TOYOTA SUPRA 1997 Service Manual PDF

DTC No.
Indicates the diagnostic trouble code.

Page or Instructions
Indicates the page where the inspection procedure
for each circuit is to be found, or gives instructions
for checking and repairs.

Detection Item
Indicates the system of the problem or
contents of the problem.
Trouble Area
Indicates the suspect area of the
problem.
Mass Air Flow Circuit MalfunctionDetection Item

Open or short in mass air flow meter circuit

Mass air flow meter

ECM DTC No.
(See page)Trouble AreaMIL*MemoryP0100
(DI-23)
P0101
(DI-27)Mass Air Flow Circuit
Range/Performance Problem
Mass air flow meter
P0115
(DI-32)
Open or short in intake air temp. sensor circuit

Intake air temp. sensor

ECM Intake Air Temp. Circuit Malfunction P0110
(DI-28)
Engine Coolant Temp. Circuit
Range/Performance Problem
Open or short in engine coolant temp. sensor circuit

Engine coolant temp. sensor

ECM
P0120
(DI-37)
Throttle/ Pedal Position Sensor/Switch
ºAº Circuit Range/Performance
P0116
(DI-36)
Throttle/Pedal Position Sensor/Switch
ºAº Circuit Malfunction
Insufficient Coolant Temp. for Closed
Engine coolant temp. sensor

Cooling system Engine Coolant Temp. Circuit
Malfunction

Open or short in throttle position sensor circuit

Throttle position sensor

ECM

Throttle position sensor

Open or short in heated oxygen sensor circuit

Heated oxygen sensor
DTC CHART (SAE Controlled)
HINT: Parameters listed in the chart may not be exactly the same as your reading due to the type of instrument
or other factors.
If a malfunction code is displayed during the DTC check mode, check the circuit for that code listed in the table
below. For details of each code, turn to the page referred to under the ºSee pageº for the respective ºDTC No.º
in the DTC chart.
IN-24- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
24 Author
: Date
:
1997 SUPRA (RM502U)
4. DIAGNOSTIC TROUBLE CODE CHART
The inspection procedure is shown in the table below. This table permits efficient and accurate troubleshoot-
ing using the diagnostic trouble codes displayed in the diagnostic trouble code check. Proceed with trouble-
shooting in accordance with the inspection procedure given in the diagnostic chart corresponding to the
diagnostic trouble codes displayed. The engine diagnostic trouble code chart is shown below as an example.

- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN-25
25 Author
: Date
:
1997 SUPRA (RM502U)
5. PROBLEM SYMPTOMS TABLE
The suspect circuits or parts for each problem symptom are shown in the table below. Use this table to trou-
bleshooting the problem when a ºNormalº 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
Engine does not crank (Does not start)
No initial combustion (Does not start)
No complete combustion (Does not start)1. Starter and starter relay
1. ECM power source circuit
2. Fuel pump control circuit
3. Engine control module (ECM)
1. Starter signal circuit
2. Fuel pump control circuit1. Fuel pump control circuit
PROBLEM SYMPTOMS TABLE
1. Compression
2. Fuel pump control circuit 1. A/C signal circuit
2. Fuel pump control circuit 1. A/C signal circuit (Compressor circuit)
2. ECM power source circuit 1. Starter signal circuit
2. Fuel pump control circuit1. Starter signal circuit
2. Fuel pump control circuit
3. Compression
idling) Hot engine Cold engine (Difficult to start)Engine cranks normally (Difficult to start)

Problem Symptom
Page
Indicates the page where the flow chart for each circuit
is located.

Circuit Inspection, Inspection Order
Indicates the circuit which needs to be checked for each problem
symptom. Check in the order indicated by the numbers.

Circuit or Part Name
Indicates the circuit or part which needs to be checked.
ST-14,ST-15
DI-144
DI-148
SF-67
DI-141
EM-3
DI-825 DI-148
DI-148
DI-148
DI-148 DI-141
DI-141

V08423 Knock Sensor 1
GRECM
KNK
E1 12
E6
WIRING DIAGRAM
DTC P0325Knock Sensor 1 Circuit Malfunction
CIRCUIT DESCRIPTION
Knock sensor is fitted to the cylinder block to detect engine knocking. This sensor contains a piezoelectric element which
generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to knocking. If engine
knocking occurs, ignition timing is retarded to suppress it.
DTC No. DTC Detecting Condition Trouble Area
P0325No knock sensor 1 signal to ECM with engine speed,
1,200 rpm or more.
Open or short in knock sensor1 circuit

Knock sensor 1 (looseness)

ECM
If the ECM detects the above diagnosis conditions, it operates the fall safe function in which the corrective retard angle
value is set to the maximum value.

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 wring diagram of the circuit.
Use the diagram together with ELECTRICAL
WIRING DIAGRAM to thoroughly understand the
circuit.
Wiring 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. IN-26
- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
26 Author
: Date
:
1997 SUPRA (RM502U)
6. CIRCUIT INSPECTION
How to read and use each page is shown below.

V08425
LOCK
KNK
E6 Connector
(a) Remove the glove compartment.
(b) Disconnect the E6 connector of ECM.
INSPECTION PROCEDURE
Replace knock sensor. 1 Check continuity between terminal KNK of ECM connector and body ground.
OK:
Check knock sensor (See page SF-67).Measure resistance between terminal KNK of ECM connector
and body ground.
Resistance: 1 MW or higher
Connector being checked is connected.
Indicates the condition of the connector of ECU during the check.
PREPARATION:
CHECK:
2Go to step 3.
OK OK
NG

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

Indicates the place to check the voltage or resistance.

Indicates the connector position to 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
A00255 AB0117
A00265

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.
- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN-27
27 Author
: Date
:
1997 SUPRA (RM502U)

IN04H-01
FI0046
FI0047
FI0048
IN-28- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
28 Author
: Date
:
1997 SUPRA (RM502U)
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, even if the problem is not in the
ECU. So always confirm that the problem symptoms are
occurring, or proceed with inspection while using the
symptom simulation method.

The instructions ºCheck wire harness and connectorº and
ºCheck and replace ECUº 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, 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 drop
in the contact pressure between the male and female ter-
minals of the connector. Simply disconnecting and recon-
necting the connectors once changes the condition of the
connection and may result in a return to normal operation.
Therefore, in troubleshooting, if no abnormality 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 connectors.
SHORT CIRCUIT:
This could be due to a short circuit between the wire harness
and the body ground or to a short 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.

B01402
Sensor Side
ECU Side
IN0378
Sensor SideECU Side
IN0380
Sensor SideECU Side
IN0381
Pull Lightly
Looseness of Crimping
- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN-29
29 Author
: Date
:
1997 SUPRA (RM502U)
2. 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 W or less
HINT:

Measure the resistance while lightly shaking the wire har-
ness vertically and horizontally.

When tester probes are inserted into a connector, insert
the probes from the back. For waterproof connectors in
which the probes cannot be inserted from the back, be
careful not to bend the terminals when inserting the tester
probes.
3. RESISTANCE CHECK (SHORT CIRCUIT CHECK)
(a) Disconnect the connectors at 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 MW or higher
HINT:
Measure the resistance while lightly shaking the wire harness
vertically and horizontally.
4. 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 if the terminals are secured in lock portion.
HINT:
The terminals should not come out when pulled lightly.
(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.

FI7187
B01403
Fig.1
SensorECU
OPEN
B
C
1 1 1 1
2 2
2 2A
B01405
Fig.2
Sensor
1 1 1
22 2 C
BA
ECU
B04722
Fig. 3
ECU
Sensor
21A B1 C
1
1
221
2 B2
IN-30- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
30 Author
: Date
:
1997 SUPRA (RM502U)
5. 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.
6. CHECK OPEN CIRCUIT
For the open circuit in the wire harness in Fig.1, perform º(a)
Continuity Checkº or º(b) Voltage Checkº to locate the section.
(a) Check the continuity.
(1) Disconnect connectors ºAº and ºCº and measure
the resistance between them.
In the case of Fig.2,
Between terminal 1 of connector ºAº and terminal 1
of connector ºCº " No continuity (open)
Between terminal 2 of connector ºAº and terminal 2
of connector ºCº " Continuity
Therefore, it is found out that there is an open circuit
between terminal 1 of connector ºAº and terminal 1
of connector ºCº.
(2) Disconnect connector ºBº and measure the resis-
tance between the connectors.
In the case of Fig.3,
Between terminal 1 of connector ºAº and terminal 1
of connector ºB1º " Continuity
Between terminal 1 of connector ºB2º and terminal
1 of connector ºCº " No continuity (open)
Therefore, it is found out that there is an open circuit
between terminal 1 of connector ºB2º and terminal
1 of connector ºCº.

B01407
Fig.4
SensorECU
1 1 1
2 2
2 C
BA
5V
5V 0V
B01408
Fig.5
SHORT C
1 1
2 2 B A
2 1
B01409
Fig.6
Sensor
1 1
1
2B
AECU
C
2 2
- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN-31
31 Author
: Date
:
1997 SUPRA (RM502U)
(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.
(1) As shown in Fig.4, with each connector still con-
nected, measure the voltage between body ground
and terminal 1 of connector ºAº at the ECU 5V out-
put terminal, terminal 1 of connector ºBº, and termi-
nal 1 of connector ºCº, in that order.
If the results are:
5V: Between Terminal 1 of connector ºAº and Body
Ground
5V: Between Terminal 1 of connector ºBº and Body
Ground
0V: Between Terminal 1 of connector ºCº and Body
Ground
Then it is found out that there is an open circuit in
the wire harness between terminal 1 of ºBº and ter-
minal 1 of ºCº.
7. CHECK SHORT CIRCUIT
If the wire harness is ground shorted as in Fig.5, locate the sec-
tion by conducting a ºcontinuity check with ground º.
(a) Check the continuity with ground.
(1) Disconnect connectors ºAº and ºCº and measure
the resistance between terminal 1 and 2 of connec-
tor ºAº and body ground.
In the case of Fig.6,
Between terminal 1 of connector ºAº and body
ground " Continuity (short)
Between terminal 2 of connector ºAº and body
ground " No continuity
Therefore, it is found out that there is a short circuit
between terminal 1 of connector ºAº and terminal 1
of connector ºCº.

B01411
Fig.7
SensorECU
1 1
2 2B1 A C B2
1 1
2 2
IN0383
Example
Ground
IN0384
ECU Side
Ground
W/H Side
Ground
IN-32- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
32 Author
: Date
:
1997 SUPRA (RM502U)
(2) Disconnect connector ºBº and measure the resis-
tance between terminal 1 of connector ºAº and body
ground, and terminal 1 of connector ºB2º and body
ground.
Between terminal 1 of connector ºAº and body
ground " No continuity
Between terminal 1 of connector ºB2º and body
ground " Continuity (short)
Therefore, it is found out that there is a short circuit
between terminal 1 of connector ºB2º and terminal
1 of connector ºCº.
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
known good one and check if the symptoms appear.
(a) Measure the resistance between the ECU ground termi-
nal and the body ground.
Resistance: 1 W or less
(b) Disconnect the ECU connector, check the ground termi-
nals on the ECU side and the wire harness side for bend
and check the contact pressure.

IN04I-01
- INTRODUCTIONTERMS
IN-33
33 Author
: Date
:
1997 SUPRA (RM502U)
TERMS
ABBREVIATIONS USED IN THIS MANUAL
AbbreviationsMeaning
ABSAnti-Lock Brake System
ALRAutomatic Locking Retractor
APPROX.Approximately
A/T, ATMAutomatic Transmission
AT FAutomatic Transmission Fluid
BTDCBefore Top Dead Center
CBCircuit Breaker
CDCompact Disc
CRSChild Restraint System
DOHCDouble Over Head Cam
DPDash Pot
ECUElectronic Control Unit
ELREmergency Locking Retractor
ESAElectronic Spark Advance
EXExhaust (Manifold, Valve)
FIPGFormed in Place Gasket
FLFusible Link
FrFront
H-FuseHigh Current Fuse
IGIgnition
INIntake (Manifold, Valve)
J/BJunction Block
LEDLight Emitting Diode
LHLeft-Hand
LLCLong Life Coolant (Year Around Coolant)
LSDLimited Slip Differential
Max.Maximum
Min.Minimum
MPMultipurpose
M/TManual Transmission
O/D, ODOverdrive
O/SOversize
P&BVProportioning and Bypass Valve
PCVPositive Crankcase Ventilation
PPSProgressive Power Steering
PSPower Steering
RHRight-Hand
RrRear
SRSSupplemental Restraint System
SSMSpecial Service Materials
SSTSpecial Service Tools
STDStandard