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Power Circuits

  1. Ensure ignition is off. Disconnect connectors from ECU. To measure ECU voltage, connect a Check Harness (SST 09990-01000) between ECU and wiring connectors. Do not backprobe connector.
  2. Turn ignition on. Using a DVOM, measure voltage between ground and ECU terminals E9-33, E10-69, E9-1, E9-31 and E9-32. See Fig 2. Battery voltage should be present.
  3. If battery voltage is not present, check 30-amp MAIN fuse. Also ensure wire harness is not open or shorted. If fuses and wire 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: Identifying ECU Terminals
G92D26115Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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