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Home >> Lexus >> 1991 >> LS 400 >> Repair and Diagnosis >> Brakes >> Traction Control >> Traction Control System >> Diagnostic Charts >> Code 56: TRAC Pump Motor Lock Sensor Circuit >> Diagnostic Chart
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Diagnostic Chart

  1. Check operation of TRAC pump and motor. Disconnect TRAC pump & motor connector. Connect positive lead of battery to terminal 3 or TRAC pump and motor connector and negative battery lead to terminal 1.
    WARNING: Do not apply battery voltage for more than 3 sec.

    The TRAC pump motor should emit an operating sound. If pump and motor are okay, go to step 3). If pump and motor are not okay, go to next step.

  2. Check continuity between terminal 1 of TRAC pump & motor connector and body ground. Repair or replace any faulty connectors or harnesses. If connectors are okay, replace TRAC pump & motor.
  3. Check continuity between terminals 4 and 5 of TRAC pump & motor connector. Disconnect TRAC pump & motor connector. Check continuity between terminals 4 and 5 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. Repair or replace any faulty connectors or harnesses. If connectors are okay, check and replace ABS & TRAC ECU.
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