Jump Starting - Lexus RX400h Towing And Road Service Manual

JUMP-STARTING:
The Lexus RX400h has one battery which is located under the hood. It is positioned on
the right (passenger's) side of the engine compartment behind the right front headlamp
assembly
The RX400h uses the high voltage system to start the gasoline engine. If the 12 volt
battery is discharged, the high voltage system does not function so there may be the need
to jump-start these vehicles.
The following jump-starting procedures should be followed when rendering assistance to
a Lexus RX400h:
• Never use jump-starting equipment that can exceed normal 12-volt charging
system voltage.
• Ensure that all electrical accessories and the ignition switch are turned OFF
before connecting jumper cables or a jumper box to the discharged vehicle.
• If using jumper cables, make connections in the following order:
1. Connect the positive (+) jumper cable to the positive battery terminal of the
discharged vehicle and to the positive (+) battery terminal of the donor vehicle
or jumper box.
2. Connect the negative (-) jumper cable to the negative battery terminal of the
donor vehicle. (Skip this step if using a jumper box.)
3. Connect the negative (-) cable to a good ground on the engine of the
discharged vehicle. NOTE: You may have to remove the decorative engine
cover to access a good connection location.
Allow the discharged battery to charge for a few minutes before attempting start the
vehicle. Since the high voltage system actually starts the gasoline engine, there may not
be any "cranking" that takes place. The computers on this vehicle decide whether or not
the gasoline engine needs to run to charge the high voltage battery which in turn charges
the 12 volt battery through a connection in the system's inverter/converter assembly. The
RX400h usually moves at low speeds and in reverse under electrical power only.
Figure 11
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