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Home >> Lexus >> 2000 >> LX 470 >> Repair and Diagnosis >> Brakes >> Traction Control >> Anti-Lock Brake System/Vehicle Skid Control >> Troubleshooting >> Brake Warning Light >> Diagnostic Procedure

Diagnostic Procedure

  1. Turn ignition on. Observe BRAKE warning light. If BRAKE warning light illuminates, go to step  6. If BRAKE warning light does not illuminate, replace light bulb as necessary. Recheck warning light operation. If bulb is okay or if BRAKE warning light still does not illuminate, go to next step.
  2. Check parking brake switch. To check parking brake switch, disconnect parking brake switch harness connector. Connect DVOM between switch body and switch terminal. Push switch pin in (OFF), continuity should not exist. Release switch pin (ON), continuity should exist. Replace parking brake switch if continuity is not as specified. If parking brake switch is okay, go to next step.
  3. Check fluid level warning switch. To check fluid level warning switch, disconnect fluid level warning switch harness connector. Connect DVOM between switch terminals. With fluid level in MIN level (float up), continuity should not exist. Remove fluid from master cylinder reservoir (float down), continuity should exist. If continuity is as specified, refill master cylinder and go to next step. If continuity is not as specified, replace fluid level warning switch. Refill master cylinder.
  4. Perform ABS self-diagnostics. See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTC(s) can be displayed, diagnose affected DTC(s). If DTC(s) cannot be displayed, go to next step.
  5. Check if other warning lights are illuminated. If other warning lights are illuminated, go to step  7. If other warning lights are not illuminated, go to next step.
  6. Turn ignition off. Remove IG1 No. 1 relay from underhood relay box. Check continuity between specified relay terminals. See Figure. See IG1 NO. 1 RELAY CONTINUITY  table. Replace relay. If relay is okay, go to next step.
  7. Inspect circuit between IG1 No. 1 relay and combination meter. See WIRING DIAGRAMS . Repair as necessary. If circuit okay, go to next step.
  8. Inspect BRAKE warning light circuit or for faulty combination meter. Repair circuit or replace combination meter. If circuit or combination meter is okay, replace ABS/BA/TRAC/VSC ECU.
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