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Home › Lexus › 1990 › LS 400 › Repair and Diagnosis › Brakes › Traction Control › Traction Control System › Diagnostic Charts › Code 11 & 12: TRAC Brake Main Relay Circuit › Diagnostic Chart

Diagnostic Chart

  1. Turn ignition ON. Check for battery voltage between terminal 1 of TRAC brake main relay and body ground. If there is no voltage, check harness and connector between TRAC brake main relay and battery. If voltage is present, go to next step. Turn ignition OFF.
  2. Check TRAC brake main relay. Check continuity between each terminal of TRAC brake main relay. Terminals 1 and 2 should be open, continuity should exist between terminals 3 and 4. Apply battery voltage between terminals 3 and 4. Check continuity between terminals 1 and 2. If continuity exists TRAC brake main relay is okay. If relay is not functioning properly, replace. If relay is okay, go to next step.
  3. Check harness and connector between A.B.S. & TRAC ECU and TRAC brake main relay, TRAC brake main relay and TRAC actuator. Repair or replace any harness or connector found to be faulty. If harness is okay, check and replace A.B.S. & TRAC ECU.
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