1986 TOYOTA SUPRA ignition

DTCCircuit
G, NE signal circuit (No.2)
Engine coolant temp. sensor
circuit
Intake air temp. sensor circuit
Throttle position sensor
circuit
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) 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) are output during the diagnostic trouble
code check, and inspection of the appropriate circuits reveals 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±387.
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 indi-
cates that the place where the wire harness, connector or ter-
minals being pulled or vibrated has a 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 thor-
oughly for faulty contacts, etc., then try the check again. If the
malfunction indicator lamp still does not go off, check and re-
place ECM.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±399

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

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

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

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 6 consecutive IGT
 
 
Open or short in IGF OR IGT circuit from igniter
to ECM
 
 
14 
 
No IGF signal to ECM for 6 consecutive IGT
signals 
 
to ECM

Igniter

ECM
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±413

INSPECTION PROCEDURE
(See page IN±30).
(See page EG±404)
Check for spark.
Disconnect the high±tension cord from the distributor, hold its end about 12.5 mm (1/2º) from
the ground, see if spark occurs while the engine is being cranked.
Spark should be generated.
To prevent excess fuel being injected from the injectors during this check. Don't crank the engine
for more than 1 Ð 2 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).
Disconnect igniter connector and check voltage between terminal IGF
of engine control module connector and body ground.
Repair or replace harness or connector.
Replace igniter.
Check and replace engine control module.
(1) Disconnect igniter connector.
(2) Connect SST (check harness ªAº).
See page EG±404)
SST 09990±01000
(3) Turn ignition switch ON.
Measure voltage between terminal IGF of engine
control module connector and body ground.
Voltage: 4.5 ~ 5.5 V EG±414
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

Connect SST (check harness ªAº).
See page EG±404)
SST 09990±01000
Measure voltage between terminal IGF 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)
Check voltage between terminal IGT of engine control module connector and
body ground.
INSPECTION USING OSCILLOSCOPE

During cranking or idling, check waveforms between
terminal IGT and E1 of engine control module.
HINT: The correct rectangular waveforms are as shown.
Check voltage between terminal 3 of igniter connector and body ground.
Disconnect igniter connector.
Measure voltage between terminal 3 of igniter
connector and body ground, when ignition switch
is turned to ªONº and ªSTARTº position.
Voltage: 9 Ð 14 V
Check and repair igniter power source circuit.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±415