Control Unit Input Test

Before testing the dash lights brightness control functions, troubleshoot the multiplex control system (see page TROUBLESHOOTING ).
Driver's Multiplex Control Unit
Remove the driver's multiplex control unit from the driver's under-dash fuse/relay box.
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 OK, go to step 4.
Fig 1: Identifying Driver's Under-Dash Fuse/Relay Box Socket
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 2: Identifying Driver's Multiplex Control Unit Connector B
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 3: Identifying Driver's Under-Dash Fuse/Relay Box Connector I
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 4: Identifying Driver's Under-Dash Fuse/Relay Box Connector O
Courtesy of AMERICAN HONDA MOTOR CO., INC.
With the control unit still disconnected, make these input tests at the connector and fuse/relay box socket.
- If any test indicates a problem, find and correct the cause, then recheck the system.
- If all the input tests prove OK, go to step 5.
Fig 5: Control Unit Input Test Identification Chart
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Reconnect the driver's multiplex control unit to the fuse/relay box, and perform the following input tests at the appropriate connectors on the back of the 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, go to step 6.
Fig 6: Control Unit Input Test Identification Chart
Courtesy of AMERICAN HONDA MOTOR CO., INC.
If all the input tests prove OK, the driver's multiplex control unit must be faulty. Substitute a known-good control unit, then recheck the system. If the system works properly, the original control unit is faulty; replace it.