sensor TOYOTA SUPRA 1995 Service Repair Manual

DTC 31 Center Airbag Sensor Assembly Malfunction
CIRCUIT DESCRIPTION
The center airbag sensor assembly consists of a center airbag sensor, safing sensor, drive circuit, diagnosis
circuit and ignition control, etc.
It receives signals from the airbag sensors, judges whether or not the SRS must be deployed, and diagnostic
system malfunction.
Diagnostic trouble code 31 is recorded when a occurrence of a malfunction in the center airbag sensor assembly
is detected.
 DTC No. Diagnosis 
 31
 
 
Center airbag sensor assembly malfunction.
INSPECTION PROCEDURES
HINT: When a malfunction code other than code 31 is displayed at the same time, first repair the malfunction
indicated by the malfunction code other than code 31.
[P] Preparation [C] Check
Is diagnostic trouble code 31 output again?
Clear malfunction code (See page RS±47).
(1) Turn ignition switch to LOCK, and wait at least
20 seconds.
(2) Turn ignition switch to ACC or ON, and wait at
least 20 seconds.
(3) Repeat step (1) and (2) at least 5 times.
(4) Using SST, connect terminals TC and E
1 of DL C1
or DLC2.
SST 09843±18020
(7) Check diagnostic trouble code.
Replace center airbag sensor assembly.
Using simulation method, reproduce mal-
function symptoms (See page RS±48). RS±86
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

DTC 53 Short in P Squib Circuit (Between P+ Wire Harness and P±
Wire Harness)
CIRCUIT DESCRIPTION
The P squib circuit consists of the center airbag sensor assembly and front passenger airbag assembly. It
causes the airbag to deploy when the airbag deployment conditions are satisfied.
For details of the function of each component see FUNCTION OF COMPONENTS on page RS±4. Diagnostic
trouble code 53 is recorded when a short is detected in the P
+ wire harness and P± wire harness of the squib
circuit.
 DTC No. Diagnosis
 
 
 53
 
 
 

Short circuit between P+ wire harness P± wire harness of squib.


P squib malfunction.


Center airbag sensor assembly malfunction.
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±87

Preparation.
Check P squib circuit.
(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).
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
+ and P±.
Resistance: 1 k
or higher
Store the steering wheel pad with the front sur-
face facing upward.
INSPECTION PROCEDURES [P] Preparation [C] Check
RS±88± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

Check center airbag sensor assembly.
(1) Turn ignition switch to LOCK, and wait at least
2 seconds.
(2) Turn ignition switch to ACC or ON, wait at least
20 seconds.
(3) Clear malfunction code stored in memory. (See
page RS±47)
(4) Turn ignition switch to LOCK, and wait at least
20 seconds.
(5) Remove the service wire which connect P
+ and
P± on center airbag assembly side of connector
between center airbag sensor assembly and
front passenger airbag assembly.
(6) Using SST, connect terminals Tc and E
1 of DLC1
or DLC2.
SST 09843±18020
(7) Check diagnostic trouble code.
Diagnostic trouble code 53 is not output.
Codes other than code 53 may be output at this
time, but they are not relevant to this check.
Replace center airbag sensor assembly.
(1) Using a service wire, connect D+
and D± on spi±
ral cable side of connector between spiral cable
and steering wheel pad.
(2) Using a service wire, connect P
+ and P± on center
airbag sensor assembly side of connector be±
tween center airbag sensor assembly and front
passenger airbag assembly.
(3) Connect negative (±) terminal cable to battery, and
wait at least 2 seconds.
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±89

Replace center airbag sensor assembly.
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.
Check P squib circuit.
(1) Disconnect center airbag sensor assembly
connector.
(2) Release airbag activation prevention mechanism
on center airbag sensor assembly connector.
(See page RS±72)
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
+ and P±.
Resistance: 1 k
or higher
Check center airbag sensor assembly.
Repair or replace harness or connector be-
tween center airbag sensor assembly and
front passenger airbag assembly.
Connect center airbag sensor assembly connector.
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
+ and P±.
Resistance: 1 k
or higher
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±91

DTC 54 Open in P Squib Circuit
CIRCUIT DESCRIPTION
The P squib circuit consists of the center airbag sensor assembly and front passenger airbag assembly. It
causes the airbag to deploy when the airbag deployment conditions are satisfied.
For details of the function of each component see FUNCTION OF COMPONENTS on page RS±4. Diagnostic
trouble code 54 is recorded when an open is detected in the P squib circuit.
 
 DTC No.
 
 Diagnosis
 
 
 
54
 
 
 

Open circuit in P+ wire harness P± wire harness of squib.


P squib malfunction.


Center airbag sensor assembly malfunction.
RS±92± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

INSPECTION PROCEDURES [P] Preparation [C] Check
Preparation.
(1) Disconnect negative (±) terminal cable from the
battery, and wait at least 90 seconds.
(2) Remove steering wheel pad. (See RS±10)
(3) Disconnect connector of front passenger airbag
assembly. (See page Rs±20)
Repair or replace harness or connector be-
tween center airbag sensor assembly and
front passenger airbag assembly.
Store the steering wheel pad with the front sur-
face facing upward.
Disconnect center airbag sensor assembly connec-
tor.
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
+ and P±.
Resistance: Less than 1

Check P squib circuit.
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±93

Check center airbag sensor assembly.
(1) Turn ignition switch to ACC or ON, and wait at
least 2 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 54 is not output.
Codes other than code 54 may be output at this
time, but they are not relevant to this check.
Replace center airbag sensor assembly.
(1) Connect connector to center airbag sensor
assembly.
(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 center
airbag sensor assembly side of connector be±
tween center airbag sensor assembly and front
passenger airbag assembly.
(4) Connect negative (±) terminal cable to battery, and
wait at least 2 seconds. RS±94
± 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

Tc Terminal Circuit
CIRCUIT DESCRIPTION
By connecting terminals Tc and E1 of the DLC1 or DLC2, the center airbag sensor assembly is set in the diagnos-
tic trouble code output mode. The diagnostic trouble codes are displayed by the blinking of the SRS warning
light.
RS±98± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING