TOYOTA SUPRA 1995 Service Repair Manual

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

When the problem seems to occur when the suspect
area is heated.HEAT METHOD:
Heat the component that is likely the cause of the mal-
function with a hair dryer or similar object. Check to see
if the malfunction will occur.
NOTICE:

Do not heat to more than 60°C (140°F) (Tempera±
ture limit that the component can be touched with
a hand.).

Do not apply heat directly to any part in the ECU.
WATER SPRINKLING
METHOD:When the malfunction seems to occur on a rainy day
or in a high±humidity condition.
Sprinkle water onto the vehicle and check to see if the
malfunction will occur.
NOTICE: Never apply water directly onto the elec-
tronic components.
HINT:

If the vehicle leaks water, the water may contaminate
the ECU. When testing a vehicle with a water leakage
problem, special caution must be paid.
OTHER:When the malfunction seems to occur when electrical load
is excessive.
Turn on all electrical loads including the heater blower,
headlights, rear window defogger, etc. and check to see
if the malfunction will occur.
± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTINGRS±49

DIAGNOSTIC TROUBLE CODE MATRIX CHART
If a malfunction code is displayed during the diagnostic trouble code check, check the circuit listed for that code
in the table below (Proceed to the page given for that circuit.).
 
 DTC No. 
 Diagnosis 
 Page
 (Normal)*1 
Source voltage drop RS±52
 
 
 
11
 
 
 

Short in squib circuit or front airbag sensor circuit (to ground)


Front airbag sensor or center airbag sensor assembly malfunction
 
 
 
RS±54
 
 
 
12 
 
 

Short in squib circuit (to B+)


Open in front airbag sensor circuits
 
 
 
RS±60
 13 
Short in D squib circuit (between D+ wire harness and D± wire harness) RS±66
 
 14
 
 
Open in D squib circuit
 
 RS±73
 
 15
 
 
Open in front airbag sensor circuit
 
 RS±78
 
 22*2 
 
SRS warning light system malfunction 
 RS±82
 31 
Center airbag sensor assembly malfunction RS±86
 
 53
 
 
Short in P squib circuit
 
 RS±87
 
 54
 
 
Open in P squib circuit
 
 RS±92
HINT:
*1 When the SRS warning light remains lit up and the diagnostic trouble code is the normal code, this means
a source voltage drop.
*
2 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.
PROBLEM SYMPTOM CHART
Proceed with troubleshooting of each circuit in the table below.
RS±96
RS±98
Problem SymptomInspection ItemPage

Tc terminal circuit

SRS warning light system
Always lit up, when ignition
switch is in LOCK position.

With the ignition switch at ACC or ON, the SRS warning light
sometimes lights up after approx. 6 seconds have elapsed.

SRS warning light is always lit up even when ignition switch
is in the LOCK position.

Diagnostic trouble code not displayed.

SRS warning light is always lit up with the DTC check procedure.

Diagnostic trouble code displayed without Tc and E1 terminal
correction.
RS±50± SUPPLEMENTAL RESTRAINT SYSTEMTROUBLESHOOTING

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