After studying this chapter, you will be able to:
Identify the major parts of a hybrid drive system.
Explain the construction and operation of hybrid
drive assemblies.
List the safety measures that must be followed
when working on high-voltage hybrid drive
systems.
Use on-board diagnostics to find the source of
problems in a hybrid vehicle propulsion system.
Identify the most common problems that occur in
a hybrid vehicle drive system.
Perform basic tests to verify hybrid drive trouble
codes.
Safely remove and replace a hybrid battery pack,
power control module, power cables, ECUs, and
motor-generator assemblies
Introduction
A hybrid vehicle (HV) uses two individual power
sources to provide energy for propulsion. A hybrid
gas-electric vehicle (HGEV) has an internal combustion
engine and an electric drive system combined into one
vehicle power train. See Figure 38-1. Since hybrid gas-
electric vehicles are now produced and sold by many
automakers, it is important that you understand how these
vehicles operate and the methods for safely servicing
them. The electrical/electronic service methods you
learned in previous chapters apply to hybrid vehicles. The
primary concern when working on a gas-electric hybrid
drive train is the extremely high voltage and current stored
and generated by the electric drive devices and circuits.
Besides the gas-electric hybrid, automakers are
experimenting with fuel-cell hybrids, hydraulic hybrids,
and pneumatic hybrids. However, none of these experi-
mental drive systems are presently being mass produced
and used in passenger vehicles.
To identify a hybrid vehicle, look for badging on the
front fender, engine cover, or hood. You can also compare
the vehicle’s VIN (vehicle identification number) to fac-
tory reference information. The 5th, 6th, and 7th alphanu-
meric characters in the VIN identify hybrid vehicles.
Hybrid Vehicle History
In 1898, Ferdinand Porsche, the founder of Porsche
Motor Car Company, designed and built a car that used a
small internal combustion engine to spin a large electric
generator. The generator was then used to power electric
motors at each drive wheel. No clutch, transmission, or
694
38andRepairSystemDriveOperationHybrid
Figure 38-1. An internal combustion engine and a powerful
electric drive train are used to propel a hybrid gasoline-electric
vehicle. (Honda)
Motor-generator
Internal
combustion
engine