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To Enter Mode 1

WARNING: This page is about a different car, the 2006 Acura MDX, 2005 Acura MDX, 2004 Acura MDX, and 2003 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check the No. 9 (10 A) fuse in the driver's under-dash fuse/relay box and the No. 13 (7.5 A) fuse in the passenger's under-dash fuse/relay box.

    Are the fuses OK? 

    1. YES  - Go to step 2.
    2. NO  - Find and repair the cause of the blown fuse.
  2. Connect the special tool (A) to the multiplex control inspection connector (B).
    Fig 1: Connecting Special Tool To Multiplex Control Inspection Connector
    G03642313Courtesy of AMERICAN HONDA MOTOR CO., INC.
  3. Turn the ignition switch ON (II). If the driver's seat belt is unbuckled, the seat belt reminder will beep five times. For '04-06 models: Buckle the driver's seat belt or insert the special tool to the multiplex control inspection connector after turning the ignition switch ON (II) for 5 seconds, so seat belt reminder does not overlap MPCS check mode function beeping.
  4. After about 5 seconds, the ignition key light should come on and the beeper should beep for 2 seconds, go off for 0.2 seconds, then blink and beep for 0.2 second. This means that you are in Mode 1 of the self-diagnosis function. Check self-diagnosis function Mode 1 for a diagnostic trouble code (DTC).

    MODE 1: IGNITION KEY LIGHT and BEEPER 

    Fig 2: Identifying Ignition Key Light And Beam Pattern
    G03642314Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Did the multiplex system enter Mode 1 ? 

    1. YES  - Go to step 5.
    2. NO  - Go to step  6 .
  5. Check for a DTC.
    • If there are no DTCs present:

      The ignition key light and beeper will not blink/ beep again after the Mode 1 indication.

    • If there is a DTC present:

      About 1 second after entering mode 1, the ignition key light and beeper indicate the DTC(s). then repeat it every 3 seconds. If there is more than one DTC, the system will indicate them in succeeding order.

      Is there a DTC present? 

    1. YES  - Follow the procedure in the chart below.
    2. NO  - Go to Mode 2.
    MULTIPLEX CONTROL SYSTEM TROUBLESHOOTING

    DTC(s) Cause Procedure
    1 The driver's unit is unable to receive signals from the door unit. Go to BRN wire communication line test.
    2 The driver's unit is unable to receive signals from the passenger's unit. Go to PNK wire communication line test.
    3 (Ignore this DTC is vehicle does not have DPMS.) The driver's unit is unable to receive signals from the power seat control unit. Go to PNK wire communication line test.
    5 Malfunction in the driver's unit Go to multiplex control system input test, if all inputs are OK, replace driver's multiplex control unit.
    6 The door unit is not able to receive signal from the other units. Go to multiplex control system input test if all inputs are OK, replace door multiplex control unit.
    7 The passenger's unit is not able to receive signal from the other units. Go to multiplex control system input test, if all inputs are OK replace passenger's multiplex control unit.
    8 Power seat control unit is unable to receive signals from the other units. Go to the DPMS input test, if all inputs are OK, replace the power seat control unit.
    1, 2, 3 and 5 Simultaneously Communication (BRN or PNK) wire is shorted, (12 V or Ground) Go to shorted communication line test.
  6. Remove the special tool from the MPCS inspection connector.
  7. Remove driver's multiplex control unit from the driver's under-dash fuse/relay box.
  8. Check for voltage between the A24 terminal of the driver's fuse/relay box socket and body ground.
    Fig 3: Checking Voltage Between A24 Terminal Of Driver's Fuse/Relay Box Socket And Body Ground
    G03642315Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 9.
    2. NO  - Replace the driver's under-dash fuse/relay box.
  9. Turn ignition switch ON (II).
  10. Check for voltage between A12 terminal of the driver's fuse/relay box socket and body ground.
    Fig 4: Checking Voltage Between A12 Terminal Of Driver's Fuse/Relay Box Socket And Body Ground
    G03642316Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 11.
    2. NO  - Repair an open in the wire between the No. 13 fuse in the passenger's under-dash fuse/relay box socket and A12 terminal.
  11. Check for continuity between A14 terminal of the driver's under-dash fuse/relay box socket and body ground.
    Fig 5: Checking Continuity Between A14 Terminal Of Driver's Under-Dash Fuse/Relay Box Socket And Body Ground
    G03642317Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 12.
    2. NO  - Repair an open in the wire between driver's multiplex control unit connector and body ground. If the wire is OK, check for poor ground at G401.
  12. Check for continuity between the B11 terminal of the driver's multiplex control unit connector and body ground.
    Fig 6: Checking Continuity Between B11 Terminal Of Driver's Multiplex Control Unit Connector And Body Ground
    G03642318Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 13.
    2. NO  - Repair an open in the wire between the driver's multiplex control unit connector and ground. If the wire is OK, check for poor ground at G501.
  13. Check for continuity between the No. 3 terminal of the MPCS inspection connector and the A15 terminal of the driver's under-dash fuse/relay box socket.
    Fig 7: Checking Continuity Between No. 3 Terminal Of MPCS Inspection Connector And A15 Terminal Of Driver's Under-Dash Fuse/Relay Box Socket
    G03642319Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 14.
    2. NO  - Repair an open in the wire between the inspection connector and the driver's under-dash fuse/relay box. If the wire is OK, replace the driver's under-dash fuse/relay box.
  14. Check for continuity between the No. 1 terminal of the multiplex inspection connector and body ground.
    Fig 8: Checking Continuity Between No. 1 Terminal Of Multiplex Inspection Connector And Body Ground
    G03642320Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - If there is still no Mode 1 indication, replace the driver's multiplex control unit and recheck the symptom.
    2. NO  - Repair an open in the wire between the inspection connector and body ground. If the wire is OK, check for a poor ground at G401.
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