
Check: lost residual magnetism in
alternator with N3043
regulator. Go to: Chart 2,
page
7.
Low Voltage Output
High Voltage Output
No Voltage Output