C.E. Niehoff & Co. N1450 Troubleshooting Guides - Manual (Page 3)

Page 3
TG57B
Section B: Basic Troubleshooting
4. Connect meters to alternator
Connect red lead of DMM to B+ terminal(s) and
black lead to alternator B– terminal. Clamp induc-
tive ammeter(s) on B+ cable(s).
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 1.
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.
8. If charging system is not performing properly,
go to Chart 1, page 4.
9. Check OVCO circuit
Shut down vehicle and restart engine. If alternator
functions normally after restart, a “no output
condition” was a 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, try third restart. If OVCO
circuit repeats cutout, go to Chart 2, page 5.
Basic Troubleshooting
1. Inspect charging system components for damage
Check connections at B– cable, B+ cables, 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.
SYMPTOM ACTION
TABLE 1 – System Conditions
Check: low battery state of
charge.
Check: current load on system
is greater than alternator
can produce.
Check: defective wiring or poor
ground path; low regu-
lator setpoint.
Check: defective alternator or
regulator.
Check: wrong regulator.
Check: high regulator setpoint.
Check: defective regulator.
Check: alternator.
Check: battery voltage at alter-
nator output terminals.
Check: defective alternator
or regulator.
Low Voltage Output
High Voltage Output
No Output
Preliminary Check-out
Check symptoms in Table 1 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