ignition LEXUS SC300 1991 Service Repair Manual

OKNG
OKNG
INSPECTION PROCEDURE
1Check output condition of diag. code 51.
C
OK
Hint
PSetting the test mode.
(2) Turn ignition switch OFF.
(2) Connect terminals TE2 and E1 and TDCL.
(2) Turn ignition switch ON.(For checking terminal A/C, start the engine.)
(2) Connect terminals TE1 and E1 of TDCL.
Check if code ª51º is output by the ªCHECKº engine
warning light.
*: Before the STA signal is input (ST is not ON), diagnostic code 43 is also output.
Diag. code 42 is output with vehicle speed 5 km/h (3
mph) or below
IDL1 .... Go to step 2 NSW ... Go to page TR±22.
A/C ..... Go to step 3
Proceed to next circuit inspection shown on
maxtrix chart (See page TR±35).
2Check throttle position sensor.
C
OK
PDisconnect throttle position sensor connector.
Measure resistance between terminals IDL1 and E2 of
throttle position sensor connector.
Adjust or replace throttle position sensor
See page FI±73).
Check and repair harness or connector between
engine & ECT ECU and throttle position sensor.
TR±120±
ENGINE TROUBLESHOOTING Circuit Inspection
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NGOK
OKNG
3Disconnect A/C control assembly connector, check voltage between terminal MGC of A/C con-
trol assembly connector and body ground.
C
OK
P(2) Remove air conditioner control assembly.
(2) Disconnect air conditioner control assembly con-
nector.
(2) Turn ignition switch on.
Measure voltage between terminal MGC of air condi-
tioner control assembly connector and body ground.
Voltage: 10 ± 14 V
Check and replace A/C control assembly.
4Check for open and short in harness and connector between engine & ECT ECU and\
A/C control
assembly (See page IN±27)
Repair or replace harness or connector.
Check and replace engine & ECT ECU.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±121
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ECU Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned on, battery voltage
is applied to the terminal IGSW of the ECU, and the
main relay control circuit in the ECU sends a signal to
the terminal M±REL of the ECU, switching on the
main relay. This signal causes current to flow to the
coil, closing the contacts of the main relay and supply-
ing power to the terminals +B and +B1 of the ECU.
If the ignition switch is turned off, the ECU continues
to switch on the main relay for a maximum of 2 se-
conds for the initial setting of the ISC valve.
DIAGNOSTIC CHART
See next page for the DIAGNOSTIC CHART.
WIRING DIAGRAM
TR±120±
ENGINE TROUBLESHOOTING Circuit Inspection
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Check voltage of ECU power source.
Check continuity between terminals E1 and
body ground.
Check voltage of terminal IGSW.
Check IGN fuse.
Check ignition switch.
Check for open in harness and connector
between battery and ECU.
Check voltage of terminal M±REL.
Check EFI fuse.
Check EFI main relay.Check for open and short in harness and
connector between terminal M±REL and
body ground.
Check and repair harness or connector
between EFI fuse and battery.
Repair or replace harness or
connector.
Replace EFI main relay.
Check for short in all the harness
and components connected to the
EFI fuse.
Check and replace ECU.
Replace ignition switch.
Check for short in all the harness and
components connected to IGN fuse.
Repair or replace harness or
connector.
Proceed to next circuit inspection
shown on matrix cart (See page
TR±39
).
DIAGNOSTIC CHART
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±121
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NGOK
OKNG
NGOK
INSPECTION PROCEDURE
1Check voltage between terminals +B, +B1 and E1 of engine (& ECT) ECU connec\
tor.
C
OK
P1. Connect the Check Harness A. (See page TR±34)
2. Turn ignition switch on.
Measure voltage between terminals +B, +B1 and E1
of engine (& ECT) ECU connector.
Voltage: 10 ± 14 V
Proceed to next circuit inspection shown on matrix chart
(See page TR±39).
2Check for open in harness and connector between terminal E1 of engine (\
& ECT) ECU and
body ground. (See page IN±27).
Repair or replace harness or connector.
3Check voltage between terminal IGSW of engine (& ECT) ECU connector an\
d body ground.
C
OK
PTurn ignition switch on.
Measure voltage between terminal IGSW of engine
(& ECT) ECU connector and body ground.
Voltage: 10 ± 14 V
Go to step
.
TR±122
±
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OKNG
OKNG
4Check IGN fuse.
C
OK
PRemove IGN fuse from J/B No. 1.
Check continuity of IGN fuse.
Continuity
Check for short in all the harness and components con-
nected to IGN fuse (See attached wiring diagram).
5Check ignition switch.
C
OK
PRemove under cover and finish panel.
Check continuity between terminals.
Replace ignition switch.
Check and repair harness and connector between
battery and ignition switch, ignition switch and en-
gine (& ECT) ECU.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±123
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OKNG
OKNG
6Check voltage between terminal M±REL of engine (& ECT) ECU connector and\
body ground.
C
OK
PTurn ignition switch on.
Measure voltage between terminal M±REL of engine
(& ECT) ECU connector and body ground.
Voltage: 10 ± 14 V
Check and replace engine (& ECT) ECU.
7Check EFI fuse.
C
OK
PRemove EFI fuse from R/B No. 2.
Check continuity of EFI fuse.
Continuity
Check for short in all the harness and components
connected to EFI fuse (See attached wiring diagram).
TR±124
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OK
NG
Type I
NG
Type II
NG
OK
OKNG
INSPECTION PROCEDURE
1Check output condition of diag. code 51.
C
P(2) Connect terminals TE2 and E1 of TDCL.
(2) Turn ignition switch on.
(2) Crank the engine.
(2) Connect terminal TE1 and E1 of TDCL.
Check if diagnostic code ª51º is output when then shift
level is in the P and D shift positions.
Result:
Go to step 2.
Go to step 3.
Proceed to next circuit inspection shown on ma-
trix chart (See page TR±35).
2
Check for open in harness and connector between engine & ECT ECU and neutral \
start switch
(See page IN±27).
Check and replace engine & ECT ECU.
Repair or replace harness or connector.
3Check neutral start switch (See page AT±100).
Replace neutral start switch.
Check and replace engine & ECT ECU.
±
ENGINE TROUBLESHOOTING Circuit InspectionTR±123
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 10 of 12
Procedure C:
a. Turn the ignition switch ON.
b. Measure the voltage between terminals TSR (+) and CLTE (±)
of the connector under the
following conditions:
Cover the sensor with a cloth
to avoid direct light.
Expose the sensor to light
from a distance of 300 mm
(11.81 in.) or less with an
inspection light.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incandes\
cent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
c. Measure the voltage between
terminals TSL (+) and CLTE (±)
of the connector under the
following conditions:
Cover the sensor with a cloth
to avoid direct light.
Expose the sensor to light
from a distance of 300 mm
(11.81 in.) or less with an
inspection light.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incand\
escent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
InspectionProcedure
(Continued)
CLTE
TSR
TSL
CLTE
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SENSOR INSPECTION FOR AIR CONDITIONING SYSTEM ± AC005-04 December 16, 2004
Page 11 of 12
Procedure D:
a. Turn the ignition switch ON.
b. Using the tester, measure the voltage between terminals
TSD (+) and CLTE (±) of the
connector under the
following conditions:
Cover the sensor with a cloth
to avoid direct light.
Expose the sensor to light
from a distance of 300 mm
(11.81 in.) or less with an
inspection light.
HINT:
If the light is weak, the sensor may not react. Be sure to use an incandes\
cent light
for an inspection light.
Do not disconnect the solar sensor connector.
Standard:
CONDITIONSPECIFICATION
When the sensor is covered with a cloth
(to avoid direct light)Below 0.8 V
When the sensor is exposed to light4.3 +/± 0.3 V
InspectionProcedure
(Continued)
TSD
CLTE
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