airbag off TOYOTA SUPRA 1995 Service Repair Manual

CAUTION:
wBe sure to connect both the high and low pressure
quick±connectors onto the A/C system when evacuating.
If only one side is connected, the system would be open
to atmosphere through the other connector, making it
impossible to maintain vacuum.
wBe sure to turn off the manifold gauge valve immediately
after evacuating the system. Then you may switch off the
vacuum pump.
PRECAUTIONS WHEN CHARGING
REFRIGERANT
1. DO NOT OPERATE COMPRESSOR WITHOUT ENOUGH
REFRIGERANT IN REFRIGERANT SYSTEM
If there is not enough refrigerant in the refrigerant system, oil
lubrication will be insufficient and compressor burnout may
occur, so take care to avoid this.
2. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE
WHILST COMPRESSOR IS OPERATING
If the high pressure valve is opened, refrigerant flows in the
reverse direction and could cause the charging cylinder to
rupture, so open and close the low pressure valve only.
3. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH
REFRIGERANT
If refrigerant is overcharged, it causes problems such as in-
sufficient cooling, poor fuel economy, engine overheating
etc.
SUPPLEMENTAL RESTRAINT SYSTEM
(SRS)
Failure to carry out service operations in the correct se-
quence could cause the supplemental restraint system to
deploy, possibly leading to a serious accident.
During removal or installation of the parts and the yellow wire
harness and connector for the airbag is necessary, refer to
the precautionary notices in the RS section before carrying
out operation. AC±6
± AIR CONDITIONING SYSTEMGENERAL DESCRIPTION

OPERATION
FUNCTION OF COMPONENTS
1. STEERING WHEEL PAD (with AIRBAG)
The inflater and bag of the SRS are stored in the steering
wheel pad and cannot be disassembled. The inflater con-
tains a squib, igniter charge, gas generant, etc., and inflates
the bag when instructed by the center airbag sensor assem-
bly.
2. SPIRAL CABLE (in COMBINATION SWITCH)
A spiral cable is used as an electrical joint from the vehicle
body side to the steering wheel.
3. FRONT PASSENGER AIRBAG ASSEMBLY
The inflater and bag of the SRS are stored in the front pas-
senger airbag assembly and cannot be disassembled.
The inflater contains a squib, igniter charge, gas generant,
etc., and inflates the bag when instructed by the center airbag
sensor assembly.
4. SRS WARNING LIGHT
The SRS warning light is located on the cluster finish panel.
It goes on to alert the driver of trouble in the system when a
malfunction is detected in the center airbag sensor assembly.
In normal operating conditions when the ignition switch is
turned to the ACC or ON position, the light goes on for about
6 seconds and then goes off.
5. FRONT AIRBAG SENSOR
A front airbag sensor is mounted inside each of the front fend-
ers. The sensor unit is a mechanical type. When the sensor
detects a deceleration force above a predetermined limit,
contacts is made in the sensor, sending a signal to the center
airbag sensor assembly. The sensor cannot be disas-
sembled. RS±4
± SUPPLEMENTAL RESTRAINT SYSTEMOPERATION

FRONT AIRBAG SENSOR
INSPECTION ITEMS
1. VEHICLES NOT INVOLVED IN A COLLISION
Do a diagnostic system check. (See page RS±44)
2. VEHICLES INVOLVED IN A COLLISION
(a) Do a diagnostic system check.
(See page RS±44)
(b) If the front fender of the car or its periphery is damaged, do
a visual check for damage to the front airbag sensor, which
includes the following items even if the airbag was not
deployed:
wBracket deformation
wPeeling of paint from the bracket
wCracks, dents or chips in the case
wCracks and dents in, or chipping and scratches of the
connector
wPeeling off of the label or damage to the series number
Also refer to the body dimension drawings in the BODY sec-
tion and check the dimensions around where the front airbag
sensors are mounted.
(The SRS may malfunction, or may not work, if the body area
is not repaired or replaced correctly.)
REPLACEMENT REQUIREMENTS
In the following cases, replace the front airbag sensor.
wIf the SRS has been deployed in a collision.
(Replace both the left and right airbag sensors.)
wIf the front airbag sensor has been found to be faulty in
troubleshooting.
wIf the front airbag sensor has been found to be faulty
during the check in item 2±(b).
wIf the front airbag sensor has been dropped.
NOTICE: For replacement of the front airbag sensor, see
page RS±31, ºFRONT AIRBAG SENSOR REMOVAL AND
INSTALLATIONº and be sure to follow the correct proce-
dure. RS±30
± SUPPLEMENTAL RESTRAINT SYSTEMFRONT AIRBAG SENSOR

DIAGNOSIS INSPECTION
SRS warning light check
(a) Turn the ignition switch to ACC or ON and check that the SRS
warning light lights up.
(b) Check that the SRS warning light goes out after approx. 6
seconds.
HINT:
wWhen the ignition switch is at ACC or ON and the SRS
warning light remains on or flashes, the center airbag
sensor assembly has detected a malfunction code.
wIf, after approx. 6 seconds have elapsed, the SRS
warning light sometimes lights up or the SRS warning
light light up even when the ignition switch is OFF, a
short in the SRS warning light circuit can be considered
likely. Proceed to ºSRS warning light systemº on page
RS±97.
Diagnostic trouble code check
Using diagnosis check wire:
1. OUTPUT DIAGNOSTIC TROUBLE CODE
(a) Turn the ignition switch to ACC or ON position and wait
approx. 20 seconds.
(b) Using SST, connect terminals Tc and E
1 of the DLC1 or
DLC2.
SST 09843±18020
NOTICE: Never make a mistake with the terminal connec-
tion position as this will cause a malfunction. RS±44
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

CONNECTORS
Slightly shake the connector vertically and horizontally.
Inspection of connectors
(a) Does the wire harness connecting with its corresponding
part have insufficient slack?
(b) Are the terminals dirty?
(c) Are the terminals making loose contact due to terminals
spread?
WIRE HARNESS
Slightly shake the wire harness vertically and horizontally.
Thoroughly check the connector joint, the fulcrum of the
vibration and the wiring opening in the engine/passenger
compartment panel.
PARTS AND SENSORS
Gently tap the part or sensor considered to be the problem
caused and check if the malfunction will occur.
CAUTION: Do not apply vibration to the center airbag
sensor assembly.
VIBRATION METHOD: When vibration seems to be the major cause.
SYMPTOM SIMULATION
ªIntermittent troubles or problemsº are the malfunctions about which the customer has a complaint, but which
do not occur and cannot be confirmed in the workshop. The intermittent problems also include complaints about
the SRS warning light going on and off erratically.
The self±diagnostic system stores the circuit of the intermittent problem in memory even if the ignition switch
is turned off.
For accurate diagnosis of the problems, ask the customer to obtain as much information as possible following
the customer problem analysis check sheet (See page RS±43) and try to reproduce the intermittent problem.
The problem simulation methods described below are the effective ways to reproduce the problem conditions
by applying vibration, heat, and humidity. RS±48
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

CIRCUIT INSPECTION
DTC (Normal) Source Voltage Drop
CIRCUIT DESCRIPTION
The SRS is equipped with a voltage±increase circuit (DC±DC converter) in the center airbag sensor assembly
in case the source voltage drops.
When the battery voltage drops, the voltage±increase circuit (DC±DC converter) functions to increase the volt-
age of the SRS to normal voltage.
The diagnostic system malfunction display for this circuit is different to other circuits±when the SRS warning light
remains lit up and the diagnostic trouble code is a normal code, voltage source drop is indicated.
Malfunction in this circuit is not recorded in the center airbag sensor assembly, and the voltage source returns
to normal, after approx. 10 seconds the SRS warning light automatically goes off.
 DTC No. Diagnosis 
 (Normal)
 
 Voltage source drop.
RS±52± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

INSPECTION PROCEDURES [P] Preparation [C] Check
(1) Turn ignition switch to LOCK.
(2) Disconnect center airbag sensor assembly con±
nector.
(3) Turn ignition switch ON. But do not start engine.
(4) Measure voltage at IG
2 or ACC on connector
wire harness side of center airbag sensor as±
sembly and operate electric system (defogger,
wiper, headlight, heater blower, etc.).
Voltage: 6 V Ð 11.5 V at IG
2 and ACC.
(5) Turn electric system switch OFF.
(6) Turn ignition switch to LOCK.
(7) Remove voltmeter and connect center sensor
assembly connector.
Preparation.
Does SRS warning light turn off?
Turn ignition switch ON.
Operate electric system checked in [1] (4) and
check that SRA warning light goes off.
Turn ignition switch ON.
Check battery and charging system.
(See charging system section)
Check diagnostic trouble code, and if a malfunc-
tion code is output, perform troubleshooting ac-
cording to malfunction code. If a normal code is
output, replace center airbag sensor assembly.
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±53

DTC 22 SRS Warning Light System Malfunction
CIRCUIT DESCRIPTION
The SRS warning light is located on the cluster finish panel.
When the SRS is normal, the SRS warning light lights up for approx. 6 seconds after the ignition switch is turned
from LOCK position to ACC or ON position, and then turns off automatically.
If there is a malfunction in the SRS, the SRS warning light lights up to inform the driver of the abnormality. When
terminals Tc and E
1 of the DLC1 or DLC2 are connected, the diagnostic trouble code is displayed by the blinking
of the SRS warning light.
The SRS warning light circuit is equipped with an electrical connection check mechanism which detects when
the connector to the center airbag sensor assembly is not properly connected.
If the connector to the center airbag sensor assembly is not properly connected, the SRS warning light will not
light up.
Diagnostic trouble code 22 is recorded when a malfunction occurs in the SRS warning light system. If an OPEN
malfunction occurs in the SRS warning light system, the SRS warning light does not light up, so that until the
malfunction is repaired, the diagnostic trouble codes (including code 22) cannot be confirmed.
 
DTC No. 
Diagnosis 
 
 
22
 
 
 

Open circuit in SRS warning light system.


Center airbag sensor assembly malfunction.
RS±82± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

INSPECTION PROCEDURES [P] Preparation [C] Check
Does SRS warning light turn off?
(1) Turn ignition switch to LOCK.
(2) Disconnect negative (±) terminal cable from the
battery, and wait at least 90 seconds.
(3) Disconnect center airbag sensor assembly
connector.
(4) Connect negative (±) terminal cable to battery.
Check operation of SRS warning light.
Replace center airbag sensor assembly.
Check SRS warning light circuit or terminal AB cir-
cuit of DLC1 or DLC2.
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±97