76 Auto Fundamentals
Hybrid Cooling System Precautions
Some hybrid vehicles have an engine coolant
heat storage tank. This tank is insulated and
keeps coolant hot for long periods. The hot cool-
ant is used to warm the cylinder head when the
engine is started cold. Quickly warming the cyl-
inder head reduces hydrocarbon emissions. The
engine coolant heat storage tank could contain
hot, pressurized coolant long after the rest of
the cooling system has reached room tempera-
ture. Always refer to the manufacturer’s service
information before disconnecting any part of a
hybrid cooling system.
Follow Proper Work Procedures
Work procedures are the actual diagnosis
and repair operations. You may be called on to
do all sorts of procedures in your shop classes
or labs. It is vital that you do them safely and
correctly. Improper procedures include using
the wrong tools or methods to perform repairs,
using defective or inappropriate tools, not wear-
ing protective equipment when necessary, and
not paying close attention while performing the
job. Whenever any work is performed, it should
be performed in a safe manner, before any other
considerations. The following safe work proce-
dures may seem to be logical. However, they are
often disregarded, with tragic results.
• Wear proper clothing and use
protective equipment when called for.
• Study work procedures before
beginning any job that is unfamiliar to
you. Do not assume that the procedure
High-voltage cable
Figure 4-7.
When technicians see orange insulation, they can be sure
that they are dealing with high-voltage cables. Hybrid
vehicles use orange insulation for easy identifi cation.
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Figure 4-8.
Before working on the electrical system in a hybrid vehicle, locate and remove the high-voltage disconnect.
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