ECU NISSAN ALTIMA HYBRID 2009 L32A / 4.G Dismantling Guide

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Foreword

Nissan released the Altima Hybrid in North America in August of 2007. The Altima Hybrid runs on conventional
gasoline and a traction motor. The basic vehicle systems and features of the Altima Hybrid are the same as
those of the conventional Altima, except where noted in this guide. This Dismantling Guide was published to
help educate and assist the technician in the safe handling of the Altima Hybrid and its technology.

A high voltage battery is used to power the traction motor, generator, electric air conditioning compressor,
voltage converters, and inverter unit. A separate 12 volt battery is used to power other electrical devices such
as the radio, horn, headlamps, and instrument cluste
r gauges. A number of safeguards have been designed to
ensure that the high voltage Nickel Metal Hydride (Ni-MH) battery is kept safe and secure in the event of an
accident.

The Altima Hybrid utilizes both low and high voltage systems:

Low voltage system

• A 12 volt DC negative chassis ground body electrical system

High voltage system

• A 245 volt DC high voltage battery
• A harness that carries high voltage between the high voltage battery, converters, inverter unit, transaxle
and electric air conditioning compressor
• A converter which converts 245 volts DC to 42 volts DC for the electric power steering (EPS) system
• A converter which converts 245 volts DC to 12 volts DC for charging the 12 volt battery
• An inverter unit which delivers up to 650 volts AC to the transaxle
• A transaxle which houses a traction motor and generator
• A 245 volt DC, motor driven electric air conditioning compressor

High voltage electrical safety is an important factor in the dismantling of the Altima Hybrid. It is important to
recognize and understand the disabling procedures and warnings throughout this guide.
Additional topics in this guide include:
• Nissan Altima Hybrid identification
• Hybrid system component locations and descriptions






This Dismantling Guide is intended to assist the technician in the safe handling of a Nissan Altima Hybrid.
The information contained in this guide is somewhat simplified and intended to be used as a technical
reference. Please refer to the Nissan Service Manual for information related to vehicle repair.

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Battery Information

The Altima Hybrid utilizes two batteries in order to supply both low and high voltage.

Low Voltage Battery


The Altima Hybrid contains a lead-acid 12 volt DC low voltage
battery. The low voltage battery is located in the passenger rear
quarter panel well of the trunk and is concealed by a trim cover.
The negative (-) 12 volt battery cable can be accessed through
an access panel in the trim cover.

The 12 volt battery powers the vehicle’s 12 volt electrical
system, similar to a conventional vehicle. As with conventional
vehicles, the 12 volt battery is grounded to the metal chassis of
the vehicle. However, the 12 volt battery is charged by the high
voltage battery through the DC/DC converter.

High Voltage Battery


The Altima Hybrid contains a Ni-MH 245 volt DC high voltage
battery. The high voltage battery is enclosed in a metal case,
which is isolated from high voltage, and is securely mounted in
the trunk area behind the rear seat and is concealed by a trim
cover. The service disconnect can be accessed through an
access panel in the trim cover.

The 245 volt battery powers the vehicle’s high voltage electrical
system. The high voltage battery consists of 34 low voltage (7.2
volt) Ni-MH battery modules connected in series to produce
approximately 245 volts DC. Each Ni-MH battery module is
sealed in a non-spillable plastic case. The electrolyte used in
the Ni-MH battery module is an alkaline mixture of potassium and sodium hydroxide. The electrolyte is
absorbed into the battery cell plates and forms a gel that should not normally leak, even in a collision. In the
unlikely event that the high voltage battery is overcharged, the modules vent gases directly outside the vehicle
through a vent hose.


The high voltage battery supplies power to the following:
• Power cables
• EPS DC/DC converter
• DC/DC converter
• Inverter unit
• Transaxle
• Electric air conditioning compressor

High Voltage Battery Specifications
High voltage battery voltage 245 V
Number of Ni-MH battery modules in the pack 34
Ni-MH battery module voltage 7.2 V
Ni-MH battery module dimensions 5 x 1 x 11 in. (125.5 x 25.1 x 276.1 mm)
Ni-MH module weight 2.2 lbs (1.0 kg)
Ni-MH high voltage battery dimensions 8 x 34 x 19 in. (200.8 x 853.4 x 476.9 mm)
Ni-MH high voltage battery weight 114.6 lbs (52 kg)

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• A ground fault monitor continuously monitors for high voltage leakage to the metal chassis while the
vehicle is running. If a malfunction is detected, the high voltage ECU will illuminate the hybrid system
warning light in the instrument cluster.

• The high voltage battery relays (SMR1 and SMR2) will automatically open to stop the electrical flow in a
frontal collision that is sufficient enough to activate the supplemental restraint system (SRS).