1986 TOYOTA SUPRA Service Repair Manual

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

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

Open or short in volume air flow meter circuit

Volume air flow meter

ECM
 
 
 
 
ON
 
 
 
 
N.A.
 
 
 
 

 
 
 
 
EG±438
 
 
 

ECM
 
 
 
ON
 
 
 
ON
 
 
 

 
 
 
EG±441
 
 
 
 

Open or short in throttle position sensor circuit

Throttle position sensor

ECM
 
 
 
 
ON
 
 
 
 
ON
 
 
 
 

 
 
 
 
EG±442
 
 
 
 
 
 
 
 
 

No.1 vehicle speed sensor

Telltale light RH

Open or short in No.1 vehicle speed sensor circuit

ECM
 
 
 
 
 
 
 
 
 
OFF
 
 
 
 
 
 
 
 
 
OFF
 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 
 
 
EG±445
 
 
 

Open or short in starter signal circuit

Open or short in ignition switch or starter relay circuit

ECM
 
 
 N.A.
 
 
 OFF
 
 
 X
 
 
 EG±448
 
 
 
 
 

Open or short in No.1 knock sensor circuit

No.1 knock sensor (looseness)

ECM
 
 
 
 
 
ON
 
 
 
 
 
N.A.
 
 
 
 
 

 
 
 
 
 
EG±450
 
 
 
 

ECM
 
 
 
 
ON
 
 
 
 
N.A.
 
 
 
 
X
 
 
 
 
EG±450
 
 
 
 
 

Open or short in No.2 knock sensor circuit

No.2 knock sensor (looseness)

ECM
 
 
 
 
 
ON
 
 
 
 
 
N.A.
 
 
 
 
 

 
 
 
 
 
EG±450
*1, 2: See page EG±396.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±395

DTC
No.Number of
MIL BlinksCircuitDiagnostic Trouble Code Detecting Condition
EGR System
Malfunction
Fuel Pump
Control Signal
Switch Condition
Signal
(1) 3 sec. or more after engine starts, with closed throttle posi±
tion switch OFF (IDL1)
(2) Park/neutral position switch: OFF
(Shift position in ªRº, ªDº, ª2º, or ªLº position)
(3) A/C switch ON
(3) Open or short in diagnostic signal line (DI) of fuel pump
ECU with engine speed 1,000 rpm or less
(2 trip detection logic)*
4
(2) Open in input circuit of fuel pump ECU (FPC) with engine
speed 1,000 rpm or less
(2 trip detection logic)*
4
(1) Open or short in fuel pump circuit for 1 sec. or more with
engine speed 1,000 rpm or less
(2 trip detection logic)*
4
EGR gas temp. is 70°C (158°F) or less for 1 Ð 4 min. under
conditions (a) and (b):
(2 trip detection logic)*
4
(a) Engine Coolant temp.: 63°C (145°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)
*1: ºONº displayed in the diagnostic mode column indicates that the Malfunction Indicator Lamp is lit up when
a malfunction is detected. ºOFFº indicates that the ºCHECKº does not light up during malfunction
diagnosis, even if a malfunction is detected. ºN.A.º indicates that the item is not included in malfunction
diagnosis.
*2: º
º in the memory column indicates that a diagnostic trouble code is recorded in the ECM memory when
a malfunction occurs. ºxº indicates that a diagnostic trouble code is not recorded in the ECM memory even
if a malfunction occurs. Accordingly, output of diagnostic results in normal or test mode is done with the
IG switch ON.
*3: Only for California specification vehicles. EG±396
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING