1986 TOYOTA SUPRA Service Repair Manual

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

See page EG±503.
CIRCUIT DESCRIPTION
The EGR system is designed to recirculate the exhaust gas, controlled according to the driving condi-
tions back into the intake air±fuel mixture. It helps to slow down combustion in the cylinder and thus
lower the combustion temperature which, in turn, reduces the amount of NO
x emission. The amount
of EGR is regulated by the EGR vacuum modulator according to the engine load.
If even one of the following conditions is fulfilled,
the VSV is turned ON by a signal from the ECM.
This resists in atmospheric air acting on the EGR
valve, closing the EGR valve and shutting off the
exhaust gas (EGR cut±OFF).

Engine coolant temp. below 50°C (122°F)

During deceleration (throttle valve closed)

Light engine load (amount of intake air very
small)

Engine speed over 4,800 rpm

Manifold absolute pressure more than 120 kPa
(1.2 kgf/cm
2, 17.4 psi)
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

Open EGR gas temp. sensor circuit

Short in VSV circuit for EGR

EGR hose disconnected, valve stuck

Clogged EGR gas passage

ECM
EGR gas temp. and intake air temp. are
60°C(140°F) or less for A/T, 55°C (131°F) or
less for M/T for 1 ~ 4 min. under conditions (a)
and (b):
(2 trip detection logic)*
(a) Engine coolant temp.: 60°C (140°F) or
more
(b) EGR operation possible (Example A/T in
3rd speed (5th for M/T), A/C ON, 96 km/h
(60 mph), Flat road)
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
DTC 71 EGR System Malfunction
EG±564± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

Malfunction: Open in EGR Gas Temp. Sensor Circuit
(1) Disconnect the EFI No.1 fuse (30A) for 10 sec. or more, with IG switch OFF.
Initiate test mode (Connect terminal TE2 and E1 of data link connector 2 with IG
switch OFF).
(2) Start the engine and warm up.
(3) Idle the engine for 3 min.
(4) With the A/C ON and transmission in 5th position (A/T in 3rd speed) drive at 88 96
km/h (55 60 mph) for 4 min or less.
HINT: If a malfunction exists, the malfunction indicator lamp will light up during step (4).
NOTICE: If the conditions in this test are not strictly followed, detection of the malfunction
will not be possible.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±565

INSPECTION PROCEDURE
(See page EG±310)
(See page IN±30).
(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Warm up engine to normal operating temperature.
Measure voltage between terminal EGR of engine con-
trol module connector and body ground.
Voltage: 9 Ð 14 V
Check voltage between terminal EGR of engine control module connector
and body ground.
Check for open and short in harness and connector between EFI main relay
and VSV for EGR, VSV for EGR and engine control module (See page IN±30).
Check resistance between terminals of VSV for EGR.
Repair or replace harness or connector.
Check and replace engine control module.
Remove VSV for EGR. (See page EG±310)
Measure resistance between terminals of VSV for
EGR.
Resistance: 30 Ð 34  at 20°C (68°F)
Replace VSV for EGR. EG±566
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(See page EG±180).
Remove EGR gas temp. sensor.
Measure resistance between terminals of EGR gas
temp. sensor connector.
Resistance: 64 Ð 97k at 50°C (122°F)
11 Ð 1 6k at 100°C (212°F)
2 Ð
k at 150°C (302°F)
Check EGR system (See page EG±180).
Repair EGR system.
Check resistance of EGR gas temp. sensor.
Replace EGR gas temp. sensor.
Repair or replace harness or connector.
Check and replace engine control module.
Check for open in harness and connector between EGR gas temp. sensor
and engine control module. (See page IN±30).
EGR Gas Temp. Sensor
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±567