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Control Unit Input Test

WARNING: This page is about a different car, the 2008 Honda Pilot, 2007 Honda Pilot, and 2006 Honda Pilot. However, it is still accessible from the selected car via links, so may be relevant.
  1. Before testing, troubleshoot the multiplex control system (see TROUBLESHOOTING ).
  2. Remove the driver's multiplex control unit from the driver's under-dash fuse/relay box.
  3. 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 1: Identifying Multiplex Control System Connector Terminals
      G04247144Courtesy of AMERICAN HONDA MOTOR CO., INC.
  4. Reconnect the driver's multiplex control unit to the driver's under-dash fuse/relay box, and perform the following input tests at the appropriate connectors on the back of the driver's under-dash fuse/relay box. For driver's under-dash fuse/relay box connector socket location (see DRIVER'S 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, go to step 5.
      REFERENCE CHART (DRIVER'S MULTIPLEX CONTROL UNIT CONNECTED TO THE DRIVER'S UNDER-DASH FUSE/RELAY BOX)

      Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
      B11(1) BLK Under all conditions Check for voltage to ground:
      There should be less than 1 V.
      • Poor ground (G501)
      • An open in the wire
      E3 GRN/ORN Driver's door open Check for voltage to ground:
      There should be less than 1 V.
      • Faulty driver's door switch
      • An open in the wire
      Driver's door closed Check for voltage to ground:
      There should be 5 V or more.
      • Faulty driver's door switch
      • Short to ground
      M9 BLU/BLK Ignition key is in the ignition switch Check for voltage to ground:
      There should be less than 1 V.
      • Faulty ignition switch
      • Poor ground (G401)
      • An open in the wire
      Ignition key is out of the ignition switch Check for voltage to ground:
      There should be 5 V or more.
      • Faulty ignition switch
      • Short to ground
      M3 RED/BLK Combination light switch ON Check for voltage to ground:
      There should be battery voltage.
      • Blown No. 10 (15 A) fuse in the passenger's under-dash fuse/relay box
      • Faulty taillight relay
      • Faulty combination light switch
      • Faulty driver's under-dash fuse/ relay box
      • An open in the wire
      (1) Multiplex control unit connector B
  5. Remove the driver's multiplex control unit from the driver's multiplex control unit and make these input tests at the connector and driver's under-dash fuse/relay box sockets.
    • If any test indicates a problem, find and correct the cause, then recheck the system.
    • If all the input tests prove OK, go to GAUGE CONTROL MODULE INPUT TEST  (see ).
      REFERENCE CHART (DRIVER'S MULTIPLEX CONTROL UNIT DISCONNECTED TO THE DRIVER'S UNDER-DASH FUSE/RELAY BOX)

      Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
      A24 Fuse/relay box socket Ignition switch ON (II) Check for voltage to ground:
      There should be battery voltage.
      • Blown No. 9 (10 A) fuse in the driver's under-dash fuse/relay box
      • Faulty driver's fuse/relay box
      A12 Under all conditions Check for voltage to ground:
      There should be battery voltage.
      • Blown No. 13 (7.5 A) fuse in the passenger's under-dash fuse/relay box
      • An open in the wire
      A1 Under all conditions Attach to ground:
      The ignition key light should come on.
      • Blown No. 47 (20 A) fuse in the under-hood fuse/relay box
      • Faulty ignition key light
      • An open in the wire