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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 83 (Air Bag Restraint Systems) >> Diagnostic Tests >> DTC 25/B1153: Seat Position Sensor Malfunction >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition switch to LOCK position. Wait at least 20 seconds. Turn ignition switch to ON position. Wait at least 20 seconds. Retrieve DTCs. See RETRIEVING DTCS  under DIAGNOSTICS. If DTC 25/1153 is displayed, go to next step. If DTC 25/1153 is not displayed, system is functioning properly at this time. Check for intermittent fault. See AIR BAG WARNING LIGHT INTERMITTENT .
  2. Disable air bag system. See DISABLING SYSTEM  under DISABLING & ACTIVATING AIR BAG SYSTEM. Access air bag sensor assembly and inspect for proper connection of harness connectors. See AIR BAG SENSOR ASSEMBLY  under REMOVAL & INSTALLATION. If air bag sensor assembly connectors are not properly connected, reconnect connectors and perform system operation check. See SYSTEM OPERATION CHECK . If air bag sensor assembly connectors are properly connected, go to next step.
  3. Access seat position sensor and inspect for proper connection of harness connector. See SEAT POSITION SENSOR  under REMOVAL & INSTALLATION. If seat position sensor connectors are not properly connected, reconnect connectors and perform system operation check. If seat position sensor connectors are properly connected, go to next step.
  4. Disconnect air bag sensor assembly harness connector A30. Disconnect seat position sensor harness connector. Connect jumper wire between Blue/Black wire and Gray/Black wire (circuit D2-) on harness side seat position sensor connector. Measure resistance between harness side air bag sensor assembly connector A30, terminals No. 1 and 2. See Figure. If resistance is more then one ohm, go to step  9. If resistance is less than one ohm, go to next step.
  5. Remove jumper wire from seat position sensor harness connector. Measure resistance between ground harness side air bag sensor assembly connector A30, terminals No. 1 and 2. If resistance is less then one megohm, go to step  10. If resistance is more than one megohm, go to next step.
  6. Measure resistance between harness side air bag sensor assembly connector A30, terminals No. 1 and 2. If resistance is less then one megohm, go to step  11. If resistance is more than one megohm, go to next step.
  7. Connect negative battery cable. Turn ignition switch to ON position. Measure voltage between ground and harness side air bag sensor assembly connector A30, terminals No. 1 and 2. See Figure. If voltage is more then one volt, go to step  12. If voltage is less than one volt, go to next step.
  8. Turn ignition switch to LOCK position. Disconnect negative battery cable. Wait at least 90 seconds. Reconnect seat position sensor harness connector. Reconnect air bag sensor assembly harness connector A30. Connect negative battery cable. Wait at least 2 seconds. Turn ignition switch to ON position. Wait at least 20 seconds. Clear DTCs. See CLEARING DTCS  under DIAGNOSTICS. Turn ignition switch to LOCK position. Wait at least 20 seconds. Turn ignition switch to ON position. Wait at least 20 seconds. Retrieve DTCs. If DTC 25/1153 is displayed, replace seat position sensor. If DTC 25/1153 is not displayed, air bag system is functioning normally at this time. Check for intermittent fault. See AIR BAG WARNING LIGHT INTERMITTENT .
  9. Disconnect floor harness connector between seat position sensor and air bag sensor assembly. Measure resistance between Blue/Black and Gray/Black wires on seat position sensor side of floor harness connector. See WIRING DIAGRAMS . If resistance is more than one ohm, replace wiring harness between seat position sensor and floor harness connector. If resistance is less than one ohm, replace wiring harness between air bag sensor assembly and floor harness connector.
  10. Disconnect floor harness connector between seat position sensor and air bag sensor assembly. Measure resistance in Blue/Black wire between ground and seat position sensor side of floor harness connector. See WIRING DIAGRAMS . Measure resistance in Gray/Black wire between ground and seat position sensor side of floor harness connector. If resistance is more than one megohm in either circuit, replace wiring harness between air bag sensor assembly and floor harness connector. If resistance is less than one megohm in both circuits, replace wiring harness between seat position sensor and floor harness connector.
  11. Turn ignition switch to LOCK position. Disconnect negative battery cable. Wait at least 90 seconds. Disconnect floor harness connector between seat position sensor and air bag sensor assembly. Connect negative battery cable. Turn ignition switch to ON position. Measure voltage in Blue/Black wire between ground and seat position sensor side of floor harness connector. See WIRING DIAGRAMS . Measure voltage in Gray/Black wire between ground and seat position sensor side of floor harness connector. If voltage is more than one volt in either circuit, replace wiring harness between seat position sensor and floor harness connector. If voltage is less than one volt, replace wiring harness between air bag sensor assembly and floor harness connector.
  12. Turn ignition switch to LOCK position. Disconnect negative battery cable. Wait at least 90 seconds. Reconnect seat position sensor harness connector. Reconnect air bag sensor assembly harness connector A30. Connect negative battery cable. Wait at least 2 seconds. Turn ignition switch to ON position. Wait at least 20 seconds. Clear DTCs. See CLEARING DTCS  under DIAGNOSTICS. Turn ignition switch to LOCK position. Wait at least 20 seconds. Turn ignition switch to ON position. Wait at least 20 seconds. Retrieve DTCs. If DTC 25/1153 is displayed, replace seat position sensor. If DTC 25/1153 is not displayed, air bag system is functioning normally at this time. Check for intermittent fault. See AIR BAG WARNING LIGHT INTERMITTENT .
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