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Test No. 10: One Or All Manual Functions Do Not Operate

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. Turn ignition off. Remove power seat ECU with connectors still attached. See Figure. Using a DVOM, backprobe harness side of power seat ECU 25-pin electrical harness connector P21 with negative DVOM lead on terminal No. 19 (Brown wire) and positive DVOM lead on specified terminals of ECU 25-pin electrical harness connector P21. See Figure. See POWER SEAT CONTROL SWITCH CIRCUIT TESTING CONNECTIONS  table. Battery voltage should exist when ignition is off. No voltage should exist when ignition is on. If circuits test as specified, go to step  4. If circuits do not test as specified, go to next step.
  2. Check power seat control switch. See POWER SEAT CONTROL SWITCH  under COMPONENT TESTS. If power seat control switch is okay, go to next step. See MEMORY SYSTEMS in SYSTEM WIRING DIAGRAMS article. After repairs have been made, perform confirmation test. See CONFIRMATION TEST .
  3. Disconnect 25-pin electrical harness connector P21 from power seat ECU. Disconnect Gray 10-pin electrical harness connector P18 from power seat control switch. Using an ohmmeter, check for opens and shorts in wiring harnesses and electrical connectors between power seat ECU and power seat control switch. See MEMORY SYSTEMS in SYSTEM WIRING DIAGRAMS article. If wires, wiring harness and connectors are okay, go to next step. If wires, wiring harness and connectors are not okay, repair and/or replace as required. After repairs have been made, perform confirmation test. See CONFIRMATION TEST .
  4. Check power seat ECU ground circuits. If ground circuit resistance is greater than one ohm, repair or replace ground circuit. If ground circuit is okay, substitute original power seat ECU with a known-good unit and recheck manual switch operation of power seat system. If manual switch operation of power seat system operates properly, original power seat ECU was defective. If manual switch operation of power seat system still does not operate properly, perform power seat ECU pin voltage check. See PIN VOLTAGE TESTS . Check wiring harness and electrical connectors for an intermittent problem. Repair wiring harnesses or connectors as necessary. If voltage values, harnesses and connectors are okay, replace power seat ECU. After repairs have been made, perform confirmation test. See CONFIRMATION TEST .
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