TOYOTA SUPRA 1986 Service Owners Manual

INSPECTION PROCEDURE
HINT:
wIf diagnostic trouble code 41 is displayed, check throttle position sensor circuit. If diagnostic trouble code
47 is displayed, check sub±throttle position sensor circuit.
wIf diagnostic trouble code º22º (engine coolant temperature sensor circuit), º24º (intake air temperature
sensor circuit) and º41º (throttle position sensor circuit) are output simultaneously. E2 (sensor ground) may
be open.
(See page EG±505)
(See page EG±510)
(See page EG±292)
Check voltage between terminals VTA1, 2, IDL1, 2 and E2 of engine control
module connector.
The voltage should increase steadily in proportion
to the throttle valve opening angle.
(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Turn ignition switch ON.
(3) For throttle position sensor, disconnect the vacuum
hose from the throttle body, then apply vacuum to
the throttle opener.
(See page EG±292)
(4) For sub±throttle position sensor, remove intake air
duct and disconnect sub±throttle valve step motor
connector.
Measure voltage between terminals VTA1, 2, IDL1,
2 and E2 of engine control module connector when
the (sub±) throttle valve is opened gradually from
the closed condition.
Check for intermittent problems.
(See page
EG±505)
Throttle Valve
Terminal
Fully Closed
Fully Open
EG±554± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(1) Remove throttle body. (See page EG±291)
(2) For throttle position sensor, apply vacuum to
throttle opener. (See page
EG±292)
Measure resistance of each terminal as below table
when the throttle valve is opened gradually from the
closed condition.
Check throttle position sensor(s).
Check for open and short in harness and connector between engine control
module and throttle position sensors(s) (See page
IN±30).
Resistance between terminals 2,3 (VTA1,2) and 4,1
(E2) should increase gradually in accordance with
the throttle valve opening angle.
Adjust or replace throttle position sensor(s).
(See page EG±292)
Repair or replace harness or connector.
Check and replace engine control module.
For Throttle Position Sensor
For Sub±Throttle Position Sensor
Throttle Valve
Terminal
Throttle
Position
Sensor
Sub throttle
Position
Sensor
Fully
Closed Fully
Opened
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±555

DTC 42 No. 1 Vehicle Speed Sensor Signal Circuit
CIRCUIT DESCRIPTION
The No.1 vehicle speed sensor outputs a 4±pulse signal for every revolution of the rotor shaft, which
is rotated by the transmission output shaft via the driven gear. After this signal is converted into a more
precise rectangular waveform by the waveform shaping circuit inside the odometer and trip meter, it is
then transmitted to the engine control module. The ECM determines the vehicle speed based on the
frequency of these pulse signals.
DTC No.Diagnostic Trouble Code Detecting ConditionTrouble Area
For A/T
All conditions below are detected
Continuously for 8 sec. or more:
(a) No.1 vehicle speed signal: 0 km/h
(mph)
(b) Engine speed: 3,000 rpm or more
(c) Park/neutral position switch: OFF
(d) Stop light switch: OFF
For A/T
All conditions below are detected
Continuously for 8 sec. or more:
(a) No.1 vehicle speed signal: 0 km/h
(mph)
(b) Engine speed: Between 1,500 rpm
and 4,000 rpm
(c) Engine coolant temp.: 80°C (176°F)
or more
(d) Load driving

No.1 vehicle speed sensor

Telltale light RH (Odometer and trip meter)

Open or short in No.1 vehicle speed sensor
circuit

ECM
HINT: In test mode, diagnostic trouble code 42 is output when vehicle speed is 5 km/h (3 mph) or
below.

Waveform between terminals SP1 and E1 when vehicle
speed is approx. 20 km/h (12mph).
HINT: As the vehicle speed increases, the number of signals
from SP1 increases. EG±556
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±557

INSPECTION PROCEDURE
(See page EG±510)
(1) Shift the shift lever to N position.
(2) Jack up one of the rear wheels.
(3) Connect SST (check harness ªAº).
(See page
EG±510)
(4) Disconnect power steering ECU connector
and cruise control ECU connector.
(5) Turn ignition switch ON.
Measure voltage between terminal SP1 of engine
control module connector and body ground when
the wheel is turned slowly.
Voltage is generated intermittently.
Check voltage between terminal SP1 of engine control module connector
and body ground.
Check and replace engine control module.
Repair or replace harness or connector between
ECM and telltale light RH.
Repair or replace harness or connector between
telltale light RH and No.1 vehicle speed sensor.
Replace No.1 vehicle speed sensor.
Check operation of odometer and trip meter (telltale light RH
(See page Be±48)).
Check operation of No.1 vehicle speed sensor (See page BE±46).
EG±558± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

DTC 43 Starter Signal Circuit
CIRCUIT DESCRIPTION
When the engine is being cranked, the intake air flow is slow, so fuel vaporization is poor. A rich mixture is there-
fore necessary in order to achieve good startability. While the engine is being cranked, the battery positive volt-
age is applied to terminal STA of the ECM. The starter signal is mainly used to increase the fuel injection volume
for the starting injection control and after±start injection control.
 
 DTC No.
 
 Diagnostic Trouble Code Detecting Condition
 
 Trouble Area
 
 
 
 
43
 
 
 
 
No starter signal to ECM
 
 
 
 

Open or short in starter signal circuit

Open or short in ignition switch or starter
relay circuit

ECM
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±559

INSPECTION PROCEDURE
HINT: This diagnostic chart is based on the premise that the engine is being cranked under normal conditions.
If the engine does not crank, proceed to the matrix chart of problem symptoms on page EG±514.
(See page EG±514).
Setting the test mode.
(1) Turn ignition switch OFF.
(2) Connect terminals TE2 and E1 of DLC2.
(3) Turn ignition switch ON.
(Don't start the engine)
(4) Connect terminal TE1 and E1 of DLC2.
Check if code ª43º is output by the malfunction indi-
cator lamp.
Code ª43º is output.
Start the engine.
Check if code ª43º disappears.
Code ª43º is not output.
Check output condition of diagnostic trouble code 43.
Proceed to next circuit inspection shown on
matrix chart (See page Eg±514.)
Check and replace engine control module.
Check for open in harness and connector between engine control module
and starter relay (See page IN±30).
Repair or replace harness or connector.
EG±560± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

DTC 52 53 55 Knock Sensor Circuit
CIRCUIT DESCRIPTION
Knock sensors are fitted one each to the front and rear of the left side of the cylinder block to detect
engine knocking. This sensor contains a piezoelectric element which generates a voltage when it be-
comes deformed, which occurs when the cylinder block vibrates due to knocking. If engine knocking
occurs, ignition timing is retarding to suppress it.
DTC No.Diagnostic Trouble Code Detecting ConditionTrouble Area
No No.1 knock sensor signal to ECM for 4
crank revolutions with engine speed between
2,050 rpm and 5,950 rpm
Engine control computer (for knock control)
malfunction at engine speed between 650 rpm
and 5,200 rpm
No No.2 knock sensor signal to ECM for 4
crank revolutions with engine speed between
2,050 rpm and 5,950 rpm

Open or short in No.1 knock sensor circuit

No.1 knock sensor (Looseness)

ECM

ECM

Open or short No.2 knock sensor circuit

No.2 knock sensor (looseness)

ECM
If the ECM detects the above diagnosis conditions, it operates the fail safe function in which the cor-
rective retard angle value is set to the maximum value.
Purpose of the driving pattern.
(a) To simulate diagnostic trouble code detecting condition after diagnostic trouble code is recorded.
(b) To check that the malfunction is corrected when the repair is completed by confirming that diagnos±
tic trouble code is no longer detected.
DIAGNOSTIC TROUBLE CODE DETECTION DRIVING PATTERN
Malfunction: Open or short in Knock Sensor
(1) Start the engine and warm up.
(2) Idle the engine for 3 min.
(3) With the A/C ON, race the engine quickly to 5,000 rpm 3 times.
(Rapidly depress the accelerator pedal and suddenly release it.)
HINT: If a malfunction exists, the malfunction indicator lamp will light up when sudden racing is
performed.
NOTICE: If the conditions in this test are not strictly followed, detection of the malfunction
will not be possible.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±561

INSPECTION PROCEDURE
HINT: If diagnostic trouble code 52 is displayed, check No.1 knock sensor (for front side) circuit.
If diagnostic trouble code 55 is displayed, check No.2 knock sensor (for rear side) circuit.
If diagnostic trouble code 53 is displayed, replace engine control module.
(See page EG±510)
(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Disconnect the engine control module con±
nectors.
Measure resistance between terminals KNK1,
KNK2 of engine control module connector and
body ground.
Resistance: 1 M
or higher
Check continuity between terminals KNK1, KNK2 of engine control module
connector and body ground.
EG±562± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

With the engine racing (4,000 rpm) measure
waveform between terminals KNK1, KNK2 of
engine cotrol module and body ground.
HINT: The correct waveform is as shown.

Spread the time on the horizontal axis, and con
firm that the period of the wave is 123
sec.
(Normal mode vibration frequency of knock
sensor: 8.1 KHz).
HINT: If normal mode vibration frequency is not 8.1 KHz,
the sensor is malfunctioning.
(See page EG±316)
(See page IN±30.)
(See page EG±316)
Disconnect knock sensor connector.
Measure resistance between the knock sensor terminal
and body.
Resistance: 1 M
or higher
Check knock sensor.
Replace knock sensor (See page EG±316)
Check for open and short in harness and connector between engine control
module and knock sensor (See page IN±30).
Repair or replace harness or connector.
Does malfunction disappear when a good knock sensor is installed?
Replace knock sensor. (See page EG±316)
Check and replace engine control module.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±563