Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2003 Lexus LS 430FACTORY OEM SERVICE PROCEDURE
Lighting System: Inspection
WARNING: This page is about a different car, the 2004 Toyota 4Runner. However, it is still accessible from the selected car via links, so may be relevant.
- HEADLAMP DIMMER SWITCH ASSY
- Inspect the light control switch continuity.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- Check that there is continuity between terminals at each switch position as shown in the chart.
SPECIFIED CONDITIONSwitch operation Tester connection Specified condition OFF - No continuity TAIL 14-16 Continuity HEAD 13-16 - 14 Continuity AUTO 16-12 Continuity - Inspect the headlamp dimmer switch continuity.
- Check that there is continuity between terminals at each switch position as shown in the chart.
SPECIFIED CONDITIONSwitch operation Tester connection Specified condition FLASH 7-8 - 16 Continuity LOW BEAM 16-17 Continuity HI BEAM 7-16 Continuity - Inspect the turn signal switch continuity.
- Check that there is continuity between terminals at each switch position as shown in the chart.
SPECIFIED CONDITIONSwitch operation Tester connection Specified condition Right turn 2-3 Continuity Neutral - No continuity Left turn 1-2 Continuity - Inspect the front fog lamp switch continuity.
- Check that there is continuity between terminals at each switch position as shown in the chart.
SPECIFIED CONDITIONSwitch operation Tester connection Specified condition OFF - No continuity ON 10-11 Continuity
- Inspect the light control switch continuity.
- HAZARD WARNING SIGNAL SWITCH ASSY
- Check that there is continuity between terminals at each switch position as shown in the chart.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
SPECIFIED CONDITIONSwitch operation Tester connection Specified condition OFF 2-3 No continuity ON 2-3 Continuity Illumination circuit 4-5 Continuity - Inspect illumination operation.
- Connect the battery positive (+) lead to terminal 4 and the battery negative (-) lead to terminal 5, then check that the illumination lights up.
- FOG LAMP RELAY
- Inspect the relay continuity.
SPECIFIED CONDITIONCondition Tester connection Specified condition Constant 1-2 Continuity Constant 3-5 No continuity Apply B+ between terminals 1 and 2. 3-5 Continuity - ROOF CONSOLE BOX ASSY
- Inspect the map lamp continuity.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- Check that there is continuity between terminal 1 and 5 when the switch is operated.
Standard:
ON: Continuity
OFF: No continuity
- Inspect the map lamp continuity.
- ROOM LAMP ASSY NO.1
- Inspect the room lamp assy No.1 continuity.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- Check that there is continuity between terminals at each switch position as shown in the chart.
STANDARDSwitch operation Tester connection Specified condition OFF - No continuity DOOR 1-2 Continuity ON 1-3 Continuity
- Inspect the room lamp assy No.1 continuity.
- ROOM LAMP ASSY NO.2
- Inspect the room lamp assy No.2 continuity.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- Check that there is continuity between terminals at each switch position as shown in the chart.
STANDARDSwitch operation Tester connection Specified condition OFF - No continuity DOOR 1-2 Continuity ON 1-3 Continuity
- Inspect the room lamp assy No.2 continuity.
- COURTESY LAMP ASSY
- Inspect the courtesy lamp assy continuity.
- Check that there is continuity between terminals when the switch is operated.
Standard:
ON (When shaft is pressed): No continuity
OFF (When shaft is not pressed): Continuity
- Inspect the courtesy lamp assy continuity.
- GLOVE BOX LAMP ASSY
- Inspect the glove box lamp assy continuity.
- Check that there is continuity between terminals when the switch is operated.
Standard:
ON (When shaft is pressed): No continuity
OFF (When shaft is not pressed): Continuity
- Inspect the glove box lamp assy continuity.
- LH STEP SUB-ASSY
- Inspect the side step lamp assy.
- Check that there is continuity between terminals when the courtesy lamp switch is operated.
Standard:
ON: Continuity
OFF: No continuity
- Inspect the rear wheel lamp assy.
- Check that there is continuity between terminals when the courtesy lamp switch is operated. Standard: ON: Continuity OFF: No continuity
Standard:
ON: Continuity
OFF: No continuity
- Inspect the side step lamp assy.
- TAIL LAMP RELAY
- Inspect relay continuity.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
STANDARDCondition Tester connection Specified condition Constant 1-2 Continuity Constant 3-5 No continuity Apply B+ between terminal 1 and 2 3-5 Continuity - HEADLAMP RELAY
- Inspect relay continuity.
STANDARDCondition Tester connection Specified condition Constant 1-2 Continuity Constant 3-5 No continuity Apply B+ between terminal 1 and 2 3-5 Continuity - STOP LAMP SWITCH ASSY
- Check that the continuity between terminals at each switch position, as shown in the chart.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
STANDARDSwitch position Tester connection Specified condition Switch pin free 1-2 No continuity Switch pin free 3-4 Continuity Switch pin pushed in 1-2 Continuity Switch pin pushed in 3-4 No continuity
- Check that there is continuity between terminals at each switch position as shown in the chart.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.