during disassembly. This prevents the armature from con-
tacting and damaging the magnets and coils in the stator.
A puller is then used to remove the armature, which is
press fit into the end of the engine crankshaft.
Figure 38-34 shows a position sensor for the arma-
ture of a hybrid motor-generator. Since the sensor is fas-
tened to the back of the cylinder block with this model
vehicle, the transaxle and motor-generator must be
removed to service it.
Some hybrids use two or three motor-generators to
provide all-electric drive or electric assist. The motor-
generators can be located inside the transmission or in the
rear drive axle assembly with all-wheel drive vehicles.
Refer to manufacturer service information to replace
these units.
Hybrid Wiring Problems
As with any electrical/electronic circuit, poor elec-
trical connections, broken conductors, shorted wires, and
similar problems can be difficult to diagnose and repair in
a modern hybrid vehicle. When your scan tool shows a
problem with a particular component but the component
tests good, check for wiring problems in the corre-
sponding circuit. Use factory diagrams, like the one
shown in Figure 38-35, to locate any electric connector
or other component that could be affecting the operation
of that circuit.
Summary
• A hybrid gas-electric vehicle has an internal com-
bustion engine and an electric drive system com-
bined into one vehicle power train.
• In a series hybrid configuration, the traction
motor is the only method used to apply torque to
the vehicle’s drive train.
718 Section 5 Electrical Systems
Figure 38-33. Note the major steps for removing one type of motor-generator. This particular unit mounts on the rear of the engine
and in front of the transaxle or transmission. A—The flex plate over the motor-generator can be removed after removing the cap
screws that secure it to the crankshaft flange. B—A plastic sleeve should be installed between the rotor and stator of the motor-gen-
erator assembly. It will keep magnetism from pulling the two together when you are trying to remove the rotor. C—A wheel puller is
then used to force the rotor from the crankshaft. D—With the puller bolted to the rotor, tighten the puller screw to slowly force off the
press fit rotor. (Toyota)
Flex plate
Armature
Plastic
ring
sleeve
Stater
A B C
Puller
Studs
Figure 38-34. This motor rotor position sensor can only be ser-
viced after removing the motor-generator assembly from the
rear of the engine block. (Toyota)
Connector
Cylinder
block
Sensor