1986 TOYOTA SUPRA Service Repair Manual

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

G, NE signal circuit (No.2)
Engine coolant temp. sensor
circuit
Intake air temp. sensor circuit
Throttle position sensor
circuit
Sub±throttle position sensor
circuit
CircuitDTC
CHECK FOR INTERMITTENT PROBLEMS
As described in the preceding paragraph, abnormality detection
ability in the test mode is increased compared to that in the normal
mode, so that when intermittent problems occur in the ECM signal
circuits (G1, G2, NE, THW, THA, VTA1, VTA2) shown in the table
below, the appropriate diagnostic trouble code is output.
Accordingly, when the diagnostic trouble codes shown in the table
opposite (13, 22, 24, 41, 47) are output during the diagnostic
trouble code check, and inspection of the appropriate circuits re-
veals no abnormality, check for intermittent problems as described
below.
By checking for intermittent problems, the place where intermittent
problems are occurring due to poor contacts can be isolated.
CLEAR DIAGNOSTIC TROUBLE CODES
See page EG±493.
SET TEST MODE
1. With the ignition switch OFF, using SST, connect the
terminals TE2 and E1 of the data link connector 2.
SST 09843±18020
2. Start the engine and check to see the malfunction indicator
lamp goes off.
PERFORM A SIMULATION TEST
Using the symptom simulation (See page IN±24), apply vibration
to and pull lightly on the wire harness, connector or terminals in the
circuit indicated by the malfunction code.
In this test, if the malfunction indicator lamp lights up, it indicates
that the place where the wire harness, connector or terminals be-
ing pulled or vibrated has faulty contact. Check that point for loose
connections, dirt on the terminals, poor fit or other problems and
repair as necessary.
HINT: After cancelling out the diagnostic trouble code in memory
and set the test mode, if the malfunction indicator lamp does not
go off after the engine is started, check thoroughly for faulty con-
tacts, etc., then try the check again, if the malfunction indicator
lamp still does not go off, check and replace ECM.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±505

BASIC INSPECTION
In many cases, by carrying out the basic engine check shown in the following flow chart, the location causing
the problem can be found quickly and efficiently. Therefore, use of this check is essential in engine troubleshoot-
ing.
If there is a problem, and a normal code is displayed, proceed to the matrix chart of problem symptoms on page
EG±514. Make sure that every likely cause of the problem is checked.
Is battery positive voltage 11 V or more when engine is stopped?
Is engine cranked?
Does engine start?
Check air filter.
Charge or replace battery.
Proceed to matrix chart of problem symptom
on page EG±514.
Repair or replace.
Remove air filter.
Visually check that the air filter is not excessively
dirty or oily.
If necessary, clean the air filter with compressed
air. First blow from inside thoroughly, then blow
from outside of the air filter.
Charge or replace battery.
Is battery positive voltage 11 V or more when engine is stopped?
EG±506± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(See page EG±20)
Check idle speed.
Proceed to matrix chart of problem symp-
toms on page EG±514.
(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: 650  50 rpm

Never allow tachometer test probe to touch
ground as it could result in damage to igniter
and/or ignition coil.

As some tachometers are not compatible
with this ignition system, we recommended
that you confirm the compatibility of your
unit before use.
Check ignition timing.
(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 clip to the check wire.
(See page EG±20)
Check ignition timing.
Ignition timing: 10 2° BTDC @ idle
Proceed to matrix chart of problem symp-
toms on page EG±514.
Proceed to page EG±518 and continue to
troubleshoot.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±507

(See page
IG±26)
Check fuel pressure.
Proceed to page EG±264 and continue to
troubleshoot.
(1) Be sure that there is enough fuel in the tank.
(2) Turn ignition switch ON.
(3) Using SST, connect terminals FP and +B of
data link connector 1.
SST 09843±18020
Check that there is pressure in the hose from the fuel
filter.
If there is fuel pressure, you will hear the sound of fuel
flowing.
Never make a mistake with the terminal con-
nection position as this will cause a malfunc-
tion.
Check for spark.
Proceed to page IG±21 and continue to trou-
bleshoot.
Proceed to matrix chart of problem symptoms
on page EG±514.
(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 the injectors
during this test, don't crank the engine for more than 1
Ð 2 seconds at a time.
EG±508± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

PARTS LOCATION
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±509

STANDARD VALUE OF ECM TERMINALS
Connectors of the engine control module are waterproof and are
the bolt type.
For waterproof type connectors, in order to measure the voltage
of ECM terminals and the resistance of connected parts, connect
the inspection sub wire harness between the ECM and vehicle
wire harness, then do the inspection.
The inspection method of inserting a tester probe from the other
side of connector significantly reduces the waterproof perfor-
mance.
Disconnect the connector by fully loosening the bolt.
PREPARATION
1. Turn the ignition switch OFF.
2. Turn up the passenger side floor carpet.
(See page EG±324)
3. Remove the ECM protector.
4. Disconnect the connector from the ECM.
After completely loosening the bolt, the 2 parts of the connec-
tor can be separated.
NOTICE:
wDo not pull the wire harness when disconnecting the con-
nector.
wWhen disconnecting the connector, the ECM's back±up
power source is cut off, so the malfunction codes, etc. re-
corded in the ECM memory are cancelled.
wNever insert a tester probe or male terminal used for in-
spection purposes into the female terminal of the vehicle
wire harness. Otherwise, the female terminal may be wid-
ened, which can result in faulty connection.
5. Connect SST (check harness ºAº) between the ECM and
connector of the vehicle wire harness.
SST 09990±01000
HINT: The arrangement of the check connector terminals are
the same as those of the ECM.
See page EG±511.
6. Disconnect the SST.
SST 09990±01000
7. Reconnect the connector to the ECM.
(a) M a t c h t h e m a l e connector correctly with the female
connector, then press them together.
(b) Tighten the bolt.
Make sure the connector is completely connected by tighten-
ing the bolt until there is a clearance of less than 1 mm (0.04
in.) between the bottom of the male connector and the end
of the female connector.
8. Install the ECM protector and floor carpet. EG±510
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

STANDARD VALUE OF ECM TERMINALS
Always
IG switch ON
IG switch ON
IG switch ON and apply vacuum to the
throttle opener Throttle valve fully closed
IG switch ON
Main or sub±throttle valve fully closed
Idling, Intake air temp. 0°C (32°F) to 80°C
(176°F)
IG switch ON Throttle valve fully open
IG switch ON Sub±throttle valve fully closed
IG switch ON
Main or sub±throttle valve fully closed
IG switch ON Sub±throttle valve fully open
IG switch ON
Main or sub±throttle valve fully open
Idling, Engine coolant temp. 60°C (140°F) to
120°C (248°F)
Cranking
IG switch ON
Idling
IG switch ON
IG switch ON
Idling
Idling
Idling
Idling
Idling
IG switch ON
IG switch ON
IG switch ON
Pulse generation
Pulse generation
Pulse generation
Pulse generation
Pulse generation
Symbols (Terminals No.)STD Voltage (V)Condition
(See page EG±583)
(See page EG±521)
(See page EG±521)
(See page EG±517)
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±511