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Multiplex Control Unit Input Tests

NOTE: Before testing control unit inputs, ensure multiplex communications and control units are functioning properly. See MULTIPLEX CONTROL SYSTEMS - 3.5RL article.
  1. Remove driver's multiplex control unit from driver's underdash fuse/relay box. Disconnect control unit connectors. Inspect connectors and terminals. Check for bent, loose, or corroded terminals. Perform driver's multiplex control unit input tests. See Fig 1 . Repair as necessary and recheck system operation. If driver's multiplex control unit inputs are okay, go to next step.
  2. Reconnect driver's multiplex control unit to underdash fuse/relay box. Perform input tests as specified at back side of fuse/relay box (backprobe). See Fig 2 . Repair as necessary. If all tests are okay, go to next step.
  3. Remove passenger's multiplex control unit from passenger's underdash fuse/relay box. Disconnect 22-pin and 26-pin connectors. Inspect connectors and terminals. Check for bent, loose or corroded terminals. Perform passenger's multiplex control unit input tests. See Fig 3 . Repair as necessary and recheck system operation. If passenger's multiplex control unit inputs are okay, go to next step.
  4. Reconnect passenger's multiplex control unit to underdash fuse/relay box. Perform input tests as specified on passenger's fuse/relay box connectors. See Fig 4 . Repair as necessary. If all tests are okay, go to next step.
  5. Remove driver's door multiplex control unit (built into power window switch). Disconnect 20-pin connector. Inspect connectors and terminals. Check for bent, loose or corroded terminals. Perform driver's door multiplex control unit input tests. See Fig 5 . Repair as necessary and recheck system operation. If driver's door multiplex control unit tests are okay, go to next step.
  6. Reconnect driver's door multiplex control unit connector. Perform tests as specified by backprobing connector. See Fig 5 . Repair as necessary. If all tests are okay, go to next step.
  7. If all tests have proven okay, power window master switch must be faulty. Replace power window master switch and recheck system operation.
Fig 1: Driver's Multiplex Control Unit Input Test (1 Of 2)
G99H50028Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig 2: Driver's Multiplex Control Unit Input Test (2 Of 2)
G99I50029Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig 3: Passenger's Multiplex Control Unit Input Test (1 Of 2)
G99B50030Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig 4: Passenger's Multiplex Control Unit Input Test (2 Of 2)
G99D50032Courtesy of AMERICAN HONDA MOTOR CO., INC.
Fig 5: Driver's Door Multiplex Control Unit Input Tests
G99C50031Courtesy of AMERICAN HONDA MOTOR CO., INC.
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