1995 TOYOTA SUPRA ignition

(See page EG±510)
(1) Connect SST (check harness ªAº).
(See page EG±510)
(2) Turn ignition switch ON
Measure voltage between terminals THW and
E2 of engine control module connector.
Check voltage between terminals THW and E2 of engine control module
connector.
Check for intermittent problems.
(See page EG±505)
Disconnect the engine coolant temp. sensor con-
nector.
Measure resistance between terminals.
Resistance is within Acceptale Zone on chart.
Check engine coolant temp. sensor.
Replace engine coolant temp. sensor.
Repair or replace harness or connector.
Check and replace engine control module.
Check for open and short in harness and connector between engine control
module and engine coolant temp. sensor (See page IN±30).
INSPECTION PROCEDURE
HINT: If diagnostic trouble codes º22º (engine coolant temperature sensor circuit), º24º (intake air temperature
sensor circuit) and º41º (throttle position sensor circuit) are output simultaneously, E2 (sensor ground)
may be open.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±531

(See page EG±510)
(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Turn ignition switch ON
Measure voltage between terminals THW and E2
of engine control module connector.
Check voltage between terminals THA and E2 of engine control module
connector.
Check for intermittent problems.
(See page EG±505)
Disconnect the mass air flow meter connector.
Measure resistance between terminals 3 and 4
of mass air flow meter connector.
Resistance is within Acceptable Zone on chart.
Check intake air temp. sensor.
Check for open and short in harness and connector between engine
control module and intake air temp. sensor (See page IN±30)
Replace intake air temp. sensor (Replace
mass air flow meter).
Repair or replace harness or connector.
Check and replace engine control module.
INSPECTION PROCEDURE
HINT: If diagnostic trouble codes º22º (engine coolant temperature sensor circuit), º24º (intake air temperature
sensor circuit) and º41º (throttle position sensor circuit) are output simultaneously, E2 (sensor ground)
may be open.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±533

DTC 25 26 Air±Fuel Ratio Lean Rich Malfunction
CIRCUIT DESCRIPTION
See EG±525 for the circuit description.
 DTC No. Diagnostic Trouble Code Detecting Condition Trouble Area
 
 
 
 
 
 
 
 
 
 
 
 
 
 
(1) Main heated oxygen sensor voltage is
0.45 V or less (lean) for 90 sec. under
conditions (a) and (b):
(2 trip detection logic)*
2
(a) Engine coolant temp.: 70°C (158°F)
or more
(b) Engine speed: 1,500 rpm or more
 
 
 
 
 
 
 

Open or short in main heated oxygen
sensor circuit

Main heated oxygen sensor

Ignition system

ECM
 
 
 
 
 
 
 
 
25 
 
 
 
 
 
 
 
(2) Engine speed varies by more than 20 rpm
over the preceding crank angle period
during a period of 25 sec. or more under
conditions (a) and (b):
(2 trip detection logic).*
(a) Engine speed: Below 950 rpm
(b) Engine coolant temp.: 80°C
(176°F) or
more 
 
 
 
 
 
 
 

Open and short in injector circuit

Fuel line pressure (injector leak, blockage)

Mechanical system malfunction
(skipping teeth of timing belt)

Ignition system

Compression pressure (foreign object
caught in valve)

Mass air flow meter (air intake)

ECM
 
 
 
 
 
 
 
 
26
 
 
 
 
 
 
 
 
Engine speed varies by more than 20 rpm over
The preceding crank angle period during a
Period of 25 sec. or more under conditions (a)
And (b):
(2 trip detection logic).*
(a) Engine speed: Below 950 rpm
(b) Engine coolant temp.: 80°C
(176°F) or
more 
 
 
 
 
 
 
 

Open and short in injector circuit

Fuel line pressure (injector leak, blockage)

Mechanical system malfunction
(skipping teeth of timing belt)

Ignition system

Compression pressure (foreign object
caught in valve)

Mass air flow meter (air intake)

ECM
*: See page EG±503. EG±534
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

INSPECTION PROCEDURE
HINT: When other codes are output in addition to 27 at the same time, check the circuits for other codes first.
(See page EG±510)
(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Turn ignition switch ON.
Measure voltage between terminal HT2 of
engine control module connector and body
ground.
Voltage: 9 Ð 14 V
Check voltage between terminal HT2 of engine control module connector
and body ground.
EG±542± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(See page IN±30).
(See page EG±510)(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Start engine.
Measure voltage between terminals VG and E21 of
engine control module connector while engine rpm
at idling.
Voltage: 0.7 Ð 1.7 V
Check voltage between terminal 1 of mass air flow meter connector and
body ground.
Check voltage between terminals VG and E21 of engine control module
connector.
Check and replace engine control module
Check for open and short in harness and connector between engine
control module and mass air flow meter (See page IN±30).
Check and repair mass air flow meter power
source circuit.
Repair or replace harness or connector.
Replace mass air flow meter.
(1) Disconnect the mass air flow meter connector.
(2) Turn ignition switch ON.
Measure voltage between terminal 1 of mass air
flow meter connector and body ground.
Voltage: 9 Ð 14 V
INSPECTION PROCEDURE
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±545

(See page EG±510)
(1) Remove VSV.
(2) Disconnect VSV connector.
Check operation of VSV for waste gate valve when
battery positive voltage is applied and released to
the VSV terminals.
Battery positivie voltage is applied:
Air from port E is flowing out through port F.
Battery positive voltage is applied:
Closed air passage from E to F.
Check voltage terminals PMC of engine control module connector and
body ground.
Check operation of VSV for waste gate valve.
Replace VSV for waste gate valve.
Check and repair harness and connector be-
tween VSV for waste gate valve and engine
control module.
(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Turn ignition switch ON.
Measure voltage between terminals PMC of engine
control module and ground.
Voltage: 9 Ð 14 V
Check and replace enginie control module. EG±548
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(See page EG±510)(1) Connect SST (check harness ªAº).
(See page EG±510)
SST 09990±01000
(2) Turn ignition switch ON.
Measure voltage between terminals VCC and E1
of engine control module.
Voltage: 4.5 Ð 5.5 V
Check voltage between terminals VCC and E1 of engine control module
connector.
Check and replace engine control module.
INSPECTION PROCEDURE
HINT: DTC 35 indicates trouble in the BARO sensor circuit or turbo pressure sensor circuit. Because all func±
tions of the BARO sensor circuit are built into the ECM, it is not possible to check this circuit.
However, if no problem is found in the turbo pressure sensor circuit, it can be concluded that the problem
is in the BARO sensor circuit. EG±550
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

(See page IN±30).
Turn ignition switch ON.
Measure voltage between terminals PM1 and E2
of engine control module.
Voltage: 2.3 Ð 3.0 V
Check voltage between terminals PM1 and E2 of engine control module.
Check for open and short in harness and connector between engine control
module and turbo pressure sensor (See page
IN±30).
Check and replace engine control module.
Repair or replace harness or connector.
Replace turbo pressure sensor.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±551