1995 TOYOTA SUPRA relay

ECM Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned on, battery
voltage is applied to the terminals IGSW of the
ECM, and the main relay control circuit in the
ECM sends a signal to the terminal M±REL of the
ECM, switching on the main relay. This signal
causes current to flow to the coil, closing the con-
tacts of the main relay and supplying power to the
terminal +B of the ECM.
If the ignition switch is turned off, the ECM contin-
ues to switch on the main relay for a maximum of
2 seconds for the initial setting of the IAC valve.
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±465

Check EFI main relay.
Remove EFI main relay from R/B No.2.
Check continuity between terminals of EFI main
relay shown below.
Replace EFI main relay.
(1) Apply battery voltage between terminals 1
and 2.
(2) Check continuity between terminals 3 and 5.
Repair or replace harness or connector.
Check and repair harness or connector between
EFI No.1 fuse and battery.
Check for open and short in harness and connector between terminal M±REL
of engine control module and body ground(See page
IN±30).
Terminals 3 and 5
Terminals 3 and 5
Terminals 1 and 2
Open
Continuity
Continuity
(Reference value 72
)
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±469

INSPECTION PROCEDURE
Check IAC valve.
Disconnect IAC valve connector.
Measure resistance between terminals shown be-
low.
Replace IAC valve.
Remove IAC valve.
(1) Connect the battery positive lead to terminals 5
(B1) and 2 (B2), and the negative lead to termi±
nals 4(S1)Ð1(S2)Ð6(S3)Ð3(S4) in that order.
(2) Connect the battery positive lead to terminals 5
(B1) and 2 (B2), and the negative lead to termi±
nals 3(S4)Ð6(S3)Ð1(S2)Ð4(S1) in that order.
(1) The valve moves in the closing direction.
(1) The valve moves in the opening direction.
Check for open and short in harness and connector between EFI main relay
and IAC valve, IAC valve and engine control module(See page
IN±30).
Repair or replace harness or connector.
Proceed to next circuit inspection shown on matrix
chart (See page
EG±408).
TerminalResistance
± ENGINE2JZ±GE ENGINE TROUBLESHOOTINGEG±477

(See page EG±404)
(See page EG±230)
Check voltage between terminal ACIS of engine control module connector
and body ground.
(1) Connect SST (check harness ªAº).
(See page EG±404)
SST 09990±01000
(2) Turn ignition switch ON.
Measure voltage between terminal ACIS of en-
gine control module connector and body ground.
Voltage: 9 Ð 14 V
Check for vacuum tank. (See page EG±230)
Repair or replace harness or connector.
Check and replace engine control module.
Check for open and short in harness and connector between EFI main relay
and engine control module (See page
IN±30).
EG±480± ENGINE2JZ±GE ENGINE TROUBLESHOOTING

(See page EG±404)
Check voltage between terminal FPU of engine control module connector
and body ground.
(1) Connect SST (check harness ªAº).
(See page EG±404)
SST 09990±01000
(2) Turn ignition switch ON.
Measure voltage between terminal FPU of engine
control module connector and body ground.
Voltage: 9 Ð 14 V
Proceed to next circuit inspection shown on
matrix chart (See page EG±408).
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 VSV, VSV and EFI main relay (See page
IN±30).
± ENGINE2JZ±GE ENGINE TROUBLESHOOTING7EG±483

 
 
 Trouble Area
 
 
 
Malfunction
Indicator
Lamp*
1
 
 
 Memory*2
 
 
 See page
 
 
Trouble Area
 
 
Normal
Mode 
 
Test
Mode 
 
Memory
 
 
See page
 
 
 

Open or short in throttle position sensor circuit

Throttle position sensor

ECM
 
 
 
ON
 
 
 
ON
 
 
 

 
 
 
EG±552
 
 
 
 
 
 
 
 
 

No.1 vehicle speed sensor

Telltale light RH

Open or short in No.1 vehicle speed sensor circuit

ECM
 
 
 
 
 
 
 
 
 
OFF
 
 
 
 
 
 
 
 
 
OFF
 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 
 
 
EG±556
 
 
 

Open or short in starter signal circuit

Open or short in ignition switch or starter relay circuit

ECM
 
 
 
N.A
 
 
 
OFF
 
 
 
X
 
 
 
EG±559
 
 
 

Open or short sub±throttle position sensor circuit

Sub±throttle position sensor

ECM
 
 
 
OFF
 
 
 
ON
 
 
 

 
 
 
EG±552
 
 
 

Open or short in No.1 knock sensor circuit

No.1 Knock sensor (loosensess)

ECM
 
 
 
ON
 
 
 
N.A
 
 
 

 
 
 
EG±561
 
 
 

ECM
 
 
 
ON
 
 
 
N.A
 
 
 
X
 
 
 
EG±561
 
 
 

Open or short in No.2 knock sensor circuit

No.2 Knock sensor (looseness)

ECM
 
 
 
ON
 
 
 
N.A
 
 
 

 
 
 
EG±561
*1,
2: See page EG±502.
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTINGEG±501

Suspect area
See page
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 not
start
Difficult to
start
Poor Idling
Engine Stall
Poor
Driveability
Back up power source circuitECM power source circuitPark/neutral position switch circuitSwitch condition signal circuitEGR systemStarter signal circuitMass air flow meter circuitInjector circuitIAC valve circuitFuel pump control circuitA/C signal circuit (Compressor circuit)Turbo control circuitVSV circuit for fuel Pressure ControlCompressionSpark plugIgnition signal circuit (Spark test)Starter and Starter relayIgnition coilEngine control module (ECM)Theft deterrent ECUA/T faulty
EG±544EG±559EG±564EG±571EG±574EG±576EG±581EG±583EG±586EG±568EG±595EG±589AC±62ST±3
,
12
IG±21IG±23IG±22EG±9AT2±101BE±123IN±35
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±514
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING

Disconnect main heated oxygen sensor connector.
Measure resistance between terminals 1 and 2 of
main heated oxygen sensor connector.
Resistance: 11 Ð 16
at 20°C (68°F)
Check main heated oxygen sensor heater.
Replace main heated oxygen sensor.
Check and repair harness or connector between
main relay and main heated oxygen sensor, main
heated oxygen sensor and engine control module.
Warm up engine to normal operating temperature.
Measure voltage between terminals HT1 of engine
control module connector and body ground, when
engine is idling and racing at 4,000 rpm.
Check voltage between terminals HT1 of engine control module connector
and body ground.
Replace main heated oxygen sensor.*
Check and replace engine control module.
In the 4,000 rpm racing check, continue engine
racing at 4,000 rpm for approx. 20 seconds or
more.
*: It is probable the oxygen sensor has deteri±
orated. Usually, this cannot be confirmed by
visual inspection. EG±528
± ENGINE2JZ±GTE ENGINE TROUBLESHOOTING