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Multiplex Control Unit Input Test

  1. Remove the driver's dashboard lower cover (see DRIVER'S DASHBOARD LOWER COVER REMOVAL/INSTAL ).
  2. Disconnect the under-dash fuse/relay box connectors C, E, F, J, K, 0, P, Q, X and Y.
    NOTE: All connectors are wire side of female terminals.
    Fig 1: Identifying Multiplex Control Unit Connector Terminals
    G03676521Courtesy of AMERICAN HONDA MOTOR CO., INC.
  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.
  4. Reconnect the connectors to the under-dash fuse/relay box, 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.
    MULTIPLEX CONTROL UNIT INPUT TEST

    Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained
    J4 BLK Under all conditions Check for voltage to ground:
    There should be less than 1 V.
    • Poor ground (G301)
    • An open in the wire
    Y6 BLK Under all conditions Check for voltage to ground:
    There should be less than 1 V.
    • Poor ground (G502)
    • An open in the wire
    J2 WHT/RED Under all conditions Check for voltage to ground:
    There should be battery voltage.
    • Blown No. 9 (10A) fuse in the under-hood fuse/relay box
    • An open in the wire
    Q3 GRN 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
    Q4 LT GRN/RED Passenger's door open Check for voltage to ground:
    There should be less than 1 V.
    • Faulty passenger's door switch
    • An open in the wire
    Passenger's door closed Check for voltage to ground:
    There should be 5 V or more.
    • Faulty passenger's door switch
    • Short to ground
    Q2 GRN/WHT Hatch glass open Check for voltage to ground:
    There should be less than 1 V.
    • Poor ground (G601, G701)
    • Faulty hatch glass latch switch
    • An open in the wire
    Hatch glass closed Check for voltage to ground:
    There should be 5 V or more.
    • Faulty hatch glass latch switch
    • Short to ground
    Q8
    *
    C8
    *
    F1    		 GRN/ORN
    *
    GRN/ORN
    *
    GRN    		 Parking brake lever pulled Check for voltage to ground:
    There should be less than 1 V.
    • Faulty parking brake switch
    • An open in the wire
    Parking brake lever released Check for voltage to ground:
    There should be 5 V or more.
    • Faulty parking brake switch
    • Short to ground
    Q5 BLU/RED Ignition switch ON (II), driver's seat belt is unbuckled. Check for voltage to ground:
    There should be less than 1 V.
    • Faulty driver's seat belt buckle switch
    • Poor ground (G551)
    • An open in the wire
    Ignition switch ON (II), driver's seat belt is buckled. Check for voltage to ground:
    There should be 5 V or more.
    • Faulty driver's seat belt buckle switch
    • Short to ground
    P18 RED Tailgate open Check for voltage to ground:
    There should be less than 1 V.
    • Faulty tailgate switch
    • An open in the wire
    Tailgate closed Check for voltage to ground:
    There should be 5 V or more.
    • Faulty tailgate switch
    • Short to ground
    X5 RED/WHT Ignition key is in the ignition switch Check for voltage to ground:
    There should be less than 1 V.
    • Faulty ignition key 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 key switch
    • Short to ground
    X8 WHT/BLK Under all conditions Attach to ground:
    The ignition key light should come on.
    • Blown No. 3 (15A) fuse in the under-hood fuse/relay box
    • Blown LED
    • An open in the wire
    07 GRN/RED Ceiling light switch in the middle position, all doors closed Attach to ground:
    The ceiling light should come on.
    • Blown No. 3 (15A) fuse in the under-hood fuse/relay box
    • Faulty ceiling light
    • An open in the wire
    C11 BLU Under all conditions Attach to ground:
    Dash lights should come on.
    • Blown No. 6 (15A) fuse in the under-hood fuse/relay box
    • Faulty taillight relay
    • An open in the wire
    F8 GRN Disconnect the brake fluid level switch 2P connector, and jump the GRN and BLK wires Check for voltage to ground:
    There should be less than 1 V.
    • Faulty brake fluid level switch
    • An open in the wire
    Brake fluid level switch connector disconnected, jumper wire removed Check for voltage to ground:
    There should be 5 V or more.
    • Faulty brake fluid level switch
    • Short to ground
    E10 YEL All doors, tailgate and hatch glass closed, ignition key removed Check for voltage to ground:
    There should be battery voltage in the sleep mode and 3-7 V when awake.    		 An open or short in the wire
    K10 GRY/RED All doors, tailgate and hatch glass closed, ignition key removed Check for voltage to ground:
    There should be battery voltage in the sleep mode and 3-7 V when awake.    		 An open or short in the wire
    K2 BLU/ORN
    Y1 BRN/YEL Under all conditions Check for continuity between the Y1 terminal and the No. 13 terminal of the VSA modulator-control unit:
    There should be continuity    		 An open in the wire
    F9 BLU/WHT Under all conditions Check for voltage to ground:
    There should be 5 V or more.    		 An open or short in the wire
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