sensor TOYOTA SUPRA 1995 Service Repair Manual

CENTER AIRBAG SENSOR ASSEMBLY CONNECTOR
 No. Symbol Terminal Name
 A ±± Electrical Connection Check Mechanism
 B ±± Electrical Connection Check Mechanism 
 1
 
 P± 
 Squib  (Front Passenger)
 2 P+ Squib
(Front Passenger)
 3 D+ Squib
(Driver)
 4 D± Squib  (Driver) 
 5
 
 E1
 
 Ground
 6 E2 Ground
 7 Tc Diagnosis
 8 +SL Front Airbag Sensor LH
 
 9
 
 ±SL
 
 Front Airbag Sensor LH 
 10 ±SR Front Airbag Sensor RH 
 11 +SR Front Airbag Sensor RH

 12 LA SRS Warning Light 
 13 
 IG2
 
 Power Source (IGN Fuse)
 14 ACC Power Source (CIG Fuse)
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±51

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 11 Short in Squib Circuit or Front Airbag Sensor Circuit (to
Ground)
CIRCUIT DESCRIPTION
The squib circuit consists of the center airbag sensor assembly, spiral cable, steering wheel pad and front pas-
senger airbag assembly. It causes the SRS to deploy when the SRS deployment conditions are satisfied.
The front airbag sensor detects the deceleration force in a frontal collision and is located in the front fender on
the left and right sides.
For details of the function of each component see FUNCTION OF COMPONENTS on page RS±4.
Diagnostic trouble code 11 is recorded when ground short is detected in the squib circuit or front airbag sensor
circuit.
 
 DTC No.
 
 Diagnosis
 
 
 
 
 
 
11
 
 
 
 
 
 

Short circuit in squib wire harness (to ground).


Squib malfunction.


Short circuit in front airbag sensor + S wire harness (to ground).


Front airbag sensor malfunction.


Short circuit between + S wire harness and ± S wire harness of front airbag sensor.


Spiral cable malfunction.


Center airbag sensor assembly malfunction.
RS±54± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

(1) Disconnect negative (±) terminal cable from the
battery, and wait at least 90 seconds.
(2) remove steering wheel pad (See page RS±10).
(3) Disconnect connector of front passenger airbag
assembly (See page RS±20).
Preparation.
Check front airbag sensor circuit. (Measure resistance between terminals +SR and
ÐSR, +SL and ÐSL of center airbag sensor assembly connector.)
Disconnect center airbag sensor assembly connec-
tor.
Measure resistance between terminals +SR and
ÐSR, +SL and ÐSL of harness side connector of
center airbag sensor assembly.
Resistance: 744  Ð 885 
Repair or replace harness or connector between
center airbag sensor assembly and front airbag
sensor.
Store the steering wheel pad with the front surface
facing upward.
Check front airbag sensor circuit. (Measure resistance between terminals +SR,
+SL of center airbag sensor assembly connector and body ground.)
Measure resistance between terminals +SR, +SL of
harness side connector of center airbag sensor as-
sembly and body ground.
Resistance: 1 MHigher
INSPECTION PROCEDURES [P] Preparation [C] Check
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±55

For the connector (on the spiral cable side) between
the spiral cable and steering wheel pad, measure
the resistance between D
+, D± and body ground.
Resistance: 1 M or Higher
Check D squib circuit.
Check P squib circuit.
For the connector (on the center airbag sensor as-
sembly side) between the center airbag sensor as-
sembly and front passenger airbag assembly, mea-
sure the resistance between P
+, P± and body
ground.
Resistance: 1  or Higher
Repair or replace harness or connector between
center airbag sensor assembly and front airbag
sensor.
RS±56± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

Check center airbag sensor assembly.
(1) Connect connector to center airbag sensor as±
sembly.
(2) Using a service wire, connect D
± and D± on spiral
cable side of connector between spiral cable and
steering wheel pad.
(3) Using a service wire, connect P
+ and P± on cen±
ter airbag sensor assembly side of connector
between center airbag sensor assembly and
front passenger airbag assembly.
(4) Connect negative(±) terminal cable to battery,
and wait at least 2 seconds.
(1) Turn ignition switch to ACC or ON and wait at
least 20 seconds.
(2) Clear malfunction code stored in memory
(See page RS±47)
(3) Turn ignition switch to LOCK, and wait at least
20 seconds.
(4) Turn ignition switch to ACC or ON, and wait at
least 20 seconds.
(5) Using SST, connect terminals Tc and E
1 of
DLC1 or DLC2.
SST 09843±18020
(6) Check diagnostic trouble code.
Diagnostic trouble code 11 is not output.
Codes other than code 11 may be output at this time,
but they are not relevant to this check.
Replace center airbag sensor assembly.
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±57

Check front airbag sensor.
Replace front airbag sensor.
Disconnect front airbag sensor connector.
Measure resistance between each terminal of front
airbag sensor.

Do not press ohmmeter probes too strongly
against terminals of front airbag sensor.

Make sure the front airbag sensor connector
is properly connected.
Repair or replace harness or connector between center airbag sensor assembly and front airbag
sensor (See page RS±36).
Disconnect connector between center airbag sen-
sor assembly and spiral cable.
Measure resistance between D+, D± on spiral cable
side of connector between spiral cable and steering
wheel pad and body ground.
Resistance: 1 M or Higher
Check spiral cable.
Repair or replace spiral cable.
Repair or replace harness or connector between
center airbag sensor assembly and spiral cable.
 
 
 
From the results of the above inspection, the malfunctioning part can now be considered normal.
To make sure of this, use the simulation method to check. If the malfunctioning part cannot be
detected by the simulation method, replace all SRS components including the wire harness.
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±59

DTC 12 Short in Squib Circuit (to B+)
CIRCUIT DESCRIPTION
The squib circuit consists of the center airbag sensor assembly, spiral cable, steering wheel pad and front pas-
senger airbag assembly. It causes the SRS to deploy when the SRS deployment conditions are satisfied.
The front airbag sensor detects the deceleration force in a frontal collision and is located in the front fender on
the left and right sides.
For details of the function of each component, see FUNCTION OF COMPONENTS on page RS±4.
Diagnostic trouble code 12 is recorded when a B+ short is detected in the squib circuit or the front airbag sensor
circuit.
 DTC No. Diagnosis 
 
 
 
 
 
12
 
 
 
 
 
 

Short circuit in squib wire harness (to B +).


Squib malfunction.


Short circuit in front airbag sensor + S wire harness (to B +).


Front airbag sensors malfunction.


Spiral cable malfunction.


Center airbag sensor assembly malfunction.
RS±60± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

Preparation.
Disconnect center airbag sensor assembly connec-
tor.
Measure resistance between terminals +SR and
±SR, +SL and ±SL of harness side connector of
center airbag sensor assembly.
Resistance: 755
Ð 855

Repair or replace harness or connector between
center airbag sensor assembly and front airbag
sensor (See page RS±36).
Check front airbag sensor circuit. (Measure resistance between terminals
+SR and ±SR, +SL and ±SL of center airbag sensor assembly connector.)
Check front airbag sensor circuit. (Measure resistance between terminals
+SR or +SL of center airbag sensor assembly connector and body ground.)
(1) Disconnect negative (±) terminal cable from the
battery, and wait at least 90 seconds.
(2) Remove steering wheel pad (See page RS±10).
(3) Disconnect connector of front passenger airbag
assembly (See page RS±20).
Store the steering wheel pad with the front surface
facing upward.
Go to code 15.
(1) Connect negative (±) terminal cable to battery.
(2) Turn ignition switch ON.
Measure voltage between terminals +SR or +SL of
harness side connector of center airbag sensor as-
sembly and body ground.
Voltage: 0 Ð 0.1 V
INSPECTION PROCEDURES [P] Preparation [C] Check
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±61