C.E. Niehoff & Co. C720 Troubleshooting Guides - Manual (Page 3)

Page 3
TG0036A
Basic Troubleshooting
1. Inspect charging system components for
damage
Check connections at B– cable, B+ cable, and
alternator-to-regulator harness. Repair or
replace any damaged component before trouble-
shooting.
2. Inspect all vehicle battery connections
Connections must be clean and tight.
3. Determine battery voltages and states 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.
4. Connect meters to alternator
Connect red lead of DMM to alternator B+ ter-
minal and black lead to alternator B– terminal.
Clamp inductive ammeter on B+ cable.
5. Operate vehicle
Observe charge voltage.
If charge voltage is above
33 volts, immediately
shut down system. Electrical system damage may occur if
charging system is allowed to operate at high voltage. Go to
Table 1 at left.
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.
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 and/
or regulator.
Check: wrong regulator.
Check: high regulator setpoint.
Check: defective regulator.
Check: alternator.
Check: broken drive belt.
Check: battery voltage at alter-
nator output terminal.
Check: defective alternator
and/or regulator.
Check: lost residual magnetism
in self-energizing alternator.
Go to Chart 1, page 4.
Low Voltage Output
High Voltage Output
No Voltage 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
Identification Record
List the following for proper troubleshooting:
Alternator model number ____________________
Regulator model number _____________________
Setpoints listed on regulator __________________
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Section B: Basic Troubleshooting
CAUTION