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Power Circuits

  1. Using a voltmeter, check for battery voltage between ECU terminal D1 and ground. See Fig 1 . If battery voltage is not present, check EFI/ECU fuse in underhood fuse box. If fuse is okay, check for an open or short in Yellow/Blue wire between fuse box and control unit terminal D1.
  2. Turn ignition switch to ON position. DO NOT  start engine. Using a voltmeter, check for battery voltage between ECU terminal A25 and ground. See Fig 1 . If battery voltage is not present, check fuse No. 12 in dash fuse box. If fuse is okay, check for a defective ignition switch or an open or short in Black/Yellow wire between fuse box and ECU terminal A25.
    Fig 1: Identifying ECU Connector Pins
    G90E17123Courtesy of AMERICAN HONDA MOTOR CO., INC.