sensor TOYOTA SUPRA 1997 Service User Guide
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Page 62 of 1807
B02572
TRAC OFF
Indicator Light
TRAC Cut
Switch
N19405
- INTRODUCTIONFOR ALL OF VEHICLES
IN-15
15 Author: Date:
1997 SUPRA (RM502U)
(c) Install the antenna feeder at least 20 cm (7.87 in.) away from the ECU and sensors of the vehicle's
electronics systems. For details about ECU and sensors locations, refer to the section on the applica-
ble component.
(d) Do not wind the antenna feeder together with the other wiring. As much as possible, also avoid running
the antenna feeder parallel with other wire harnesses.
(e) Confirm that the antenna and feeder are correctly adjusted.
(f) Do not install powerful mobile communications system.
4. FOR USING OBDII SCAN TOOL OR TOYOTA HAND-HELD TESTER
Observe the following for safety reasons:
Before using the OBDII scan tool or TOYOTA hand-held tester, the OBDII scan tool's instruction
book or TOYOTA hand-held tester's operator manual should be read thoroughly.
Be sure to route all cables securely when driving with the OBDII scan tool or TOYOTA hand-held
tester connected to the vehicle. (i.e. Keep cables away from feet, pedals, steering wheel and shift
lever.)
Two persons are required when test driving with the OBDII scan tool or TOYOTA hand-held tes-
ter, one person to drive the vehicle and one person to operate the OBDII scan tool or TOYOTA
hand-held tester.
5. FOR VEHICLES EQUIPPED WITH TRACTION CON-
TROL (TRAC) SYSTEM
When using a 2 wheel drum tester such as a speedometer tes-
ter or chassis dynamometer, etc., or jacking up the rear wheels
and driving the wheels, always push in the TRAC cut (ºTRAC
OFFº) switch and turn the TRAC system OFF.
(a) Confirm TRAC system is OFF
(1) Press the TRAC cut (ºTRAC OFFº) switch.
(2) Check that the TRAC OFF indicator light comes on
when the TRAC system is turned off by the TRAC
cut switch.
HINT:
The TRAC OFF indicator light should always operate right after
the engine is restarted.
(3) Begin measurements.
Page 67 of 1807
DIAGNOSTIC TROUBLE CODE CHECK PROCEDURE
Diagnostic Trouble
Code Check (Make a
note of and then clear)Confirmation
of SymptomsDiagnostic Trouble
Code CheckProblem Condition
Diagnostic Trouble
Code DisplayProblem symptoms
existSame diagnostic
trouble code is
displayedProblem is still occurring in the diagnostic
circuit.
Normal code is
displayedThe problem is still occurring in a place
other than in the diagnostic circuit.
(The diagnostic trouble code displayed
first is either for a past problem or it is a
secondary problem.)
No problem
symptoms existThe problem occurred in the diagnostic
circuit in the past.
Normal Code DisplayProblem symptoms
existNormal code is
displayedThe problem is still occurring in a place
other than in the diagnostic circuit.
No problem
symptoms existNormal code is
displayedThe problem occurred in a place other
than in the diagnostic circuit in the past.
IN-20- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
20 Author: Date:
1997 SUPRA (RM502U)
2. SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE CHECK
The diagnostic system in the TOYOTA SUPRA fulfills various functions. The first function is the Diagnostic
Trouble Code Check in which a malfunction in the signal circuits to the ECU is stored in code in the ECU
memory at the time of occurrence, to be output by the technician during troubleshooting. Another function
is the Input Signal Check which checks if the signals from various switches are sent to the ECU correctly.
By using these check functions, the problem areas can be narrowed down quickly and troubleshooting can
be performed effectively. Diagnostic functions are incorporated in the following systems in the TOYOTA SU-
PRA.
SystemDiagnostic Trouble
Code CheckInput Signal Check
(Sensor Check)Other Diagnosis
Function
Engine
Automatic Transmission
Anti-Lock Brake System
ABS & Traction Control System
Supplemental Restraint System
Cruise Control
Air Conditioning (with Check
Mode)
(with Check
Mode)
Diagnostic Test
Mode
Diagnostic Test
Mode
Actuator Check
In diagnostic trouble code check, it is very important to determine whether the problem indicated by the diag-
nostic trouble code is still occurring or occurred in the past but returned to normal at present. In addition,
it must be checked in the problem symptom check whether the malfunction indicated by the diagnostic
trouble code is directly related to the problem symptom or not. For this reason, the diagnostic trouble codes
should be checked before and after the symptom confirmation to determine the current conditions, as shown
in the table below. If this is not done, it may, depending on the case, result in unnecessary troubleshooting
for normally operating systems, thus making it more difficult to locate the problem, or in repairs not pertinent
to the problem. Therefore, always follow the procedure in correct order and perform the diagnostic trouble
code check.
Page 69 of 1807
V07268
VIBRATION METHOD: When vibration seems to be the major cause.
CONNECTORS
WIRE HARNESS
PARTS AND SENSOR1
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint, fulcrum of the vibration, and body
through portion are the major areas to be checked thorough-
ly.
Apply slight vibration with a finger to the part of the sensor
considered to be the problem cause and check if the
malfunction occurs.Shake Slightly
Swing Slightly
Vibrate Slightly
HINT: Applying strong vibration to relays may result in open
relays. IN-22
- INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
22 Author: Date:
1997 SUPRA (RM502U)
3. SYMPTOM SIMULATION
The most difficult case in troubleshooting is when there are no problem symptoms occurring. In such cases,
a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and
environment in which the problem occurred in the customer's vehicle. No matter how much experience a
technician has, or how skilled he may be, if he proceeds to troubleshoot without confirming the problem
symptoms he will tend to overlook something important in the repair operation and make a wrong guess
somewhere, which will only lead to a standstill. For example, for a problem which only occurs when the en-
gine is cold, or for a problem which occurs due to vibration caused by the road during driving, etc., the prob-
lem can never be determined so long as the symptoms are confirmed with the engine hot condition or the
vehicle at a standstill. Since vibration, heat or water penetration (moisture) are likely causes for problems
which are difficult to reproduce, the symptom simulation tests introduced here are effective measures in that
the external causes are applied to the vehicle in a stopped condition.
Important Points in the Symptom Simulation Test:
In the symptom simulation test, the problem symptoms should of course be confirmed, but the problem area
or parts must also be found out. To do this, narrow down the possible problem circuits according to the symp-
toms before starting this test and connect a tester beforehand. After that, carry out the symptom simulation
test, judging whether the circuit being tested is defective or normal and also confirming the problem symp-
toms at the same time. Refer to the matrix chart of problem symptoms for each system to narrow down the
possible causes of the symptom.
Page 71 of 1807
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.
Page 73 of 1807
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.
Page 74 of 1807
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)
Page 75 of 1807
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.
Page 76 of 1807
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.
Page 77 of 1807
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.
Page 78 of 1807
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.