TOYOTA SUPRA 1986 Service Workshop Manual

Suspect area
See page
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 not
start
Difficult to
start
Poor Idling
Engine Stall
Poor
Driveability
Back up power source circuitECM power source circuitPark/neutral position switch circuitSwitch condition signal circuitEGR systemStarter signal circuitMass air flow meter circuitInjector circuitIAC valve circuitFuel pump control circuitA/C signal circuit (Compressor circuit)Turbo control circuitVSV circuit for fuel Pressure ControlCompressionSpark plugIgnition signal circuit (Spark test)Starter and Starter relayIgnition coilEngine control module (ECM)Theft deterrent ECUA/T faulty
EG±544EG±559EG±564EG±571EG±574EG±576EG±581EG±583EG±586EG±568EG±595EG±589AC±62ST±3
,
12
IG±21IG±23IG±22EG±9AT2±101BE±123IN±35
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±514
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

CIRCUIT DESCRIPTION
Camshaft position sensors (G1 and G2 signals) are mounted on the intake side of the cylinder head
and the crankshaft position sensor (NE signal) is mounted on the oil pump body. These sensors consist
of a timing rotor and pick up coil.
The G1, G2 timing rotors have 1 tooth each on their outer circumference and are mounted on the intake
camshaft.
When the intake camshaft rotates, the protrusion on the timing rotors and the air gap on the pick up
coil change, causing fluctions in the magnetic field and generating an electromotive force in the pick
up coil.
The NE timing rotor has 12 teeth and is mounted on the crankshaft. The NE signal sensor generates
12 NE signals per engine revolution. The ECM detects the standard crankshaft angle based on the G1,
G2 signals, and the actual crankshaft angle and the engine speed by the NE signals.
DTC No.Diagnostic Trouble Code Detecting ConditionTrouble Area
No ªNEº or ªG1º and ªG2º signal to ECM for 2 sec.
or more after cranking

Open or short in crankshaft position
sensor, camshaft position sensor No.1, No.2
circuit

Crankshaft position sensor

Camshaft position sensor No.1, No.2

Starter

ECM
CIRCUIT INSPECTION
DTC 12 G NE Signal Circuit (No.1)
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±515

INSPECTION PROCEDURE
(See page IG±30).
Check crankshaft position sensor, camshaft position sensors No.1, No.2.
For crankshaft position sensor, remove crankshaft posi-
tion sensor (See page IG±30).
For camshaft position sensor No.1, No.2, disconnect
camshaft position sensor No.1 No.2 connectors.
Measure resistance of crankshaft position sensor, cam-
shaft position sensor No.1 and No.2.
Camshaft
Position Sensor
No.1 and No.2
Camshaft
Position
Sensor
ªColdº is from Ð 10°C (14°F) to 50°C (122°F) and ªHotº
is from 50°C (122°F) to 100°C (212°F).
EG±516± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

Check for open and short in harness and connector between engine control
module and each sensor (See page IN±30).

During cranking or idling, check waveforms between
terminals G1, G2 and G1
, G2
, NE and NE
of
engine control module.
HINT: The correct waveforms are as shown.
Inspect sensor installation and teeth of timing rotor.
INSPECTION USING OSCILLOSCOPE
Replace crankshaft position sensor, camshaft
position sensor No.1, No.2.
Tighten the sensor. Replace timing rotor (Intake
camshaft, crankshaft timing pulley).
Check and replace engine control module.
Repair or replace harness or connector.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±517

DTC 13 G NE Signal Circuit (No.2)
CIRCUIT DESCRIPTION
Refer to G, NE signal circuit (No.1) on page EG±515
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble Area
 
 
 
 
 
 
 
 
No NE signal to ECM for 0.1 sec. or more at
1,000 rpm or more
 
 
 
 

Open or short in crankshaft position
sensor circuit

Crankshaft position sensor

ECM
 
 
 
 
 
 
13
 
 
 
 
 
 
NE signal does not pulse 12 times to ECM
during the interval between G1 and G2 pulses
 
 
 
 
 
 

Open or short in crankshaft position
sensor circuit

Mechanical system malfunction (skipping
teeth of timing belt, belt stretched)

Crankshaft position sensor

ECM
 
 
 
 
 
 
 
 
Deviation in G (G1, G2) and NE signal
Continues for 3 sec. during idling
throttle fully closed after engine warmed up 
 
 
 

Mechanical system malfunction (skipping
teeth of timing belt, belt stretched)

Camshaft position sensor No. 1, No.2

ECM
INSPECTION PROCEDURE
Inspect sensor installation. Check if any teeth of NE signal plate are broken.
Tighten sensor.
Replace timing rotor.
Adjust valve timing (repair or replace timing belt).
Check valve timing (Check for loose and jumping teeth of timing belt
(See page EG±33)).
Check for intermittent problems.
(See page EG±505)
EG±518± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

DTC 14 Ignition Signal Circuit
CIRCUIT DESCRIPTION
The ECM determines the ignition timing, turns on Tr1 at a predetermined angle (°CA) before the desired ignition
timing and outputs an ignition signal (IGT) º1º to the igniter.
Since the width of the IGT signal is constant, the dwell angle control circuit in the igniter determines the time
the control circuit starts primary current flow to the ignition coil based on the engine rpm and ignition timing one
revolution ago, that is, the time the Tr
2 turns on.
When it reaches the ignition timing, the ECM turns Tr
1 off and outputs the IGT signal ºOº.
This turns Tr
2 off, interrupting the primary current flow and generating a high voltage in the secondary coil which
causes the spark plug to spark. Also, by the counter electromotive force generated when the primary current
is interrupted, the igniter sends an ignition confirmation signal (IGF) to the ECM.
The ECM stops fuel injection as a fail safe function when the IGF signal is not input to the ECM.
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble Area 
 
 
 
14
 
 
 
 
No IGF signal to ECM for 4 ~ 7 consecutive
IGT signals with engine speed less than
3,000 rpm
 
 
 
 

Open or short in IGF circuit from igniter to
ECM

Igniter

ECM
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±519

Check for spark.
(1) Remove ignition coil. (See page IG±26)
(2) Remove spark plug.
(3) Install the spark plug to the ignition coil, and connect
the ignition coil connector.
(4) Ground the spark plug.
Check if spark occurs while engine is being cranked.
To prevent excess fuel being injected from injectors dur-
ing this test, don't crank the engine for more than 1Ð2
seconds at a time.
Check for open and short in harness and connector in IGF signal circuit
between engine control module and igniter (See page IN±30).
Repair or replace harness or connector.
Replace igniter.
Check and replace engine control module.
Disconnect igniter connector and check voltage between terminal IGF of
engine control module connector and body ground.
(1) Disconnect igniter connector.
(2) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(3) Turn ignition switch ON.
Measure voltage between terminal IGF of engine con-
trol module connector and body ground.
Voltage: 4.5 Ð 5.5 V
INSPECTION PROCEDURE
EG±520± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(See page EG±510)

During idling, check waveforms between termi±
nals IGT1, IGF and E1 of engine control module.
HINT: The correct rectangular waveforms are as
shown, IGT2, IGT3, IGT4, IGT5 and IGT6
signal waveforms are same as IGT1 signal
waveform.
Check voltage between terminal IGT (1 ~ 6) of engine control module
connector and body ground.
Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
Measure voltage between terminal IGT (1 ~ 6) of engine
control module connector and body ground when en-
gine is cranked.
Voltage: 0.5 Ð 1.0 V
(Neither 0 V nor 5 V)
Check voltage between terminal 2 of igniter connector (I2) and body ground.
Disconnect igniter connector.
Measure voltage between terminal 2 of igniter connec-
tor (I2) and body ground, when ignition switch is turned
to ªONº and and ªSTARTº position.
Voltage: 9 Ð 14 V
Check and repair igniter power source circuit.
ReferenceINSPECTION USING OSCILLOSCOPE
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±521

Check for open and short in harness and connector between ignition
switch and ignition coil, ignition coil and igniter (See page IN±30).
Disconnect ignition coil connector.
(See page IG±23)
Measure resistance between terminals of ignition coil
connector.
Repair or replace harness or connector.
Check ignition coil.
ªColdº is from Ð 10°C (14°F) to 50°C (122°F) and ªHotº is
from 50°C (122°F) to 100°C (212°F).
Replace ignition coil.
Replace igniter.
EG±522± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

Disconnect igniter connector and check voltage between terminal
IGT (1 ~ 6) of engine control module connector and body ground.
Disconnect igniter connector.
Measure voltage between terminal IGT (1 ~ 6) of engine
control module connector and body ground when engine
is cranked.
Voltage: 0.5 Ð 1.0 V
(Neither 0 V nor 5 V)
Replace igniter.
Check for open and short in harness and connector in IGT (1 ~ 6) signal
circuit between engine control module and igniter (See page IN±30).

During idling, check waveforms between terminals
IGF1, IGF and E1 of engine control module.
HINT: The correct rectangular waveforms are as shown,
IGT2, IGT3, IGT4, IGT5 and IGT6 signal wave±
forms are same as IGT1 signal waveform.
Repair or replace harness or connector.
Check and replace engine control module.
ReferenceINSPECTION USING OSCILLOSCOPE
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±523