Section 06: ELECTRICAL
PA1553
22
enough to prevent the batteries from moving, but
they should not be tightened to the point that
excessive strain is placed on the battery
hold-down cover (proper tightening torque: 45-55
lbf-in (5-6 Nm).
To insure good contact, the battery cable ring
terminals should be tight on the battery posts. If
the posts or cable ring terminals are corroded,
the cables should be disconnected and the posts
and clamps cleaned separately with a soda
solution and a wire brush. Install cable ring
terminals on battery posts and tighten to a torque
of 10-15 lbf-ft (13-20 Nm). Replace protective
caps to prevent corrosion and sparks.
3.8 COMMON CAUSES OF BATTERY
FAILURE
When a battery fails, the cause of failure may be
related to something other than the battery. For
this reason, when a battery failure occurs, do not
be satisfied with merely recharging or replacing
the battery. Locate and correct the cause of the
failure to prevent recurrence. Some common
external causes of battery failure are as follows:
1. A defect in charging system such as high
resistance or a faulty alternator or regulator.
2. A malfunction within the 12 volts system
(equalizer).
3. Overloads caused by a defective starter or
excessive use of accessories.
4. Dirt and electrolyte on top of the batteries
causing a constant drain.
5. Hardened battery plates, due to battery
being in a low state of charge over a long
period of time.
6. Shorted cells, loss of active material from
plates.
7. Driving conditions or requirements under
which the vehicle is driven for short periods
of time.
8. A constant drain caused by a shorted circuit
such as an exposed wire or water infiltration
in junction boxes causing ground fault.
9. Extended operation of preheating system
with engine not running.
10. Failing to close disconnect switches during
the night.
3.9 TROUBLESHOOTING
If a battery is known to be good and then has not
performed satisfactorily in service for no
apparent reason, the following factors may
reveal the cause of trouble:
1. Vehicle accessories and disconnect switches
inadvertently left on overnight.
2. Defects in the charging system, such as high
wiring resistance, faulty alternator, regulator
or battery equalizer.
3. A vehicle electrical load exceeding the
alternator (or battery equalizer) capacity, with
the addition of electrical devices, such as CB
radio equipment, a cellular phone or
additional lighting systems.
4. Defects in the electrical system, such as
shorted or pinched wires.
5. Extended driving at a slow speed while using
many accessories.
6. Loose or poor battery cable-to-post
connections, previous improper charging of a
run-down battery, or loose hold-down clamp
bolts.
7. High-resistance connections or defects in the
cranking system.
3.10 "BAT" BATTERY VOLTAGE INCORRECT
TELLTALE LIGHT
If the “BAT" (battery voltage incorrect) telltale
light is illuminated, check the 24-volt voltmeter to
determine if the battery voltage is too high or too
low.
NOTE
According to the battery charging condition, it
is normal that "BAT" telltale light illuminates
upon starting the engine and stays illuminated
for a few seconds. This is caused by the
normal voltage drop of the battery during
starting.
3.10.1 "Bat" Telltale Light Definitions
Voltmeter drops below 24.4 volts dc
o Check alternator output.
o Check voltage regulator.
o Check battery connections.
o Check battery cells.
To Next Page
Loading...
Need help?
General
