Multiplex Control Unit Input Test

WARNING: This page is about a different car, the 2005 Honda Civic, 2004 Honda Civic, 2003 Honda Civic, and 2002 Honda Civic. However, it is still accessible from the selected car via links, so may be relevant.

Remove the driver's dashboard lower cover (see DRIVER'S DASHBOARD LOWER COVER REMOVAL/INSTALLATION ).
Disconnect the under-dash fuse/relay box connectors C, E, F, J, K, O, P, Q, X and Y.
NOTE: All connectors are wire side of female terminals.

Fig 1: Identifying Multiplex Control Unit Connector Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Inspect the connector and socket terminals to be sure they are all making good contact.
- If the terminals are bent, loose or corroded, repair them as necessary, and recheck the system.
- If the terminals look OK, go to step 4.
Fig 2: Multiplex Control Unit Input Test (Connectors Disconnected)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Reconnect the connectors to the under-dash fuse/relay box, turn the ignition switch ON (II) to keep the system awake and make sure these input tests at the appropriate connectors on the under-dash fuse/relay box.
- If any test indicates a problem, find and correct the cause, then recheck the system.
- If all the input tests prove OK, the multiplex control unit must be faulty. Replace the under-dash fuse/relay box assembly.
Fig 3: Multiplex Control Unit Input Test (Connectors Connected - 1 Of 2)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 4: Multiplex Control Unit Input Test (Connectors Connected - 2 Of 2)

Courtesy of AMERICAN HONDA MOTOR CO., INC.