TOYOTA AVENSIS 1999 Supplement

IN–26– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
5. PROBLEM SYMPTOMS TABLE
The suspected circuits or parts for each problem symptom are shown in the table below. Use this table to
troubleshoot the problem when a ”Normal” code is displayed in the diagnostic trouble code check but the
problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts
should be checked.
HINT:
When the problem is not detected by the diagnostic system even though the problem symptom is present,
it is considered that the problem is occurring outside the detection range of the diagnostic system, or that
the problem is occurring in a system other than the diagnostic system.
Symptom
Suspect AreaSee page
With the ignition switch in the ACC or ON position, 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
With the ignition switch in the ACC or ON position, the SRS warning
light does not light up.
PROBLEM SYMPTOMS TABLE
DTC is not displayed.
SRS warning light is always lit up at the time of DTC check
procedure.
DTC is displayed without Tc and E1 terminal connection.DI–294 DI–290
 Problem Symptom
Proceed with troubleshooting of each circuit in the table below.
 SRS warning light circuit
(Always lights up when ignition switch is in
LOCK position.)
 SRS warning light circuit
(Dose not light up when ignition switch is turned to
ACC or ON.)
 Tc terminal circuit
DI–288
Circuit Inspection, Inspection Order
Indicates the circuit which needs to be checked for each problem
symptom. Check in the order indicated by the numbers. Page
Indicates the page where the flow chart for each circuit
is located. 
Circuit or Part Name
Indicates the circuit or part which needs to be checked. 









B02407
WIRING DIAGRAM
DTC 13 Short in D Squib Circuit
CIRCUIT DESCRIPTION
The D squib circuit consists of the airbag sensor assembly, spiral cable and steering wheel pad.
It causes the airbag to deploy when the airbag deployment conditions are satisfied.
For details of the function of each components,see OPERATION on page RS–2.
DTC 13 is recorded when a short is detected in the D squib circuit.
DTC No.DTC Detecting Condition
Trouble Area
Short circuit between D wire harness and D wire harness of squib
D squib malfunction
Spiral cable malfunction
Airbag sensor assembly malfunctionSteering wheel pad (D squib)
Spiral cable
Airbag sensor assembly
Wire harness
 Diagnostic Trouble Code No. and Detection Item
Circuit Description
The major role and operation, etc. of the circuit
and its component parts are explained. 
Indicates the diagnostic trouble code, diagnostic
trouble code set parameter and suspect area of
the problem. 
Wiring Diagram
This shows a wiring diagram of the circuit.
Use this diagram together with ELECTRICAL
WIRING DIAGRAM to thoroughly understand the
circuit.
Wire colors are indicated by an alphabetical code.
B = Black, L = Blue, R = Red, BR = Brown,
LG = Light Green, V = Violet, G = Green,
O = Orange, W = White, GR = Gray, P = Pink,
Y = Yellow
The first letter indicates the basic wire color and
the second letter indicates the color of the stripe. 
Spiral
Cable
G–R
G–Y 1
27
6D+
D–
A15
A15
D SquibAirbag Sensor
Assembly
13
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN–27
6. CIRCUIT INSPECTION
How to read and use each page is shown below.




 

B00972
ONTurn ignition switch ON. INSPECTION PROCEDURE
2 Check voltage at IG2 and ACC of airbag sensor assembly.
OK:
Voltage: Below 16V
Connector being checked is connected.  Indicates the condition of the connector of ECU during the check.PREPARATION:
CHECK:
Check battery and charging system.
(See charging system section)
OKNG
 Indicates the position of the ignition switch during the check.
Check from the connector back side.
(with harness)
Ignition Switch LOCK (OFF)
Ignition Switch START
LOCKIgnition Switch ON
Ignition Switch ACC
STARTON
ACC
Inspection Procedure
Use the inspection procedure to determine
if the circuit is normal or abnormal, and if it
is abnormal, use it to determine whether the
problem is located in the sensors, actuators,
wire harness or ECU.
 Indicates the place to check the voltage or resistance.
 Indicates the connector position to be checked, from the front or back side.
Connector being checked is disconnected. Check from the connector front side. (without harness)
In this case, care must be taken not to bend the terminals.
E6 Connector KNKWire Harness
E6 Connector KNK
Measure voltage between terminals IG2 and ACC of
airbag sensor assembly and body ground.
Airbag Sensor Assembly
(+)
(–)ACC IG2
 IN–28
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS

FI0048
FI0047
FI0046
IN011–03
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN–29
HOW TO USE THE DIAGNOSTIC
CHART AND INSPECTION
PROCEDURE
1. CONNECTOR CONNECTION AND TERMINAL IN-
SPECTION
For troubleshooting, diagnostic trouble code charts or
problem symptom charts are provided for each circuit with
detailed inspection procedures on the following pages.
When all the component parts, wire harnesses and con-
nectors of each circuit except the ECU are found to be
normal in troubleshooting, then it is determined that the
problem is in the ECU. Accordingly, if diagnosis is per-
formed without the problem symptoms occurring, refer to
Step 8 to replace the ECU. So always confirm that the
problem symptoms are occurring, or proceed with inspec-
tion while using the symptom simulation method.
The instructions ”Check wire harness and connector” and
”Check and replace ECU” which appear in the inspection
procedure, are common and applicable to all diagnostic
trouble codes. Follow the procedure outlined below
whenever these instructions appear.
OPEN CIRCUIT:
This could be due to a disconnected wire harness, faulty con-
tact in the connector, and a connector terminal pulled out, etc.
HINT:
It is rarely the case that a wire is broken in the middle of
it. Most cases occur at the connector. In particular, care-
fully check the connectors of sensors and actuators
Faulty contact could be due to rusting of the connector
terminals, to foreign materials entering terminals or a de-
formation of connector terminals. Simply disconnecting
and reconnecting the connectors once changes the
condition of the connection and may result in a return to
normal operation. Therefore, in troubleshooting, if no ab-
normality is found in the wire harness and connector
check, but the problem disappears after the check, then
the cause is considered to be in the wire harness or con-
nectors.
SHORT CIRCUIT:
This could be due to a contact between wire harness and the
body ground or to a short circuit occurred inside the switch, etc.
HINT:
When there is a short between the wire harness and body
ground, check thoroughly whether the wire harness is caught
in the body or is clamped properly.

FI7187
IN0379
Sensor Side
ECU Side
IN0378
Sensor SideECU Side
IN0380
Sensor SideECU Side
IN0381
Pull Lightly
Looseness of Crimping
IN–30– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
2. CONNECTOR HANDLING
When inserting tester probes into a connector, insert them from
the rear of the connector. When necessary, use mini test leads.
For water resistant connectors which cannot be accessed from
behind, take good care not to deform the connector terminals.
3. CONTINUITY CHECK (OPEN CIRCUIT CHECK)
(a) Disconnect the connectors at both ECU and sensor
sides.
(b) Measure the resistance between the applicable terminals
of the connectors.
Resistance: 1 Ω or less
HINT:
Measure the resistance while lightly shaking the wire harness
vertically and horizontally.
4. RESISTANCE CHECK (SHORT CIRCUIT CHECK)
(a) Disconnect the connectors on both ends.
(b) Measure the resistance between the applicable terminals
of the connectors and body ground. Be sure to carry out
this check on the connectors on both ends.
Resistance: 1 MΩ or higher
HINT:
Measure the resistance while lightly shaking the wire harness
vertically and horizontally.
5. VISUAL CHECK AND CONTACT PRESSURE CHECK
(a) Disconnect the connectors at both ends.
(b) Check for rust or foreign material, etc. in the terminals of
the connectors.
(c) Check crimped portions for looseness or damage and
check that the terminals are secured in lock portion.
HINT:
The terminals should not come out when pulled lightly from the
back.

Z17004
Fig. 1
OPENECU
2 Sensor
22 21 111A B C
Z17005
Fig. 2
ECU
Sensor
21A
B C
1
1
22
B04722
Fig. 3
ECU
Sensor
21A B1 C
1
1
221
2 B2
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN–31
(d) Prepare a test male terminal and insert it in the female ter-
minal, then pull it out.
NOTICE:
When testing a gold–plated female terminal, always use a
gold–plated male terminal.
HINT:
When the test terminal is pulled out more easily than others,
there may be poor contact in that section.
6. CHECK OPEN CIRCUIT
For the open circuit in the wire harness in Fig. 1, perform ”(a)
Continuity Check” or ”(b) Voltage Check” to locate the section.
(a) Check the continuity.
(1) Disconnect connectors ”A” and ”C” and measure
the resistance between them.
In the case of Fig. 2,
Between terminal 1 of connector ”A” and terminal 1
of connector ”C” → No continuity (open)
Between terminal 2 of connector ”A” and terminal 2
of connector ”C” → Continuity
Therefore, it is found out that there is an open circuit
between terminal 1 of connector ”A” and terminal 1
of connector ”C”.
(2) Disconnect connector ”B” and measure the resis-
tance between the connectors.
In the case of Fig. 3,
Between terminal 1 of connector ”A” and terminal 1
of connector ”B1” → Continuity
Between terminal 1 of connector ”B2” and terminal
1 of connector ”C” → No continuity (open)
Therefore, it is found out that there is an open circuit
between terminal 1 of connector ”B2” and terminal
1 of connector ”C”.

Z17007
Fig. 4
Sensor
21A
C
1
1
22B5V
5V
5V
0V
Z17008
Fig. 5
2 1A C
1
1
22
BSHORT
Z17009
Fig. 6
21A C
1
1
22
BSensorECU IN–32
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
(b) Check the voltage.
In a circuit in which voltage is applied (to the ECU connector ter-
minal), an open circuit can be checked for by conducting a volt-
age check.
As shown in Fig. 4, with each connector still connected,
measure the voltage between body ground and terminal
1 of connector ”A” at the ECU 5V output terminal, terminal
1 of connector ”B”, and terminal 1 of connector ”C”, in that
order.
If the results are:
5V: Between Terminal 1 of connector ”A” and Body Ground
5V: Between Terminal 1 of connector ”B” and Body Ground
0V: Between Terminal 1 of connector ”C” and Body Ground
Then it is found out that there is an open circuit in the wire har-
ness between terminal 1 of ”B” and terminal 1 of ”C”.
7. CHECK SHORT CIRCUIT
If the wire harness is ground shorted as in Fig. 5, locate the sec-
tion by conducting a ”continuity check with ground”.
Check the continuity with ground.
(1) Disconnect connectors ”A” and ”C” and measure
the resistance between terminal 1 and 2 of connec-
tor ”A” and body ground.
In the case of Fig. 6
Between terminal 1 of connector ”A” and body
ground → Continuity (short)
Between terminal 2 of connector ”A” and body
ground → No continuity
Therefore, it is found out that there is a short circuit
between terminal 1 of connector ”A” and terminal 1
of connector ”C”.

Z17808
Fig. 7
Sensor
21A B1 C
1
1
221
2 B2
ECU
IN0383
Example
Ground
IN0384
Ground
Ground
ECU Side
W/H Side
– INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN–33
(2) Disconnect connector ”B” and measure the resis-
tance between terminal 1 of connector ”A” and body
ground, and terminal 1 of connector ”B2” and body
ground.
Between terminal 1 of connector ”A” and body
ground → No continuity
Between terminal 1 of connector ”B2” and body
ground → Continuity (short)
Therefore, it is found out that there is a short circuit
between terminal 1 of connector ”B2” and terminal
1 of connector ”C”.
8. CHECK AND REPLACE ECU
First check the ECU ground circuit. If it is faulty, repair it. If it is
normal, the ECU could be faulty, so replace the ECU with a nor-
mal functioning one and check that the symptoms appear.
(1) Measure the resistance between the ECU ground
terminal and the body ground.
Resistance: 1 Ω or less
(2) Disconnect the ECU connector, check the ground
terminals on the ECU side and the wire harness
side for bend and check the contact pressure.

IN044–07
IN–34
– INTRODUCTIONTERMS
TERMS
ABBREVIATIONS USED IN THIS MANUAL
AbbreviationsMeaning
ABSAnti–Lock Brake System
A/CAir Conditioner
ACAlternating Current
ACCAccessory
ACISAcoustic Control Induction System
ACSDAutomatic Cold Start Device
A.D.D.Automatic Disconnecting Differential
AHCActive Height Control Suspension
ALRAutomatic Locking Retractor
ALTAlternator
AMPAmplifier
ANTAntenna
APPROX.Approximately
A/TAutomatic Transmission (Transaxle)
AT FAutomatic Transmission Fluid
AUTOAutomatic
BACSBoost Altitude Compensation System
BATBattery
B/LBi–Level
BVSVBimetallic Vacuum Switching Valve
CBCircuit Breaker
CDCompact Disc
CHChannel
CKDComplete Knock Down
COMB.Combination
CPECoupe
CRSChild Restraint System
CTRCenter
DCDirect Current
DIFF.Differential
DIFF. LOCKDifferential Lock
DLCData Link Connector
DSPDigital Signal Processor
DTCDiagnostic Trouble Code
ECTElectronic Control Transmission
ECUElectronic Control Unit
EDUElectronic Driving Unit
EFIElectronic Fuel Injection
E/GEngine
EGRExhaust Gas Recirculation
ELREmergency Locking Retractor
E–VRVElectronic Vacuum Regulating Valve

– INTRODUCTIONTERMS
IN–35
FFFront–Engine Front–Wheel–Drive
FIPGFormed In Place Gasket
FLFusible Link
FrFront
FRFront–Engine Rear–Wheel–Drive
FWDFront–Wheel–Drive
GNDGround
H/BHatchback
HIHigh
HIDHigh Intensity Discharge (Head Lamp)
HTHard Top
HWSHeated Windshield System
IACIdle Air Control
IFSIndependent Front Suspension
IGIgnition
INTIntermittent
I/PInstrument Panel
IRSIndependent Rear Suspension
J/BJunction Block
J/CJunction Connector
LANLocal Area Network
LBLiftback
LCDLiquid Crystal Display
LEDLight Emitting Diode
LHLeft–Hand
LHDLeft–Hand Drive
LOLow
LSDLimited Slip Differential
LSP & PVLoad Sensing Proportioning And Bypass Valve
LSPVLoad Sensing Proportioning Valve
MAPManifold Absolute Pressure
MAX.Maximum
MICMicrophone
MILMalfunction Indicator Lamp
MIN.Minimum
MPMultipurpose
MPIMultipoint Electronic Fuel Injection
MPXMultiplex Communication System
M/TManual Transmission
NNeutral
No.Number
O2SOxygen Sensor
O/DOverdrive
OPTOption
P & BVProportioning And Bypass Valve
PCSPower Control System