R
Page 4
TG97A
Section B: Basic Troubleshooting
Basic Troubleshooting
1. Inspect charging system components for damage.
Check connections at B– cable, B+ cable, and regulator
harness. Check regulator terminal wiring from regulator
to vehicle components. Repair or replace any damaged
component before electrical troubleshooting.
2. Inspect vehicle battery connections. Connections must
be clean and tight.
3. Determine battery type, voltage, and state of charge.
Batteries must be all the same type. If batteries are dis-
charged, recharge or replace batteries. Electrical system
cannot be properly tested unless batteries are charged
95% or higher. See page 1 for details.
Preliminary Check-out
Check symptoms in Table 1 below and correct if necessar
y.
Required Tools and Equipment
Identification Record
Enter the following information in the spaces provided
for identification records.
Alternator model number:
Regulator model number:
Voltage setpoints listed on regulator:
TABLE 1: Preliminary Charging System Check-Out
CONDITION:
CHECK FOR:
Low Voltage
Output
Low battery state of charge.
Load on system exceeds rated out-
put of alternator.
Faulty wiring or poor ground path.
Faulty alternator or regulator.
Wrong regulator installed.
High Voltage
Output
Faulty regulator.
Faulty alternator.
No Voltage
Output
No energize signal at IGN terminal
on regulator.
Faulty alternator B+ terminal
connection.
Faulty alternator or regulator.
•
Digital Multimeter (DMM)
•
Ammeter (digital, inductive)
•
Jumper wires
4.
Connect meters to alternator:
•
Connect DMM red lead to alternator B+ terminal.
•
Connect DMM black lead to alternator B– terminal.
•
Clamp inductive ammeter onto B+ cable.
5. Operate vehicle and observe charge voltage. Charge
voltage should increase and charge amps should de-
crease. Battery is considered fully charged when charge
voltage is at regulator setpoint and charge amps remain
at lowest value for 10 minutes.
If voltage is at or below regulator setpoint, allow charg-
ing system to operate for several minutes to normalize
operating temperature. If charge voltage does not in-
crease within 10 minutes, go to Chart 1 on page 5.
CAUTION
If voltage exceeds 32 V, shut
down system immediately.
Dam-
age to electrical system may occur if charging
system is allowed to operate above 32 V for more
than 3 seconds.
Check for OVCO Condition
•
Shut down vehicle and restart engine. If alternator func-
tions normally after restart, a no output condition was
normal response of voltage regulator to high voltage
condition.
•
Inspect vehicle electrical system, including loose battery
cables. If battery disconnects from system, it could
cause high voltage condition in electrical system, caus-
ing 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 and shuts off alternator field circuit, go to
Chart 2 on page 6 to test OVCO circuit.
