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Multiplex Control Unit Input Test

NOTE: Before continuing with the multiplex control unit input test, do the multiplex troubleshooting (see TROUBLESHOOTING  ).
  1. Remove the driver's dashboard lower cover (see DRIVER'S DASHBOARD LOWER COVER REMOVAL/INSTALLATION ).
  2. Disconnect the under-dash fuse/relay box connectors C, D, F, J, K, O, P, Q, R, X and Y.
    NOTE: All connectors are shown from wire side of female terminals.
    Fig 1: Identifying Under-Dash Fuse/Relay Box Connectors
    G05451553Courtesy 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 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.
      PROBLEM SYMPTOMS TABLE

      Cavity Wire Test condition Test: Desired result Possible cause if desired result is not obtained
      J4 BLK Under all conditions Measure voltage to ground: There should be less than 0.5 V.
      • Poor ground (G401)
      • An open in the wire
      Y6 BLK Under all conditions Measure voltage to ground: There should be less than 0.5 V.
      • Poor ground (G502)
      • An open in the wire
      J2 WHT/RED Under all conditions Measure voltage to ground: There should be battery voltage.
      • Blown No. 9 (10 A) fuse in the under-hood fuse/relay box
      • An open in the wire
      Q3 GRN Driver's or left rear door open Measure voltage to ground: There should be less than 0.5 V.
      • Faulty driver's or left rear door switch
      • An open in the wire
      Driver's and left rear door closed Measure voltage to ground: There should be battery voltage.
      • Faulty driver's or left rear door switch
      • Short to ground in the wire
      Q4 GRY/BLK Front passenger's or right rear door open Measure voltage to ground: There should be less than 0.5 V.
      • Faulty front passenger's or right rear door switch
      • An open in the wire
      Front passenger's and right rear door closed Measure voltage to ground: There should be battery voltage.
      • Faulty front passenger's or right rear door switch
      • Short to ground in the wire
      Q8 GRN/ORN Parking brake lever pulled Measure voltage to ground: There should be less than 0.5 V.
      • Faulty parking brake switch
      • An open in the wire
      Parking brake lever released Measure voltage to ground: There should be battery voltage.
      • Faulty parking brake switch
      • Short to ground in the wire
      • An open in the wire
      Q5 BLU/RED Ignition switch ON (II), driver's seat belt is unbuckled. Measure voltage to ground: There should be less than 0.5 V.
      • Faulty driver's seat belt buckle switch
      • Poor ground (G552)
      • An open in the wire
      Ignition switch ON (II), driver's seat belt is buckled. Measure voltage to ground: There should be battery voltage.
      • Faulty driver's seat belt buckle switch
      • Short to ground in the wire
      P18 RED Hatch or tailgate open Measure voltage to ground: There should be less than 0.5 V.
      • Faulty hatch latch or tailgate latch switch
      • An open in the wire
      Hatch and tailgate closed Measure voltage to ground: There should be battery voltage.
      • Faulty hatch latch or tailgate latch switch
      • Short to ground in the wire
      R4 (A/T) YEL/BLU Shift lever in P position Measure voltage to ground: There should be less than 0.5 V.
      • Faulty park pin switch
      • Poor ground (G401)
      • An open in the wire
      Shift lever in other than P position Measure voltage to ground: There should be battery voltage.
      • Faulty park pin switch
      • Short to ground in the wire
      X5 RED/WHT Ignition key is in the ignition switch. Measure voltage to ground: There should be less than 0.5 V.
      • Faulty ignition key switch
      • Poor ground (G401)
      • An open in the wire
      Ignition key is out of the ignition switch. Measure voltage to ground: There should be battery voltage.
      • Faulty ignition key switch
      • Short to ground in the wire
      X8 WHT/BLK With all doors closed Attach to ground: The ignition key light should come on.
      • Blown No. 3 (7.5 A) fuse in the under-hood fuse/relay box
      • Faulty ignition key light (LED)
      • An open in the wire
      O7 GRN/RED Front ceiling light switch in the middle [door] position, all doors closed Attach to ground: The front ceiling light should come on.
      • Blown No. 3 (7.5 A) fuse in the under-hood fuse/relay box
      • Faulty front ceiling light
      • An open in the wire
      C11 BLU Under all conditions Attach to ground: Dash lights should come on.
      • Blown No. 2 (15 A) fuse in the under-hood fuse/relay box
      • Faulty taillight relay
      • An open in the wire
      K2 BLU/ORN Disconnect under-dash fuse/relay box connector K(17P) and keyless receiver unit 5P connector Check for continuity between the K2 terminal and the keyless receiver unit 5P connector No. 2 terminal: There should be continuity. An open in the wire
      Check for continuity between the K2 terminal and the keyless receiver unit 5P connector No. 2 terminal: There should be no continuity. Short to ground in the wire
      K10 WHT/GRN Disconnect under-dash fuse/relay box connector K (17P) and gauge control module 36P connector Check for continuity between the K10 terminal and the gauge control module 36P connector No. 27 terminal: There should be continuity. An open in the wire
      Check for continuity to ground: There should be no continuity. Short to ground in the wire
      D10 (A/T) BLK/BLU Shift lever in P position Measure voltage to ground: There should be less than 0.5 V.
      • Poor ground (G101)
      • Faulty transmission range switch
      • An open in the wire
      Shift lever in other than P position Measure voltage to ground: There should be battery voltage.
      • Short to ground in the wire
      • An open in the wire
      F9 BLU/WHT Ignition switch ON (II), A/C switch OFF. Measure voltage to ground: There should be battery voltage.
      • Faulty under-dash fuse/relay box
      • Short to ground in the wire
      Ignition switch ON (II), A/C switch ON. Measure voltage to ground: There should be less than 0.5 V.
      • Faulty heater control panel
      • Faulty A/C pressure switch
      • An open in the wire
      F1(1)
      F8(1)      		 GRN/ORN Disconnect under-dash fuse/relay box connector F(12P) Check for continuity between the F1 and F8 terminals: There should be continuity. An open in the wire
      Check for continuity to ground: There should be no continuity. Short to ground in the wire
      F8(2) GRN/RED Disconnect under-dash fuse/relay box connector F(12P) and daytime running lights control unit 14P connector Check for continuity between the F8 terminal and daytime running lights control unit 14P connector No. 13 terminal: There should be continuity. An open in the wire
      Check for continuity to ground: There should be no continuity. Short to ground in the wire
      F1(2) GRN/ORN Disconnect under-dash fuse/relay box connector F(12P) and daytime running lights control unit 14P connector Check for continuity between the F1 terminal and daytime running lights control unit 14P connector No. 6 terminal: There should be continuity. An open in the wire
      Check for continuity to ground: There should be no continuity. Short to ground in the wire
      (1) '07-08 USA models
      (2) '07-08 Canada models

      [ ]: '09 model with overhead console
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