1986 TOYOTA SUPRA air condition

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

Check idle speed.
Check ignition timing.
Check idle speed.
(1) Shift transmission into ªNº position.
(2) Warm up engine to normal operating tempera±
ture.
(3) Switch OFF all accessories.
(4) Switch OFF air conditioning.
(5) Connect tachometer test probe to terminal IG
of data link connector 1.
Check idle speed.
Idle speed: 700
50 rpm
wNEVER allow tachometer test probe to touch
ground as it could result in damage to igniter
and/or ignition coil.
wAs some tachometers are not compatible with
this ignition system, we recommend that you
confirm compatibility of your unit become use.
Proceed to matrix chart of problem symptoms
on page EG±408.
Proceed to page EG±18 and continue to trouble-
shoot.
Proceed to matrix chart of problem symptoms
on page EG±408.
(1) Shift transmission into ªNº position.
(2) Warm up engine to normal operating tempera±
ture.
(3) Keep the engine speed at idle.
(4) Using SST, connect terminals TE1 and E1 of data
link connector 1.
SST 09843±18020
(5) Connect a timing light probe to No.1 high±ten-
sion cord.
Check ignitiion timing.
Ignition timing: 10
2° BTDC @ idle
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±401

(See page EG±439)
(See page EG±472)
(See page EG±415)
(See page EG±415)
(See page EG±410)
(See page EG±410)
Symbols (Terminals No.)STD Voltage (V)Condition
Always
IG switch ON
IG switch ON and apply vacuum to the
throttle opener Throttle valve fully closed
IG switch ON
IG switch ON
Throttle valve fully opened
IG switch ON
Throttle valve fully closed
IG switch ON
Throttle valve fully opened
IdlingPulse generation
Idling, Intake air temp. 0°C (32°F) to 80°C
(176°F)
Idling, Engine coolant temp. 60°C (140°F) to
120°C (248°F)
Cranking
IG switch ON
Idling
Idling
IG switch ON
IG switch ON
IG switch ON
Idling
Idling
Idling
Idling
Idling
Pulse generation
Pulse generation
Pulse generation
Pulse generation
Pulse generation
Pulse generation
STANDARD VALUE OF ECM TERMINALS
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±405

MATRIX CHART OF PROBLEM SYMPTOMS
When the malfunction code is not confirmed in the diagnostic trouble code check and the problem still can not
be confirmed in the basic inspection, proceed to this matrix chart and troubleshoot according to the numbered
order given below.
EG±438EG±438EG±453EG±460EG±463EG±465EG±470EG±472EG±475EG±457EG±481AC±62ST±3, 12IG±4IG±5IG±7IG±7EG±9AT2±81BE±123IN±35
See page
Suspect area
Symptom
Engine does not crank
No initial combustion
No complete combustion
Engine cranks normally
Cold engine
Hot engine
Incorrect first idle
High engine idle speed
Low engine idle speed
Rough idling
Hunting
Hesitation/Poor acceleration
Muffler explosion (after fire)
Surging
Soon after starting
After accelerator pedal depressed
After accelerator pedal released
During A/C operation
When shifting N to D
Does notstart
Difficult tostart
Poor Idling
Poor
Driveability
Engine Stall
Volume air flow meter circuitECM power source circuitPark/neutral position switch circuitSwitch condition signal circuitEGR systemStarter signal circuitStarter and Starter relayA/C signal circuit (Compressor circuit)VSV circuit for fuel pressure controlFuel pump control circuitIAC valve circuitInjector circuitBack up power source circuitIgnition coilSpark plugIgnition signal circuit (Spark test)CompressionA/T faultyDistributorEngine control module (ECM)Theft deterrent ECU
EG±408± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

DTC 16 A T Control Signal Malfunction
CIRCUIT DESCRIPTION
The signal from the A/T CPU retards the ignition timing of the engine during A/T gear shifting, thus momentarily
reducing torque output of the engine for smooth clutch operation inside the transmission and reduced shift
shock.
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble Area 
16
 
Fault in communications between the engine CPU
 

ECM 16 Fault in communications between the engine CPU
and A/T CPU in the ECM 
ECM
If the ECM detects the diagnostic trouble code º16º in memory, it prohibits the torque control of the A/T which
performs smooth gear shifting.
INSPECTION PROCEDURE
Are there any otheer codes (besides Code 16) being output?
Repair engine control module.
Go to relevant diagnostic trouble code chart.
EG±418± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

CIRCUIT DESCRIPTION
To obtain a high purification rate for the Co, Hc and NOx components of the exhaust gas, a three±way catalytic
converter is used, but for most efficient use of the three±way catalytic converter, the air±fuel ratio must be pre-
cisely controlled so that it is always close to the stoichiometric air±fuel ratio.
The oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoi-
chiometric air±fuel ratio. This characteristic is used to detect the oxygen concentration in the exhaust gas and
provide feedback to the computer for control of the air fuel ratio.
When the air±fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the oxygen sen-
sor informs the ECM of the LEAN condition (small electromotive force: 0 V).
When the air±fuel ratio is RICHER than the stoichiometric air±fuel ratio the oxygen concentration in the exhaust
gas is reduced and the oxygen sensor informs the ECM of the RICH condition (large electromotive force: V).
The ECM judges by the electromotive force from the oxygen sensor whether the air±fuel ratio is RICH or LEAn
and controls the injection duration accordingly. However, if malfunction of the oxygen sensor causes an output
of abnormal electromotive force, the ECM is unable to perform accurate air±fuel ratio control.
The main heated oxygen sensors include a heater which heats the Zirconia element. The heater is controlled
by the ECM. When the intake air volume is low t(the temperature of the exhaust has is low) current flows to
the heater to heat the sensor for accurate oxygen concentration detection.)
Flange
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Heater*
1
Coating (Ceramic)
Ideal Air±Fuel Mixture
Richer Ð Air Fuel ratio Ð Leaner
Trouble AreaDTC No.Diagnostic Trouble Code Detecting Condition
Exhaust Gas
Output Voltage
(1)*1Open or snort in heater circuit of main heated
oxygen sensor for 0.5 sec. or more.
(2) (Main heated*1) oxygen sensor signal voltage is
reduced to between 0.35 V and 0.70 V for 60
sec. under conditions (a) ~ (d):
(2) trip detection logic)*
2
(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 Overdrive
(5th for M/T), A/C ON, Flat road, 80 km/h (50
mph))
(d) (Main heated*
1) oxygen sensor signal
voltage: Alternating above and below 0.45 V
Atmosphere

Open or short in heater circuit of main heated
oxygen sensor

Main heated oxygen sensor heater

ECM

(Main heated*
1) oxygen sensor circuit

(Main heated*1) oxygen sensor
HINT: Diagnostic trouble code ª21º is for the (main heated*1) oxygen sensor (Fr) circuit.
Diagnostic trouble code ª28º is for the (main heated*
1) oxygen sensor (Rr) circuit.
*1: Main heated oxygen sensor ONLY for California specification vehicles.
*2: See page EG±397.
DTC 21 28 (Main Heated*1) Oxygen Sensor Circuit
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±419

CIRCUIT DESCRIPTION (Cont'd)
DIAGNOSTIC TROUBLE CODE DETECTION DRIVING PATTERN
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 confirming that diagnostic
trouble code is no longer detected.
Malfunction: (Main heated() Oxygen Sensor Detection
(Vehicle Speed)
80 km/h (50 mph)
64 km/h (40 mph)
It is vital that this test routine is adhered to detect the malfunction:
(1) Disconnect the EFI No.1 fuse (30 A) 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 with all ACC switched OFF.
(3) Idle the engine for 3 min.
(4) Accelerate gradually within the range 1,300 ~ 1,700 rpm (dentered around 1,500 rpm) with
the A/C switched ON and D position for A/T (5th for M/T).
HINT:
Ensure engine rpm does NOT fall below 1200 rpm.

Gradually depress the accelerator pedal at a suitable rate to comply with the test
requirements on the above graph.

Never allow engine rpm to drop at any time during the test.
(5) Maintain the vehicle speed at 64 Ð 80 km/h (40 Ð 50 mph).
(6) Keep the vehicle running for Ð 2 min. after starting acceleration.
HINT: If a malfunction exists, the Malfunction Indicator Lamp will light up after approx. 60 sec.
from the start of acceleration.
NOTICE: If the conditions in this test are not strictly followed, detection of the malfunction
will not be possible.
*: Main heated oxygen sensor only for California specification vehicles EG±420
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

DTC 24 Intake Air Temp. Sensor Circuit
CIRCUIT DESCRIPTION
The intake air temp. sensor is built into the volume air flow meter and senses the intake air temperature.
The structure of the sensor and connection to the ECM is the same as in the engine coolant temp. sensor shown
on page EG±424.
If the ECM detects the diagnostic trouble code º24º, it operates the fail safe function in which the
intake air temper-
ature
is assumed to be 20°C (68°F).
 
 DTC No.
 
 Diagnostic Trouble Code Detecting Condition
 
 Trouble Area
 
24
 Open or short in intake air temp. sensor circuit for 
Open or short in intake air temp. sensor circuit

Intake air tempsensor 
 
24 
 
Oen or short in intake air tem . sensor circuit for
0.5 sec. or more 
 

Intake air temp. sensor

ECM
EG±426± ENGINE2JZ±GE ENGINE TROUBLESHOOTING