TOYOTA SUPRA 1986 Service Repair Manual

Diagnosis Inspection (Normal Mode)
MALFUNCTION INDICATOR LAMP
CHECK
1. The Malfunction Indicator Lamp will come on when the
ignition switch is turned ON and the engine is not running.
HINT: If the malfunction indicator lamp does not light up, pro-
ceed to troubleshooting of the telltale light RH
(See page BE±48).
2. When the engine is started, the malfunction indicator lamp
should go off.
If the light remains on, the diagnosis system has detected a
malfunction or abnormality in the system.
DIAGNOSTIC TROUBLE CODE CHECK
1. Turn ignition switch ON.
2. Using SST, connect terminals between TE1 and E1 of data
link connector 1 or 2.
SST 09843±18020
3. Read the diagnostic trouble code from malfunction indicator
lamp.
HINT: If a diagnostic trouble code is not output, check the TE1
terminal circuit (See page EG±484).
As an example, the blinking patterns for codes; normal, 12
and 31 are as shown on the illustration.
4. Check the details of the malfunction using the diagnostic
trouble code table on page EG±388.
5. After completing the check, disconnect terminals TE1 and
E1, and turn off the display.
HINT: In the event of 2 or more malfunction codes, indication
will begin from the smaller numbered code and continue in
order to the larger.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±385

Diagnosis Inspection (Test Mode)
Compared to the normal mode, the test mode has an in-
creased sensing ability to detect malfunctions.
It can also detect malfunctions in the starter signal circuit, the
IDL contact signal of the throttle position sensor, air condi-
tioning signal and park/neutral position switch signal.
Furthermore, the same diagnostic items which are detected
in the normal mode can also be detected in the test mode.
DIAGNOSTIC TROUBLE CODE CHECK
1. Initial conditions.
(a) Battery voltage 11 V or more
(b) Throttle valve fully closed
(c) Transmission in neutral position
(d) Air conditioning switched OFF
2. Turn ignition switch OFF
3. Using SST, connect terminals TE2 and E1 of the data link
connector 2.
SST 09843±18020
4. Turn ignition switch ON.
HINT:
wTo confirm that the test mode is operating, check that the
malfunction indicator lamp flashes when the ignition
switch is turned to ON.
wIf the malfunction indicator lamp does not flash, proceed
to troubleshooting of the TE2 terminal circuit on page
EG±484.
5. Start the engine.
6. Simulate the conditions of the malfunction described by the
customer.
7. After the road test, using SST, connect terminals TE1 and E1
of the data link connector 2.
SST 09843±18020
8. Read the diagnostic trouble code on malfunction indicator
lamp on the telltale light RH (See page EG±385).
9. After completing the check, disconnect terminals TE1, TE2
and E1, and turn off the display.
HINT:
wThe test mode will not start if terminals TE2 and E1 are
connected after the ignition switch is turned ON.
wWhen the engine is not cranked, diagnostic trouble
codes º43º (Starter signal) output, but this is not
abnormal.
wWhen the automatic transmission shift lever is in the ºDº,
º2º, ºLº or ºRº shift position, or when the air conditioning
is on or when the accelerator pedal is depressed, code
º51º (Switch condition signal) is output, but this is not
abnormal. EG±386
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

DIAGNOSTIC TROUBLE CODE CHECK
USING TOYOTA HAND±HELD TESTER
1. Hook up the TOYOTA hand±held tester to the DLC2.
2. Read the diagnostic trouble codes by following the prompts
on the tester screen.
Please refer to the TOYOTA hand±held tester operation's
manual for further details.
DIAGNOSTIC TROUBLE CODE CLEARANCE
1. After repair of the trouble areas, the diagnostic trouble code
retained in the ECM memory must be cleared out by
removing the EFI No.1 fuse (30A) from R/B No.2 for 10
seconds or more, with the ignition switch OFF.
HINT:
wCancellation can also be done by removing the negative
(±) terminal cable from the battery, but in this case, other
memory systems (clock, etc.) will also be cancelled out.
wIf it is necessary to work on engine components
requiring removal of the negative (±) terminal cable from
the battery, a check must first be made to see if a
diagnostic trouble code has been recorded.
2. After cancellation, road test the vehicle to check that a normal
code is now read on the malfunction indicator lamp.
If the same diagnostic trouble code appears, it indicates that
the trouble area has not been repaired thoroughly.
ECM DATA MONITOR USING TOYOTA
HAND±HELD TESTER
1. Hook up the TOYOTA hand±held tester to the DLC2.
2. Monitor the ECM data by following the prompts on the tester
screen.
HINT: TOYOTA hand±held tester has a ºSnapshotº function which
records the monitored data.
Please refer to TOYOTA hand±held tester operator's manual for
further details.
ECM TERMINAL VALUES MEASUREMENT
USING TOYOTA BREAK±OUT±BOX AND
TOYOTA HAND±HELD TESTER
1. Hook up the TOYOTA break±out±box and TOYOTA
handheld tester to the vehicle.
2. Read the ECM input/output values by following the prompts
on the tester screen.
HINT: TOYOTA hand±held tester has a ºSnapshotº function. This
records the measured values and is effective in the diagnosis of
intermittent problems.
Please refer to TOYOTA hand±held tester/TOYOTA break±out
box operator's manual for further details.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±387

DIAGNOSTIC TROUBLE CODE CHART
HINT: Parameters listed in the chart may not be exactly the same as your reading due to type of the instruments
or other factors.
~
DTC
No.Number of
MIL BlinksCircuitDiagnostic Trouble Code Detecting Condition
NormalNo code is recorded.
G, NE Signal
(No.1)
G, NE Signal
(No.2)
Ignition Signal
A/T Control
Signal
(Main heated *3)
Oxygen
Sensor Signal
(Fr)
No NE or G1 and G2 signal to ECM for 2 sec. or more after cranking
Open in ªG
º circuit
No NE signal to ECM for 0.1 sec. or more at 1,000 rpm or more
NE signal does not pulse 12 times to ECM during the interval between
G1 and G2 pulses
No IGF signal to ECM for 6 consecutive IGT signals
Fault in communications between the engine CPU and A/T CPU in the
ECM
(1)*3Open or short in heater circuit of main heated oxygen sensor (Fr)
for 0.5 sec. or more
(2) (Main heated*3) oxygen sensor (Fr) signal voltage is reduced to
between 0.35 V and 0.70 V for 90 sec. under conditions
(a) ~ (d):
(2 trip detection logic)*4
(a) Engine coolant temp.: Between 80°C (176°F) and
95°C (203°F)
(b) Engine speed: 1,500 rpm or more
(c) Load driving (example A/T in in Overdrive, (5th for M/T),
A/C ON, Flat road, 80 km/H (50 mph))
(d) (Main heated*
3) oxygen sensor (Fr) signal voltage:
Alternating above and below 0.45 V
*3, 4: See page EG±396, 397. EG±388
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

If a malfunction code is displayed during the diagnostic trouble code check in test mode, check the circuit for
that code listed in the table below (Proceed to the page given for that circuit).
EG±409
EG±412
EG±413
EG±418
EG±419
Malfunction
Indicator
Lamp*
1Trouble Area
Normal
ModeTest
Mode
See pageMemory*2
ON
ON
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
N.A.
ON
ON
ON
ON

Open or short in NE, G circuit

Distributor

Open or short in STA circuit

ECM

Open or short in NE circuit

Distributor

ECM

Open or short in NE circuit

Distributor

ECM

Open or short in IGT or IGT circuit from igniter to ECM

Igniter

ECM

ECM

Open or short in heater circuit of main heated oxygen
sensor (Fr)

Main heated oxygen sensor (Fr) heater

ECM

(Main heated*3) oxygen sensor (Fr) circuit

(Main heated*3) oxygen sensor (Fr)
*1, 2, 3: See page EG±396
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±389

DTC
No.Number of
MIL BlinksCircuitDiagnostic Trouble Code Detecting Condition
Engine Coolant
Temp. Sensor
Circuit
Intake Air Temp.
Sensor Signal
Air±Fuel Ratio
Lean Malfunction
Open or short in engine coolant temp. sensor circuit for 0.5 sec.
or more
Open or short in intake air temp. sensor circuit for 0.5 sec. or
more
(1) (Main heated*3) oxygen sensor voltage is 0.45 V or less (lean)
for 90 sec. under conditions (a) and (b):
(2 trip detection logic)*
4
(a) Engine speed: 1,500 rpm or more
(b) Engine coolant temp.: 70°C (158°F) or more
(2)*3Difference of air±fuel ratio feedback compensation value
between front (no.1 ~ 3 cylinders) and rear (No.4 ~ 6
cylinders) is more tan 15 percentage for 20 sec. or more
under conditions (a) and (b):
(2 trip detection logic)*
4
(a) Engine speed: 2,000 rpm or more
(b) Engine coolant temp.: Between 60°C (140°F) and
95°C (203°F)
(3)*3Engine speed varies by more than 15 rpm over the preceding
crank angle period during a period o 20 sec. or more under
conditions (a) and (b):
(2 trip detection logic)*
4
(a) Engine speed: Idling
(b) Engine coolant temp.: Between 60°C (140°F) and
95°C (203°F)
*3, 4: See page EG±396 397. EG±390
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

 
 
 Trouble Area
 
 
 
Malfunction
Indicator
Lamp*
1
 
 
 Memory*2
 
 
 See page
 
 
Trouble Area
 
 
Normal
Mode 
 
Test
Mode 
 
Memory
 
 
See page
 
 
 
 

Open or short in engine coolant temp. sensor circuit

Engine coolant temp. sensor

ECM
 
 
 
 
ON
 
 
 
 
ON
 
 
 
 

 
 
 
 
EG±424
 
 
 
 
 

Open or short in intake air temp. sensor circuit

Intake air temp. sensor

ECM
 
 
 
 
 
ON
 
 
 
 
 
ON
 
 
 
 
 

 
 
 
 
 
EG±426
 
 
 
 
 

Open or short in (main heated*3) oxygen sensor circuit

(Main heated*3) oxygen sensor

Ignition system

ECM
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


Open or short in injector circuit

Fuel line pressure (injector leak, blockage)

Mechanical system malfunction (skipping teeth of timing belt)

Ignition system

Compression pressure (foreign object caught in valve)

Volume air flow meter (air intake)

ECM
 
 
 
 
 
 

ON
 
 
 
 
 
 

ON
 
 
 
 
 
 


 
 
 
 
 
 

EG±428
 
 
 
 
 
 
 

Open or short in injector circuit

Fuel line pressure (injector leak, blockage)

Mechanical system malfunction (skipping teeth of timing belt)

Ignition system

Compression pressure (foreign object caught in valve)

Volume air flow meter (air intake)

ECM
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
*1, 2, 3: See page EG±396.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±391

DTC
No.Number of
MIL BlinksCircuitDiagnostic Trouble Code Detecting Condition
Air±Fuel Ratio
Rich Malfunction
(1) Difference of air±fuel ratio feedback compensation value
between front (No.1 ~ 3 cylinders) and rear (No.4 ~ 6
cylinders) is more than 15 percentage for 20 sec. or
more under conditions(a) and (b):
(2 trip detection logic)*
4
(a) Engine speed: 2,000 rpm or more
(b) Engine coolant temp.: Between 60°C (140°F) and
95°C (203°F)
(2) Engine speed varies by more than 15 rpm over the preceding
crank angle period during a period o 20 sec. or more under
conditions (a) and (b):
(2 trip detection logic)*
4
(a) Engine speed: 2,000 rpm or more
(b) Engine coolant temp.: Between 60°C (140°F) and
95°C (203°F)
(1) Open or short in heater circuit of sub heated oxygen
sensor for 0.5 sec. or more
(2) Main heated oxygen sensor signal is 0.45 V or more and sub
oxygen sensor signal is 0.45 V or less under conditions (a) ~ (c):
(2 trip detection logic)*
4
(a) Engine coolant temp.: 80°C (176°F) or more
(b) Engine speed: 1,500 rpm or more
(c) Accel. pedal: Fully depressed for 2 sec. or more
(1)*3Open or short in heater circuit of main heated oxygen
sensor (Rr) for 0.5 sec. or more|
(2) (Main heated*3) oxygen sensor (Rr) signal voltage is
reduced to between 0.35 V and 0.70 V for 90 sec.
under conditions (a) ~ (d)
(2 trip detection logic)*
4
(b) Engine coolant temp.: Between 80°C (176°F)
and 95°C (203°F)
(b) Engine speed: 1,500 rpm or more.
(c) Load driving (Example A/T in Overdrive (5th for M/T),
A/C ON, Flat road, 80 km/h (50 mph))
(d) (Main heated*3) oxygen sensor (Rr) signal voltage:
Alternating above and below 0.45 V
Sub Heated
Oxygen Sensor
Signal
(Main heated*3)
Oxygen Sensor
Signal (Rr)
*3, 4: See page EG±396, 397 EG±392
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

 
 
 Trouble Area
 
 
 
Malfunction
Indicator
Lamp*
1
 
 
 Memory*2
 
 
 See page
 
 
Trouble Area
 
 
Normal
Mode 
 
Test
Mode 
 
Memory
 
 
See page
 
 
 
 
 
 
 

Open or short in injector circuit

Fuel line pressure (injector leak, blockage)

Mechanical system malfunction (skipping teeth of timing belt)

Ignition system

Compression pressure (foreign object caught in valve)

Volume air flow meter (air intake)

ECM
 
 
 
 
 
 
 ON
 
 
 
 
 
 
 ON
 
 
 
 
 
 
 
 
 
 
 
 
 
 EG±428
 
 
 
 
 
 

Open or short in injector circuit

Fuel line pressure (injector leak, blockage)

Mechanical system malfunction (skipping teeth of timing belt)

Ignition system

Compression pressure (foreign object caught in valve)

Volume air flow meter (air intake)

ECM
 
 
 
 
 
 
ON
 
 
 
 
 
 
ON
 
 
 
 
 
 

 
 
 
 
 
 
EG 428
 
 
 

Open or short in heater circuit of sub heated oxygen sensor

Sub heated oxygen sensor

ECM
 
 
 
ON
 
 
 
N.A.
 
 
 
 
 
 
 
 
 
 
 
 

Open or short in sub heated oxygen sensor circuit

Sub heated oxygen sensor

ECM
 
 
 
 
 
 
ON
 
 
 
 
 
 
ON
 
 
 
 
 
 

 
 
 
 
 
 
EG±434
 
 
 

Open or short in heater circuit of main heated oxygen sensor (Rr)

Main heated oxygen sensor (Rr) heater

ECM
 
 
 
ON
 
 
 
N.A.
 
 
 
 
 
 
 
 
 
 
 
 
 

(Main heated*3) oxygen sensor (Rr) circuit

(Main heated*3) oxygen sensor (Rr)
 
 
 
 
 
 
 
ON
 
 
 
 
 
 
 
ON
 
 
 
 
 
 
 

 
 
 
 
 
 
 
EG±419
*1, 2, 3: See page EG±396.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±393

DTC
No.Number of
MIL BlinksCircuitDiagnostic Trouble Code Detecting Condition
Volume Air
Flow Meter
Signal
Barometric
Pressure
Sensor Signal
Throttle Position
Sensor Signal
No.1 Vehicle
Speed Sensor
Signal
(for A/T)
No.1 Vehicle
Speed Sensor
Signal
(for A/T)
Starter Signal
Knock Sensor
Signal
(front side)
Knock Control
Signal
Knock Sensor
Signal (rear side)
All conditions below are detected:
(a) No volume air flow meter signal to ECM for 2 sec. when
engine speed is above 300 rpm
(b) Engine stall
Open or short in BARO sensor circuit for 0.5 sec. or more
Open or short in throttle position sensor circuit for 0.5 sec. or
more
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
All conditions below are detected continuously for 8 sec. or more:
(a) No.1 vehicle speed signal: 0 km/h (mph)
(b) Engine speed: 2,000 rpm and 5,000 rpm
(c) Engine coolant temp.: 80°C (176°F) or more
(d) Load driving
No starter signal to ECM
No. No.1 knock sensor signal to ECM for 4 crank revolutions
with engine speed between 1,600 rpm and 5,200 rpm
Engine control computer (for knock control) malfunction at en-
gine speed between 650 rpm and 5,200 rpm
No No.2 knock sensor signal to ECM for 4 crank revolutions with
engine speed between 1,600 rpm and 5,200 rpm
EG±394± ENGINE2JZ±GE ENGINE TROUBLESHOOTING