When test driving the hybrid in the electric mode, it
is best to drive up a small hill. This will increase load on
the motor-generator and draw more current from the bat-
tery pack. Compare battery performance to that of a
known good battery or to specifications. If the battery
pack will not take or hold a charge or output enough cur-
rent for a sufficient amount of drive time in the all-elec-
tric mode, replace the battery pack.
If the battery SOC goes down too quickly when dri-
ving in the all-electric mode, the battery electrolyte and
plates have probably deteriorated due to prolonged service.
If onboard diagnostics and your test drive indicate
poor battery capacity, the entire battery pack must be
replaced. Battery modules should not be replaced indi-
vidually. If one module has failed, others are probably
weak and ready to fail.
If your scan tool indicates high battery temperature,
use an infrared thermometer to compare cell tempera-
tures. The use of an infrared thermometer will help
prevent electrocution, as it does not have to contact the
battery directly. If only one cell runs warm, it is probably
shorted and the battery pack must be replaced. If all the
battery cells are warm, a battery cooling system problem
may exist.
If an air cooling system is used, check for a blower
motor circuit problem or a mechanical problem. If the fan
comes loose from the blower motor, it will not set a
trouble code. Blocked or damaged intake air ducts also
create problems. The vehicle owner may inadvertently
place objects over the battery air intake vent. Ductwork
can also be damaged and restricted during a collision.
Battery Pack Replacement
Hybrid battery packs are usually located in the trunk
area or under the rear seat cushion or floor pan,
Figure 38-27. The most common reason for battery pack
replacement is physical damage. A severe collision can
714 Section 5 Electrical Systems
Figure 38-26. A high-voltage battery charger is needed if the battery pack becomes drained and will no longer start the gas engine.
The battery charger is connected to ground and to the battery pack positive at special service connectors.Then the charger is turned
on to force electrical energy back into battery pack. After charging, test-drive the vehicle to make sure the motor-generator will
charge the battery. (Toyota)
HV
battery
Aux
battery
Battery ECU
connector
Frame
wire
Battery
charger
Frame
wire