1986 TOYOTA SUPRA turn signal

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±598.
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±491).
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±492
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

FAIL±SAFE CHART
If any of the following codes is detected, the ECM enters fail±safe mode.
 DTC No. Fail±Safe Operation Fail±Safe Deactivation Conditions
 
 14
 
 Fuel cut
 
 6 IGF signals detected in 6 consecutive
ignitions
 16 Torque control prohibited Returned to normal condition 
 22
 
 THW is fixed at 80°C (176°F)
 
 Returned to normal condition
 24 THA is fixed at 20°C (68°F) Returned to normal condition
 
 
 
 
 
 
31
 
 
 
 
 
 
Volume of air flowing is measured by turbo pressure
Sensor to determine injection volume and ignition
Timing
 
 
 
 
 
 
Returned to normal condition
 
 34
 
 Fuel cut
 
 Returned to normal condition
  Turbo  
  
Turbo
Pressure Fuel cut Returned to normal condition
 35 Sensor  
 
 
35
 
 
BARO
Sensor 
 
Atmospheric pressure is fixed at
101.3 kPa (760 mmHg, 29.92 inVHg) 
 Returned to normal condition
 
 
 
 
41
 
 
 
 
VTA1 is fixed at closed throttle position
 
 
 
 
The following must each be repeated at
least 2 times consecutively:

0.1 V
VTA1
0.95 V

IDL: ON
 
 
 
47
 
 
 
VTA2 is fixed at wide open throttle
Position 
 
 
The following must be repeated at least 2
times consecutively

0.1 V
VTA2
0.95 V
 52 Max. timing retardation IG switch OFF
 53 Max. timing retardation Returned to normal condition
 55 Max. timing retardation IG switch OFF
Back±Up Function
If there is trouble with the program in the ECM and the ignition signals (IGT) are not output from the microcomput-
er, the ECM controls fuel injection and ignition timing at predetermined levels as a back±up function to make
it possible to continue to operate the vehicle.
Furthermore, the injection duration is calculated from the starting signal (STA) and the throttle position signal
(IDL). Also, the ignition timing is fixed at the initial ignition timing, 10
°BTDC, without relation to the engine speed.
HINT: If the engine is controlled by the back±up function, the malfunction indicator lamp lights up to warn the
driver of the malfunction but the diagnostic trouble code is not output. EG±504
± 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

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

INSPECTION PROCEDURE
PNP...Go to page EG±574.
(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.
(For checking terminal IDL, disconnect the
vacuum hose from the throttle body, then ap-
ply vacuum to the throttle opener (See page
EG±292)).
((For checking terminal A/C, start the engine.)
(4) connect terminals TE1 and E1 of DLC2.
Check if code ª51º is output by the malfunction indi-
cator lamp.
*: Before the STA signal is input (ST is not ON), diag±
nostic trouble code 43 is also output.
Diagnostic trouble code 42 is output with vehicle speed
5 km/h (3 mph) or below.
Check output condition of diagnostic trouble code 51.
IDL1...Go to step [2].
PNP....Go to page Eg±574.
A/C....Go to step [3].
Proceed to next circuit inspection shown on matrix
chart (See page Eg±514).
Check output condition of diagnostic trouble code 51.
Throttle Position
Sensor (IDL1)
Condition
Park/Neutral Posi-
tion Switch (PNP)
Code
Accelerator pedal
released
Accelerator pedal
depressed
A/C SW ON
A/C SW OFFA/C Switch (A/C)
P or N position
R, D, 2 or L position
EG±572± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

ECM Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned on, battery volt-
age is applied to the terminal IGSW of the ECM,
and the main relay control circuit in the ECM sends
a signal to the terminal M±REL of the ECM, switch-
ing on the main relay. This signal causes current to
flow to the coil, closing the contacts of the main
relay and supplying power to the terminal + B of the
ECM.
If the ignition switch is turned off, the ECM contin-
ues to switch on the main relay for a maximum of
2 seconds for the initial setting of the IAC valve. EG±576
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING