1998 Lexus LS 400FACTORY OEM SERVICE PROCEDURE

Headlight Control Switch Circuit

NOTE: If LEXUS scan tool is available, start test from step 1). If this scan tool is not available, start test from step 2).

  1. Check Headlight Control Switch Using Scan Tool

    Using scan tool, check headlight control switch using DATA LIST. If headlight switch is not okay, go to next step. If headlight switch is okay, go to next test listed in appropriate TROUBLE SHOOTING SYMPTOMS table.

  2. Check Headlight Control Switch

    Check headlight control switch. See STEERING COLUMN SWITCHES article. If headlight control switch is okay, go to next step. Replace headlight control switch as necessary. Retest system operation.

  3. Check Circuits

    Check circuits for faults between headlight control switch and body control ECU. See WIRING DIAGRAMS. Repair or replace as necessary. If circuits are okay, go to next test listed in appropriate TROUBLE SHOOTING SYMPTOMS table.
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

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.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.