LEXUS LS430 2003 Factory Repair Manual

c. Turn the ignition switch to the ON position.
d. Push the "ON" button of the hand-held tester.
e. Select the item "DIAGNOSIS/ENHANCED OBD II/DATA LIST".
f. According to the display on tester, read the "DATA LIST".
Fig. 78: Test Item Reference Chart

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1.INSPECT STOP LAMP SWITCH ASSY
a. Remove the stop lamp switch assy.
b. Measure the resistance according to the value(s) in the table below.
Fig. 79: Inspecting Stop Lamp Switch Assy

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Standard:
Fig. 80: Stop Lamp Switch Reference Chart

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NG: REPLACE STOP LAMP SWITCH ASSY
OK: Go to next step
2.CHECK HARNESS AND CONNECTOR (STOP LAMP SWITCH ASSY - ECM)
a. Install the stop lamp switch assy.
b. Measure the voltage according to the value(s) in the table below when the brake pedal is depressed
and released.

Fig. 81: Identifying ECM Connectors
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Standard:
Fig. 82: Stop Lamp Switch Reference Chart

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NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (See ELECTRONIC CIRCUIT
INSPECTION PROCEDURE )

OK: REPLACE ECM (See REPLACEMENT)
DTC P0729: GEAR 6 INCORRECT RATIO
SYSTEM DESCRIPTION
The ECM uses signals from the output speed sensor SP2 and input speed sensor NT to detect the actual gear
position (1st, 2nd, 3rd, 4th, 5th or 6th gear). Then the ECM compares the actual gear with the shift schedule in
the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic
transmission (clutch, brake or gear, etc.).
Fig. 83: Identifying Valve Body

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Fig. 84: DTC Reference Chart
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HINT:
Gear positions in the event of a solenoid valve mechanical problem:
Fig. 85: Gear Position Specification

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Gear position during fail-safe operation:
If any malfunction is detected, the ECM changes into the fail-safe mode to shift into the gear positions as shown
in the table below.
Fig. 86: Gear Position Specification

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MONITOR DESCRIPTION
The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF" and switching oil pressure to
the valves in the valve body.
The DTC indicates that the reverse sequence valve is locked in the direction the spring stretches and that
shifting to the 6th gear is impossible.
MONITOR STRATEGY
MONITOR STRATEGY TABLE
Related DTCsP0729: Gear 6 incorrect ratio (Reverse sequence
valve)/Rationality check
Require sensors/ComponentsReverse sequence valve
Frequency of operationContinuous
Duration0.4 sec.

TYPICAL ENABLING CONDITIONS
The following items are common to all conditions below.
TYPICAL ENABLING CONDITIONS TABLE
Condition (A)
TYPICAL ENABLING CONDITIONS TABLE - A
Condition (B)
TYPICAL ENABLING CONDITIONS TABLE - B
TYPICAL MALFUNCTION THRESHOLDS
MIL operation2 driving cycles
Sequence of operationNone
The monitor will run whenever this DTC is not
present.See LIST OF DISABLE A MONITOR
Turbine speed sensor circuitNot circuit malfunction
Output speed sensor circuitNot circuit malfunction
Shift solenoid valve S1 circuitNot circuit malfunction
Shift solenoid valve S2 circuitNot circuit malfunction
Shift solenoid valve S3 circuitNot circuit malfunction
Shift solenoid valve S4 circuitNot circuit malfunction
Shift solenoid valve SR circuitNot circuit malfunction
Shift solenoid valve SL1 circuitNot circuit malfunction
Shift solenoid valve SL2 circuitNot circuit malfunction
ECT (Engine coolant temperature) sensor circuitNot circuit malfunction
KCS sensor circuitNot circuit malfunction
ETCS (Electric throttle control system)Not system down
Transmission range"D"
ECT40°C (104°F) or more
Spark advance from Max. retard timing by KCS
control0° CA or more
EngineStarting
ECM selected gear5th
Vehicle speed2 km/h (1.2 mph) or more
Throttle valve opening angle6.5% or more (Varies with engine speed)
ECM selected gear6th
Vehicle speed2 km/h (1.2 mph) or more
Throttle valve opening angle6.5ohms or more (Varies with engine speed)

Both of the following conditions are met: Condition (A) and (B)
Condition (A)
TYPICAL MALFUNCTION THRESHOLDS TABLE - CONDITION A
Condition (B)
TYPICAL MALFUNCTION THRESHOLDS TABLE - CONDITION B
INSPECTION PROCEDURE
1.CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0729)
a. Connect the hand-held tester to the DLC3.
b. Turn the ignition switch to the ON position and push the hand-held tester main switch ON.
c. Select the item "DIAGNOSIS/ENHANCED OBD II/DTC INFO/CURRENT CODES".
d. Read the DTCs using the hand-held tester.
Result:
DTC OUTPUT RESULT TABLE
HINT:
If any other codes besides "P0729" are output, perform troubleshooting for those DTCs first.
B: GO TO RELEVANT DTC CHART (See DIAGNOSTIC TROUBLE CODE CHART
)
A: Go to next step
2.PERFORM ACTIVE TEST BY HAND-HELD TESTER
HINT:
Performing the ACTIVE TEST using the hand-held tester allows the relay, VSV, actuator and so on to
operate without parts removal. Performing the ACTIVE TEST as the first step of troubleshooting is one
method to shorten labor time.
It is possible to display the DATA LIST during the ACTIVE TEST.
Turbine speed/Output speed (NT/NO)0.66 to 0.8
Turbine speed/Output speed (NT/NO)0.93 to 1.07
Display (DTC output)Proceed to
Only "P0729" is outputA
"P0729" and other DTCsB

a. Warm up the engine.
b. Turn the ignition switch off.
c. Connect the hand-held tester together with the CAN VIM (controller area network vehicle interface
module) to the DLC3.
d. Turn the ignition switch to the ON position.
e. Push the "ON" button of the hand-held tester.
f. Clear the DTC.
g. Select the item "DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/SHIFT".
h. According to the display on tester, perform the "ACTIVE TEST".
HINT:
While driving, the shift position can be forcibly changed with the hand-held tester.
Comparing the shift position commanded by the ACTIVE TEST with the actual shift position enables
you to confirm the problem (see FAIL
-SAFE CHART ).
Fig. 87: Test Item Reference Chart

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HINT:
This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
The 4th to 5th and 5th to 6th up-shiftings must be performed with the accelerator pedal released.
The 6th to 5th and 5th to 4th down-shiftings must be performed with the accelerator pedal released.
Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift
successively.
The shift position commanded by the ECM is shown in the DATA LIST/SHIFT display on the
hand-held tester.
Gear positions in the event of a solenoid valve mechanical problem:
GEARSHIFT SPECIFICATION TABLE
Tester
command 1st2nd3rd4th5th6th

OK:
Gear position changes in accordance with the tester command
NG: REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSY (See step 6 on
REPLACEMENT
)
OK: Go to next step
3.CLEAR THE DTC AND RUNNING TEST
a. Clear the DTC, and check DTC again after conducting the "MONITOR DRIVE PATTERN FOR
ECT TEST" (see MONITOR DRIVE PATTERN
).
OK:
No DTC code
NG: REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSY (See step 6 on
REPLACEMENT
)
OK: END
DTC P0748: PRESSURE CONTROL SOLENOID "A" ELECTRICAL (SHIFT SOLENOID VALVE
SL1)
CIRCUIT DESCRIPTION
Shifting from 1st to 6th is performed in combination with "ON" and "OFF" operation of the shift solenoid
valves SL1, SL2, S1, S2, S3, S4 and SR which is controlled by the ECM. If an open or short circuit occurs in
either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the
vehicle to be operated smoothly (see FAIL
-SAFE CHART ).
Fig. 88: DTC Reference Chart

gearshift
Actual gear
position under
malfunction4th

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MONITOR DESCRIPTION
This DTC indicates an open or short in the shift solenoid valve SL1 circuit. The ECM commands gearshift by
turning the shift solenoid valves "ON/OFF". When there is an open or short circuit in any shift solenoid valve
circuit, the ECM detects the problem and illuminates the MIL and stores the DTC. And the ECM performs the
fail-safe function and turns the other shift solenoid valves in good condition "ON/OFF". (In case of an open or
short circuit, the ECM stops sending current to the circuit.)
While driving and shifting between 4th and 5th gears, if the ECM detects an open or short in the shift solenoid
valve SL1 circuit, the ECM determines there is a malfunction (see FAIL
-SAFE CHART ).
MONITOR STRATEGY
MONITOR STRATEGY TABLE
TYPICAL ENABLING CONDITIONS
TYPICAL ENABLING CONDITIONS TABLE
Condition (A)
TYPICAL ENABLING CONDITIONS TABLE - A
Condition (B)
TYPICAL ENABLING CONDITIONS TABLE - B
TYPICAL MALFUNCTION THRESHOLDS
Related DTCsP0748: Shift solenoid valve SL1/Range check
Required sensors/ComponentsShift solenoid valve SL1
Frequency of operationContinuous
Duration1 sec.
MIL operationImmediate
Sequence of operationNone
The monitor will run whenever this DTC is not
present.See LIST OF DISABLE A MONITOR
Battery voltage10 V or more and less than 12V
CPU commanded duty ratio to SL1Less than 75%
Ignition SwitchON
StarterOFF
Battery voltage12 V or more
Ignition SwitchON
StarterOFF