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Home >> Lexus >> 1990 >> LS 400 >> Repair and Diagnosis >> Brakes >> Traction Control >> Traction Control System >> Diagnostic Charts >> Code 54 & 55: TRAC Pump Motor Relay Circuit >> Diagnostic Chart
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Diagnostic Chart

  1. Check voltage between terminal 1 of TRAC pump motor relay harness side connector and body ground. Remove TRAC pump motor relay. Turn ignition switch on. Measure voltage between terminal 1 of TRAC pump motor relay harness side connector and body ground. Battery voltage should be present. If voltage is not present, check and repair harness or connector between battery and TRAC pump motor relay. If voltage is present, go to next step.
  2. Check TRAC pump motor relay. Continuity should exist between terminals 3 and 4. Continuity should not exist between terminals 1 and 2. Apply battery voltage between terminals 3 and 4. There should be continuity between terminals 1 and 2. If relay is not okay, replace. If relay is okay, go to next step.
  3. Check continuity between terminals 2 and 3 of TRAC pump & motor connector. If there is no continuity, replace TRAC pump & motor. If there is continuity, go to next step.
  4. Check harness and connector between ABS & TRAC ECU and TRAC pump motor relay, ABS & TRAC ECU and TRAC pump motor, TRAC pump motor relay and TRAC pump & motor. Repair or replace any faulty connectors or harnesses. If connectors are okay, check and replace ABS & TRAC ECU.
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