2003 LEXUS LS430 Identifying ac

Fig. 79: Identifying M4 And C12 Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE COMBINATION METER ASSY (SEE OVERHAUL
)
WIRING DIAGRAM
Fig. 80: ODO/TRIP Switch Wiring Diagram

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INSPECTION PROCEDURE
1.READ VALUE OF HAND-HELD TESTER
a. Operate the hand-held tester according to the steps on the display and select the "DATA LIST".
METER:
DATA LIST REFERENCE
ItemMeasurement Item/ Range (Display)Normal ConditionDiagnostic Note
ODO/TRIP SWODO/TRIP switch is ON / OFFON: Switch is pushed
OFF: Switch is released-
TRIP RESET SWTRIP RESET switch is ON / OFFON: Switch is pushed
OFF: Switch is released-

Fig. 81: Identifying Trip Switch Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: GO TO NEXT STEP
3.CHECK HARNESS AND CONNECTOR (TRIP SWITCH - COMBINATION METER ASSY)
(SEE HOW TO PROCEED WITH TROUBLESHOOTING
)
a. Disconnect the C12 and T10 connectors.
b. Measure the resistance according to the value (s) in the table below.
Standard
C12 AND T10 CONNECTORS RESISTANCE SPECIFICATIONS
Tester ConnectionConditionSpecified Condition
C12-7 - T10-1AlwaysBelow 1 ohms
C12-8 - T10-3AlwaysBelow 1 ohms
C12-10 - T10-2AlwaysBelow 1 ohms
C12-7 - Body groundAlways10 kohms or higher
C12-8 - Body groundAlways10 kohms or higher
C12-10 - Body groundAlways10 kohms or higher

Fig. 82: Identifying C12 And T10 Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE COMBINATION METER ASSY (SEE OVERHAUL
)
WIRING DIAGRAM
Fig. 83: Light Control Rheostat Wiring Diagram

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
INSPECTION PROCEDURE
1.READ VALUE OF HAND-HELD TESTER (LIGHT RHEOSTAT SIGNAL)
a. Operate the hand-held tester according to the steps on the display and select the "DATA LIST".
METER:
DATA LIST REFERENCE
ItemMeasurement Item/ Range
(Display)Normal ConditionDiagnostic
Note
LIGHT
RHEOSTATLight control rheostat / Min.: 0,
Max.: 255Light control rheostat switch is Dark
(0) --> Bright (255)-

Fig. 84: Identifying Light Control Rheostat Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: GO TO NEXT STEP
4.REPLACE DRIVER SIDE JUNCTION BLOCK
OK:
Normal operation
NG: REPLACE COMBINATION METER ASSY (SEE OVERHAUL
)
OK: END
5.INSPECT LIGHT CONTROL RHEOSTAT
a. Disconnect the light control rheostat connector.
b. Measure the voltage according to the value (s) in the table below.
Standard
LIGHT CONTROL RHEOSTAT VOLTAGE SPECIFICATIONS
NG: REPLACE LIGHT CONTROL RHEOSTAT
Terminal NoConditionSpecified condition
1 - 2Rheostat knob turned fully clockwiseApprox. 0 kohms
1 - 2Rheostat knob turned fully counterclockwiseApprox. 10 +/- 2 kohms
1 - 3AlwaysApprox. 10 +/- 2 kohms
4 - 1,3Rheostat knob turned fully counterclockwise10 kohms or higher
4 - 1,3Rheostat knob turned to fully clockwiseBelow 1 ohms

Fig. 85: Identifying D6 And R4 Connector Terminals
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
6.CHECK HARNESS AND CONNECTOR (LIGHT CONTROL RHEOSTAT - DRIVER SIDE
JUNCTION BLOCK) (SEE HOW TO PROCEED WITH TROUBLESHOOTING
)
a. Disconnect the D6 and R4 connectors.
b. Measure the resistance according to the value (s) in the table below.
Standard
D6 AND R4 CONNECTORS RESISTANCE SPECIFICATIONS
Tester ConnectionConditionSpecified Condition
D6-20 - R4-3AlwaysBelow 1 ohms
D6-22 - R4-2AlwaysBelow 1 ohms
D6-21 - R4-1AlwaysBelow 1 ohms
D6-1 - R4-4AlwaysBelow 1 ohms

Fig. 86: Identifying Terminal C12-19
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
OK: GO TO NEXT STEP

c. Check the deflection width of the speedometer indicator.
Reference: Below 0.5 km/h (0.3 mph)
2.INSPECT OUTPUT OF VEHICLE SPEED
a. Check the output signal waveform.
1. Remove the combination meter assy.
2. Connect the oscilloscope to terminal C12-19 and body ground.
3. Start the engine.
Fig. 87: Identifying Terminal C12
-19
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
4. Check the signal waveform according to the condition (s) in the table below.
SIGNAL WAVEFORM CONDITIONS
ItemCondition
Tool setting5 V/DIV, 20 ms/DIV

OK:
As shown in the illustration
HINT:
As vehicle speed increases, the cycle of the signal waveform narrows.
Fig. 88: Identifying Signal Waveform

Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
3.INSPECT TACHOMETER
a. Check operation
b. Connect the tune-up test tachometer and start the engine.
Vehicle conditionDriving at approx. 20 Km/h (12 mph)