TOYOTA SIENNA 2007 Service Repair Manual

AC–258AIR CONDITIONING – INTEGRATION CONTROL AND PANEL
AC
(c) Remove the screw and the heater blower switch.
7. REMOVE PRINTED WIRE INTEGRATION BOARD
SUB-ASSEMBLY (for Automatic Air Conditioning
System)
(a) Remove the 12 screws and the printed wire
integration board sub-assembly.
8. REMOVE CLOCK ORNAMENT
(a) Remove the clock ornament.
9. REMOVE CENTER CLUSTER MODULE KNOB NO.5
(for Automatic Air Conditioning System)
10. REMOVE CENTER CLUSTER MODULE KNOB NO.6
(for Automatic Air Conditioning System)
I035737
I035738E01
I035741E01

SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEMRS–15
RS
SYSTEM DESCRIPTION
1. GENERAL
(a) In conjunction with impact absorbing structure for a
frontal collision, the SRS (Supplemental Restraint
System) driver airbag and front passenger airbag
were designed to supplement seat belts in the event
of a frontal collision in order to help reduce shock to
the head and chest. This system is a 3-sensor type
airbag system to detect the impact during a frontal
collision using the center airbag sensor assembly
and front airbag sensors. It also operates the airbag
system and seat belt pretensioner.
(b) In order to detect the extent of the collision during
the initial stages of the collision in further detail, the
front airbag sensors have been changed from
mechanical type to electrical type deceleration
sensors. Accordingly, the deployment of the driver
airbag and front passenger airbag is controlled in
two stages according to the severity of the impact.
(c) In conjunction with impact absorbing structure for a
side collision, the front seat side airbag and curtain
shield airbag were designed to help reduce shock to
the driver, front passenger, and rear outer
passengers in the event of a side collision or
rollover.
(d) RSCA (Roll Sensing of Curtain Shield Airbags) is
used in order to deploy the curtain shield airbags
and the seat belt pretensioner for the driver and
front passenger, in the event that the vehicle rolls
over.
(e) The curtain shield airbag that helps reduce shock to
the front and rear seat occupants with a single
curtain shield airbag has been adopted. In
conjunction with this system, the side airbag
sensors have been installed at the bottom of the
center pillars and the rear airbag sensors have been
installed at the bottom of the rear pillars
respectively.
(f) In this system, a front side collision is detected by
the side airbag sensors in order to deploy the front
seat side airbag and curtain shield airbag. A rear
side collision is detected by the rear airbag sensors
and the center airbag sensor assembly in order to
deploy the curtain shield airbag.
(g) The center airbag sensor assembly sends the
airbag deployment signal to the ECM through BEAN
(Body Electronics Area Network) and CAN
(Controller Area Network) to operate the fuel pump
control.
(h) The center airbag sensor assembly sends the
airbag deployment signal to the body ECU via a
discrete line to operate collision door lock release
control.

RS–16SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEM
RS
2. CONSTRUCTION AND OPERATION
(a) FRONT AIRBAG SENSOR
(1) The front airbag sensors are installed on the
right and left radiator supports respectively.
(2) The front airbag sensor uses an electrical type
deceleration sensor.
(3) The deceleration sensor is built into the front
airbag sensor, and the distortion that is created
in the sensor is converted into an electric signal
based on the vehicle deceleration rate during a
frontal collision. Accordingly, the extent of the
initial collision can be detected in detail.
(b) SIDE AIRBAG SENSOR
(1) The side airbag sensors are installed on the
bottom of the right and left center pillars
respectively.
(2) The side airbag sensor uses an electrical type
deceleration sensor.
(3) The deceleration sensor is built into the side
airbag sensor, and the distortion that is created
in the sensor is converted into an electric signal
based on the vehicle deceleration rate during a
front side collision. Accordingly, the extent of the
initial collision can be detected in detail.
(c) REAR AIRBAG SENSOR
(1) The rear airbag sensors are installed on the right
and left rear pillars respectively.
(2) The rear airbag sensor uses an electrical type
deceleration sensor.
(3) The deceleration sensor is built into the rear
airbag sensor, and the distortion that is created
in the sensor is converted into an electric signal
based on the vehicle deceleration rate during a
rear side collision. Accordingly, the extent of the
initial collision can be detected in detail.
(d) CENTER AIRBAG SENSOR ASSEMBLY
(1) General
• The center airbag sensor assembly is
installed on the center floor under the
instrument panel.
• The center airbag sensor assembly consists
of the deceleration sensor, safing sensor,
ignition control circuit and diagnostic circuit.
• The center airbag sensor assembly receives
signals from the deceleration sensor and
safing sensor built into the center airbag
sensor assembly and front airbag sensor and
determines whether or not the driver airbag,
front passenger airbag, and front seat belt
pretensioners should be activated, and
diagnoses system malfunctions.

SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEMRS–17
RS
• The center airbag sensor assembly receives
signals from the deceleration sensor and the
safing sensor built into the center airbag
sensor assembly and the side airbag sensor
and the rear airbag sensor, and determines
whether or not the front seat side airbag and
curtain shield airbag assemblies should be
activated, and diagnoses system
malfunctions.
• The center airbag sensor assembly sends the
airbag deployment signal to the ECM through
BEAN and CAN to operate fuel pump control.
• The center airbag sensor assembly sends the
airbag deployment signal to the main body
ECU through a discrete line to operate
collision door lock release control.
(2) Deceleration sensor and ignition control circuit
• The deceleration sensor is built into the
center airbag sensor assembly, front airbag
sensor, side airbag sensor and rear airbag
sensor, and the distortion created based on
the deceleration of the vehicle during a
frontal, front side or rear side collision is
converted into an electric signal.
• The ignition control circuit performs
calculations based on the signal output from
the deceleration sensors of the center airbag
sensor assembly, front airbag sensor, side
airbag sensor and rear airbag sensor. If the
calculated values are greater than the
specified values, it activates an ignition
operation.
(3) Safing sensor
• The safing sensor is built into the center
airbag sensor assembly. During a frontal
collision, the sensor turns on and outputs an
ON signal to the center airbag sensor
assembly if a deceleration rate greater than
the specified value is applied to the safing
sensor.
(4) Backup power source
• The backup power source consists of a
power supply capacitor and a DC-DC
converter. If the power system does not
function during a collision, the power supply
capacitor discharges and supplies electric
power to the system. The DC-DC converter
operates as a boosting transformer when the
battery voltage falls below a predetermined
level.

RS–18SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEM
RS
(5) Diagnostic circuit
• This circuit constantly diagnoses system
malfunctions. When a malfunction is
detected, it lights up the SRS warning light on
the combination meter assembly to inform the
driver.
(6) Memory circuit
• When a malfunction is detected in the
diagnostic circuit, it is coded and stored in the
memory circuit.
(e) SRS WARNING LIGHT
(1) The SRS warning light is located on the
combination meter assembly. It comes on to
inform the driver of system trouble when a
malfunction is detected in self-diagnosis of the
center airbag sensor assembly. Under normal
operating conditions, when the ignition switch is
turned to the ON position, it comes on for
approximately 6 seconds and then goes off.

SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEMRS–19
RS
3. DEPLOYMENT CONDITION
When the vehicle collides and the shock is greater than
the specified value, the SRS is activated automatically.
The center airbag sensor assembly includes the safing
sensor and deceleration sensor. The safing sensor was
designed to be turned on at a smaller deceleration rate
than the deceleration sensor.
(a) The center airbag sensor assembly determines
whether or not ignition is necessary based on
signals from the deceleration sensor and the front
airbag sensor (*1). If the safing sensor and
deceleration sensor turn on simultaneously, current
flows to the squibs to deploy the SRS as shown in
the illustration below.
HINT:
*1: In case of a front collision, the ignition signal
could be output with the deceleration sensor ON
signal even without a signal from the front airbag
sensor.
C109526E12

RS–20SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEM
RS
(b) The center airbag sensor assembly determines
whether or not ignition is necessary based on
signals from the side airbag sensor. If the safing
sensor and side airbag sensor turn on
simultaneously, current flows to the squib to deploy
the SRS as shown in the illustration below.
(c) The center airbag sensor assembly determines
whether or not ignition is necessary based on
signals from the rear airbag sensor. If the safing
sensor and rear airbag sensor turn on
simultaneously, current flows to the squib to deploy
the SRS as shown in the illustration below (*1).
C109527E03
C109528E03

SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEMRS–21
RS
HINT:
*1: If the front seat side airbag assembly deploys,
the curtain shield airbag assembly will also deploy,
regardless of whether the signal is output from the
rear airbag sensor.
(d) The vehicle is equipped with the function to activate
the SRS in case of vehicle rollover. A circuit to
detect vehicle rollover is built into the center airbag
sensor assembly. When the conditions for vehicle
rollover are met, the SRS is activated as shown in
the illustration below.
H045342E01

RS–22SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEM
RS
HOW TO PROCEED WITH
TROUBLESHOOTING
HINT:
*: Use the intelligent tester.
NEXT
(a) Confirm problem symptoms (See page IN-35).
NEXT
(a) Check if the multiplex communication system DTC is
output (See page MP-14).
HINT:
The center airbag sensor assembly of this system is
connected to the multiplex communication system.
Therefore, before starting troubleshooting, make sure to
check that there is no trouble in the multiplex
communication system.
Result:
B
A
(a) Use the intelligent tester to check if the CAN
communication system is functioning normally (See
page CA-7) .
HINT:
The ECM is connected to the CAN communication
system. Therefore, before starting troubleshooting, make
sure to check that there is no trouble in the CAN
communication system.
Result:
1VEHICLE BROUGHT TO WORKSHOP
2CUSTOMER PROBLEM ANALYSIS
3CHECK MULTIPLEX COMMUNICATION SYSTEM*
Result Proceed to
Multiplex communication system DTC is not
output.A
Multiplex communication system DTC is output. B
INSPECT MULTIPLEX COMMUNICATION
CIRCUIT
4CHECK CAN COMMUNICATION SYSTEM*
Result Proceed to
The CAN communication system is functioning
normally.A

SUPPLEMENTAL RESTRAINT SYSTEM – AIRBAG SYSTEMRS–23
RS
B
A
(a) Proceed to Diagnosis System (See page RS-27).
NEXT
(a) Proceed to DTC Check / Clear (See page RS-35).
Result:
B
A
(a) Proceed to Diagnostic Trouble Code Chart (See page
RS-39).
NEXT
(a) Proceed to Diagnosis System (See page RS-27).
NEXT
(a) Proceed to Problem Symptoms Table (See page RS-23).
NEXT
The CAN communication system is not
functioning normally.B
INSPECT CAN COMMUNICATION CIRCUIT
Result Proceed to
5SRS WARNING LIGHT CHECK
6CHECK FOR DTC*
Result Proceed to
DTC is output. A
DTC is not output. B
GO TO STEP 8
7DIAGNOSTIC TROUBLE CODE CHART
GO TO STEP 10
8SYMPTOM SIMULATION
9PROBLEM SYMPTOMS TABLE