1986 TOYOTA SUPRA Service Repair Manual

2JZ±GE ENGINE TROUBLESHOOTING
EG±381

P. EG±783
P. EG±785, P. EG±387
P. EG±386
P. IN±24
P. EG±386
P. EG±400P. EG±388
P. EG±408
P. EG±409
P. EG±399
Vehicle Brought to Workshop
Customer Problem Analysis
Check and Clear Diagnostic Trouble Code (Precheck)
Setting the Test Mode Diagnosis
Problem Symptom Confirmation
Malfunction does not occur.
Malfunction
occur.Symptom Simulation
Diagnostic Trouble Code Check
Malfunction codeNormal code
Basic Inspection
Matrix chart of Problem Symptoms
Circuit Inspection
Parts Inspection
Confirmation Test
Adjustment, Repair
Identification of Problem
Step [2], [3], [6], [11], [14]: Diagnostic steps permitting the use of
the TOYOTA hand±held tester
or TOYOTA break±out±box.
Titles insideare titles of pages
in this manual, with the page number
indicated in the bottom portion.
See the indicated pages for detailed
explanations.
Diagnostic Trouble Code Chart
Check for intermittent problems
HOW TO PROCEED WITH TROUBLESHOOTING
Troubleshoot in accordance with the procedure on the following pages. EG±382
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

CUSTOMER PROBLEM ANALYSIS CHECK SHEET
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±383

DIAGNOSIS SYSTEM
DESCRIPTION
The ECM contains a built±in self±diagnosis system by which
troubles with the engine signal network are detected and a Mal-
function Indicator Lamp on the instrument panel lights up.
By analyzing various signals as shown in a later table (See page
EG±388) the Engine Control Module (ECM) detects system mal-
functions relating to the sensors or actuators.
In the normal mode, the self±diagnosis system monitors 18
(California specification vehicles) or 17 (except for California and
Canadian specification) items, indicated by code No. as shown in
EG±388. A malfunction indicator lamp informs the driver that a
malfunction has been detected. The lamp goes off automatically
when the malfunction has been repaired, but the diagnostic
trouble code(s) remains stored in the ECM memory (except for
code Nos. 16 and 53). The ECM stores the code(s) until it is
cleared by removing the EFI No. 1 fuse with the ignition switch
OFF.
The diagnostic trouble code can be read by the number of blinks
of the malfunction indicator lamp when TE1 and E1 terminals on
the data link connector 1 or 2 are connected. When 2 or more
codes are indicated, the lowest number (code) will appear first.
In the test mode, 12 (California specification vehicles) or 11 (ex-
cept for California and Canadian specification vehicles) items, in-
dicated by code No. as shown in EG±388 are monitored. If a mal-
function is detected in any one of the systems indicated by code
Nos. 13, 21, 22, 24, 25, 26, 27, 28, 35, 41, 71 and 78 (California
specification vehicles) or 13, 21, 22, 24, 25, 28, 35, 41, 71 and 78
(except for California and Canadian specification vehicles) the
ECM lights the malfunction indicator lamp to warn the technician
that a malfunction has been detected. In this case, TE2 and E1
terminals on the data link connector 2 should be connected as
shown later. (See page EG±386).
In the test mode, even if the malfunction is corrected, the malfunc-
tion code is stored in the ECM memory even when the ignition
switch OFF (except code Nos. 43 and 51). This also applies in the
normal mode. The diagnostic trouble mode (normal or test) and
the output of the malfunction indicator lamp can be selected by
connecting the TE1, TE2 and E1 terminals on the data link con-
nector 2, as shown later.
A test mode function has been added to the functions of the self±
diagnosis system of the normal mode for the purpose of detecting
malfunctions such as poor contact, which are difficult to detect in
the normal mode. This function fills up the self±diagnosis system.
The test mode can be implemented by the technician following the
appropriate procedures of check terminal connection and opera-
tion described later. (See page EG±386) EG±384
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

Diagnosis Inspection (Normal Mode)
MALFUNCTION INDICATOR LAMP
CHECK
1. The Malfunction Indicator Lamp will come on when the
ignition switch is turned ON and the engine is not running.
HINT: If the malfunction indicator lamp does not light up, pro-
ceed to troubleshooting of the telltale light RH
(See page BE±48).
2. When the engine is started, the malfunction indicator lamp
should go off.
If the light remains on, the diagnosis system has detected a
malfunction or abnormality in the system.
DIAGNOSTIC TROUBLE CODE CHECK
1. Turn ignition switch ON.
2. Using SST, connect terminals between TE1 and E1 of data
link connector 1 or 2.
SST 09843±18020
3. Read the diagnostic trouble code from malfunction indicator
lamp.
HINT: If a diagnostic trouble code is not output, check the TE1
terminal circuit (See page EG±484).
As an example, the blinking patterns for codes; normal, 12
and 31 are as shown on the illustration.
4. Check the details of the malfunction using the diagnostic
trouble code table on page EG±388.
5. After completing the check, disconnect terminals TE1 and
E1, and turn off the display.
HINT: In the event of 2 or more malfunction codes, indication
will begin from the smaller numbered code and continue in
order to the larger.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±385

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±484.
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±385).
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±386
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

DIAGNOSTIC TROUBLE CODE CHECK
USING TOYOTA HAND±HELD TESTER
1. Hook up the TOYOTA hand±held tester to the DLC2.
2. Read the diagnostic trouble codes by following the prompts
on the tester screen.
Please refer to the TOYOTA hand±held tester operation's
manual for further details.
DIAGNOSTIC TROUBLE CODE CLEARANCE
1. After repair of the trouble areas, the diagnostic trouble code
retained in the ECM memory must be cleared out by
removing the EFI No.1 fuse (30A) from R/B No.2 for 10
seconds or more, with the ignition switch OFF.
HINT:
wCancellation can also be done by removing the negative
(±) terminal cable from the battery, but in this case, other
memory systems (clock, etc.) will also be cancelled out.
wIf it is necessary to work on engine components
requiring removal of the negative (±) terminal cable from
the battery, a check must first be made to see if a
diagnostic trouble code has been recorded.
2. After cancellation, road test the vehicle to check that a normal
code is now read on the malfunction indicator lamp.
If the same diagnostic trouble code appears, it indicates that
the trouble area has not been repaired thoroughly.
ECM DATA MONITOR USING TOYOTA
HAND±HELD TESTER
1. Hook up the TOYOTA hand±held tester to the DLC2.
2. Monitor the ECM data by following the prompts on the tester
screen.
HINT: TOYOTA hand±held tester has a ºSnapshotº function which
records the monitored data.
Please refer to TOYOTA hand±held tester operator's manual for
further details.
ECM TERMINAL VALUES MEASUREMENT
USING TOYOTA BREAK±OUT±BOX AND
TOYOTA HAND±HELD TESTER
1. Hook up the TOYOTA break±out±box and TOYOTA
handheld tester to the vehicle.
2. Read the ECM input/output values by following the prompts
on the tester screen.
HINT: TOYOTA hand±held tester has a ºSnapshotº function. This
records the measured values and is effective in the diagnosis of
intermittent problems.
Please refer to TOYOTA hand±held tester/TOYOTA break±out
box operator's manual for further details.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±387

DIAGNOSTIC TROUBLE CODE CHART
HINT: Parameters listed in the chart may not be exactly the same as your reading due to type of the instruments
or other factors.
~
DTC
No.Number of
MIL BlinksCircuitDiagnostic Trouble Code Detecting Condition
NormalNo code is recorded.
G, NE Signal
(No.1)
G, NE Signal
(No.2)
Ignition Signal
A/T Control
Signal
(Main heated *3)
Oxygen
Sensor Signal
(Fr)
No NE or G1 and G2 signal to ECM for 2 sec. or more after cranking
Open in ªG
º circuit
No NE signal to ECM for 0.1 sec. or more at 1,000 rpm or more
NE signal does not pulse 12 times to ECM during the interval between
G1 and G2 pulses
No IGF signal to ECM for 6 consecutive IGT signals
Fault in communications between the engine CPU and A/T CPU in the
ECM
(1)*3Open or short in heater circuit of main heated oxygen sensor (Fr)
for 0.5 sec. or more
(2) (Main heated*3) oxygen sensor (Fr) signal voltage is reduced to
between 0.35 V and 0.70 V for 90 sec. under conditions
(a) ~ (d):
(2 trip detection logic)*4
(a) Engine coolant temp.: Between 80°C (176°F) and
95°C (203°F)
(b) Engine speed: 1,500 rpm or more
(c) Load driving (example A/T in in Overdrive, (5th for M/T),
A/C ON, Flat road, 80 km/H (50 mph))
(d) (Main heated*
3) oxygen sensor (Fr) signal voltage:
Alternating above and below 0.45 V
*3, 4: See page EG±396, 397. EG±388
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING