TOYOTA SUPRA 1995 Service Repair Manual

PARTS LOCATION
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±403

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±253)
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±405.
6. Disconnect the SST.
SST 09990±01000
7. Reconnect the connector to the ECM.
(a) Match the male connector correctly with the female
connector, then press them together.
(b) Tighten the bolt.
Make sure the connector is completely connected by
tightening the bolt until there is a clearance of less than
1 mm (0.04 in.) between the bottom of the male connec-
tor and the end of the female connector.
8. Install the ECM protector and floor carpet. EG±404
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

(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

 Symbols (Terminals No.) STD Voltage (V) Condition
 ACIS (B39)±E01 (B80) 9 ~ 14 IG switch ON
 EVAP (B74)±E01 (B80) 9 ~ 14 IG switch ON 
 EGR (B75) E01 (B80)
 
 Below 2.0
 
 Idling
 EGR (B75)±E01 (B80) 9 ~ 14 Engine speed at 3,500 rpm
 
 
ISC1 (B35), ISC2 (B34)
±E01 (B80)
ISC3 (B33), ISC4 (B32) 
 Pulse generation
(See page EG±475) 
 Idling, when A/C switch ON or OFF
 
 
  VF1 (B29), VF2 (B28)±E1 (B69)
 
 
 1.8 ~ 3.2
 
 
 
Maintain engine speed at 2,500 rpm for 2
minutes after warming up then return to
Idling
 
  OX1 (B48), OX2 (B47)±E1 (B69)
OX3 (A30)* 
 Pulse generation
(See page EG±423) 
 Maintain engine speed at 2,500 rpm for 2
minutes after warming up
 
  HT1 (B73)*, HT2 (B72)*±E01 (B80)
 
 Below 3.0
 
 Idling
 
HT1 (B73) , HT2 (B72) E01 (B80)
HT3 (A36)* 9 ~ 14 IG switch ON
 
 KNK1 (B50), KNK2 (B49)±E1 (B69) 
 
Pulse generation
(See page EG±452) 
 Idling
 
 
NSW (B76) E1 (B69)
 
 9 ~ 14
 
 
IG switch ON
Other shift position in ºPº, ºNº position
 
 
NSW (B76)±E1 (B69) 
 0 ~ 3.0
 
 IG switch ON
Shift position in ºPº, ºNº position
 
 SP1 (A2)±E1 (B69)
 
 Pulse generation
(See page EG±445) 
 IG switch ON
Rotate driving wheel slowly
 
 TE1 (A20)±E1 (B69)
 
 9 ~ 14
 
 IG switch ON
 TE2 (A19)±E1 (B69) 9 ~ 14 IG switch ON
 
W (A6) E1 (B69)
 9 ~ 14 Idling
 W (A6)±E1 (B69) 0 ~ 3.0 IG switch ON 
 OD1 (A12)±E1 (B69) 
 9 ~ 14 
 IG switch ON
 A/C (A34) E1 (B69) 7.5 ~ 14 A/C switch OFF
 A/C (A34)±E1 (B69) 0 ~ 1.5 A/C switch ON (At idling)
 
ACMG (A23) E1 (B69)
 0 ~ 3.0 A/C switch ON (At idling) 
 
ACMG (A23)±E1 (B69) 
 9 ~ 14 
 A/C switch OFF
 FPU (B36)*E01 (B80) 9 ~ 14 IG switch ON
 FPU (B36)*±E01 (B80) Below 2.0 Restarting at high engine coolant temp.
 
ELS (A15) E1 (B69)
 7.5 ~ 14 Defogger switch and taillight switch ON 
 
ELS (A15)±E1 (B69) 
 0 ~ 1.5 
 Defogger switch and taillight switch OFF
*: Only for California specification vehicles EG±406
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

REFERENCE VALUE OF ECM DATA
HINT: ECM data can be monitored by TOYOTA hand±held
tester.
1. Hook up the TOYOTA hand±held tester to DLC2.
2. Monitor ECM data by following the prompts on the tester
screen.
Please refer to the TOYOTA hand±held tester operator's manual
for further details.
REFERENCE VALUE
 Item Inspection condition Reference value
 
 INJECTOR 
 
Engine cold to hot
Engine idling at normal operating temp.*1
 
 
Gradually decreases
Approx. 2.0 msec.
 IGNITION Increase engine speed Gradually increases
 
 
 
IAC STEP #
 
 
 
Engine idling at normal operating temp.*1
A/C switch ON
A/T shifting in ºDº position
Ignition switch ON (Engine off)
 
 
 
20 ~ 25 steps
Step increases
Step increases
Approx. 125 steps
 ENGINE SPEED RPM kept stable (Comparison with tachometer) No great changes 
 VA F
 
 Engine idling at normal operating temp.*1
Increase engine speed
 
 Approx. 35 ms
Gradually decreases
 ECT Engine at normal operating temp. 75±95°C (185±203°F)*2
 
 
 
THROTTLE
 
 
 
Closed throttle position
Wide open throttle
From closed throttle position to wide open throttle 
 
 
Below 5°
Above 70°
Gradually increases
 
 VEHICLE SPD 
 
During driving
(Comparison with speedometer) 
  No large differences
 TARGET A/FL*5 Engine idling at normal operating temp. 2.50 + 1.25 V*3
 TARGET A/FR*6 Engine idling at normal operating temp. 2.50 + 1.25 V*3
 A/F FB LEFT*5 RPM stable at 2500 rpm with normal operating temp. ON
 A/F FB RIGHT*6 RPM stable at 2500 rpm with normal operating temp. ON
 KNOCK FB Depress throttle pedal suddenly during idling ON
 STA SIGNAL During cranking ON
 CTP SIGNAL Closed throttle position ON
 A/C SIGNAL A/C switch ON ON
 PNP SIGNAL*4 When shifting from ºPº or ºNº position into a position
other than ºPº or ºNº GEAR
 O X L*5 RPM stable at 2500 rpm with normal operating temp. RICH LEAN is repeated O X R*6 RPM stable at 2500 rpm with normal operating temp. RICH LEAN is repeated
*1: If the engine coolant temp. sensor circuit is open or shorted, the ECM assumes an engine coolant temp.
value of 80
°C (176°F).
*
2: When feedback control is forbidden, 0 V is displayed.
*
3: A/T only
*
4: Oxygen sensor (Front)
*
5: Oxygen sensor (Rear)
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±407

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

CIRCUIT INSPECTION
DTC 12 G NE Signal Circuit (No.1)
CIRCUIT DESCRIPTION
The distributor in the Engine Control System contains 3 pick±up coils (G1, G2 and NE).
The G1, G2 signals inform the ECM of the standard crankshaft angle.
The NE signals inform the ECM of the crankshaft angle and the engine speed.
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble Area 
 
 12
 
 
 
No ºNEº or ºG1º and ºG2º signal to ECM for
2 sec. or more after cranking
 
 
 

Open or short in NE, G circuit

Distributor

Open or short in STA circuit 
12
 Open in ºG
ª circuit 
Open or short in STA circuit

ECM
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±409

INSPECTION PROCEDURE
Check resistance of each pickup coils in distributor.
INSPECTION USING OSCILLOSCOPE
Replace Distributor
Repair or replace harness or connector
Check for open and short in harness and connector between engine control
module and distributor (See page IN±30).
Disconnect distributor connector.
Measure resistance between each terminal shown
in the table below.
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).
wDuring cranking or idling, check waveforms between
terminals G1, G2, NE and G
of engine control
module
HINT: The correct waveforms are as shown.
G1 pickup coil
G2 pickup coil
NE pickup coil
(NE±G
)
(G1±G
)
(G2±G
)
Resistance
EG±410± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

Check air gap.
Remove distributor cap & rotor.
Using SST (G1 and G2 pickups) and a thickness gauge
(NE pickup), measure the air gap between the signal ro-
tor and pickup coil projection.
SST 09240±00020 for G1 and G2 pickups
Air gap: 0.2 Ð 0.5 mm (0.008 Ð 0.020 in.)
Replace distributor housing assembly
Check and replace engine control module.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±411

DTC 13 G NE Signal Circuit (No.2)
CIRCUIT DESCRIPTION
See G, NE signal circuit (No. 1) on page EG±409.
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble Area 
 
13
 
  No NE signal to ECM for 0.1 sec. or more at
1,000 rpm or more 
 
Open or short in NE circuit

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

Distributor

ECM
DIAGNOSIS
This code indicates that a intermittent problems of the G, NE signal from the distributor to the ECM has occurred,
but that it has returned to normal. Note that although this problem may not necessarily appear at the time of
inspection, it cannot be ignored because this diagnostic trouble code is output, indicating that there is or was
a malfunction in the G, NE signal circuit; this ºmalfunctionº is usually a loose connector.
The distributor connector and the NE terminal of the ECM connector must therefore be checked for the following:
1. Loose connectors
2. Dirty connector terminals
3. Loose connector terminals EG±412
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING