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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 90 (Multiplex Control Systems) >> Diagnostic Tests >> DTC B1272/72: Power Seat Ecu Communication Stopped >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check power seat operation by testing front vertical and rear vertical position functions. If front and rear vertical position functions are not okay, diagnose power seat ECU. See TROUBLE SHOOTING in POWER SEATS - AVALON article under SEATS in ACCESSORIES & EQUIPMENT. If front and rear vertical position functions operate normally, go to next step.
  2. Turn ignition off. Disconnect power seat ECU 25-pin electrical harness connector P21 and body control ECU 25-pin electrical harness connector B4. See Figure. Using DVOM, check continuity of Green/White wire between power seat ECU 25-pin electrical harness connector P21 terminal No. 14 and body control ECU 25-pin electrical harness connector P21 terminal No. 9. If continuity exists, diagnose power seat ECU. See TROUBLE SHOOTING in POWER SEATS - AVALON article under SEATS in ACCESSORIES & EQUIPMENT. If continuity does not exist, repair open circuit in Green/White wire between power seat ECU and body control ECU. See MEMORY SYSTEMS in SYSTEM WIRING DIAGRAMS article.
  3. After repairs have been made, perform confirmation test. See CONFIRMATION TEST  under SELF-DIAGNOSTIC SYSTEM.
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