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Power Circuits

  1. Ensure ignition is off. Disconnect connectors from ECU. Remove connector locks so ECU connector can be easily backprobed. See Fig 1. Reconnect ECU connectors.
  2. Turn ignition on. Using a DVOM, measure voltage between ground and ECU terminals BATT, IG SW, M-REL, +B and +B1. See Fig 2. Battery voltage should be present.
  3. If battery voltage is not present, check MAIN fuse and EFI fuse. Also ensure wiring harness is not open or shorted. If fuses and wiring harness are okay and conditions indicate ECU may be faulty, substitute a known good ECU. If condition improves, replace original ECU.
Fig 1: Locating ECU Connector Locks
G90D18849Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: ECU Terminal ID
G92C26114Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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