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Home >> Acura >> 2001 >> 3.2TL >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Multiplex Control Systems >> System Testing >> Self-Diagnostic System

Self-Diagnostic System

  1. Ensure fuse No. 9 (7.5-amp) in driver's underdash fuse/relay box and fuse No. 13 (7.5-amp) in passenger's underdash fuse/relay box are okay. If fuse(s) are blown, find and repair cause of blown fuse. See WIRING DIAGRAMS  . If fuse(s) are okay, go to next step.
  2. Locate multiplex control unit diagnostic test connector in driver's underdash fuse/relay box behind left kick panel. See Fig 1 . Turn ignition on. Connect SCS Service Connector (07WAZ-001010A) to multiplex control unit diagnostic test connector and wait for at least 5 seconds.
    Fig 1: Entering Self-Diagnostic Mode
    G99H05143Courtesy of AMERICAN HONDA MOTOR CO., INC.
  3. Observe ignition switch light and buzzer. Ignition switch light and buzzer should come on for 2 seconds, then off for .2 seconds, then back on again for .2 seconds. This confirms that you are in MODE 1 of self-diagnostics function. After entering MODE 1, go to next step. If ignition switch light and buzzer do not operate as specified, go to step  5 .
  4. If a DTC is present, ignition switch light and buzzer will indicate DTC by the number of times they turn on and off. If a DTC is indicated, go to step  7 . If no DTCs are indicated, go to next step.
  5. Check continuity between diagnostic connector terminal J1 and driver's multiplex control unit terminal A15. See WIRING DIAGRAMS  . If continuity exists, go to next step. If continuity does not exist, repair open circuit or replace driver's underdash fuse/relay box as necessary. After repairs, recheck for DTCs.
  6. Check continuity between ground and diagnostic connector terminal J3 (Black wire). If continuity is indicated, go to step  13 . If continuity is not indicated, repair open in circuit. After repairs, recheck for DTCs.
  7. One second after entering MODE 1, ignition switch light flashes and buzzer beeps to indicate DTC is present. If more than one DTC is present, system will indicate them in ascending order and will repeat every 3 seconds. See DTC DIAGNOSIS  . Note DTC(s) and go to next step.
    DTC DIAGNOSIS

    DTC Probable Cause
    1 (1) No Signal From Door Control Unit To Driver's Control Unit
    2 (1) No Signal From Passenger's Control Unit To Driver's Control Unit
    3 (2) Malfunction In Driver's Control Unit
    4 (1) Signal From Each Control Unit Does Not Match
    5 (1) No Signal From Other Control Units To Passenger's Control Unit
    6 (1) No Signal From Other Control Units To Door Control Unit
    (1) Diagnose using COMMUNICATION LINE TESTS  .
    (2) Replace driver's multiplex control unit and recheck DTCs.
  8. Test power and ground inputs to all 3 multiplex control units. See DOOR MULTIPLEX CONTROL UNIT  , DRIVER'S MULTIPLEX CONTROL UNIT  and PASSENGER'S MULTIPLEX CONTROL UNIT  . Repair as necessary. If no problem was found, go to next step.
  9. Check communication lines for continuity. Check for appropriate voltages at control units. See COMMUNICATION LINE TESTS  . Repair as necessary. If communication lines are okay, go to next step.
  10. Shift system to SLEEP mode. Turn ignition off. Open and close a door to cancel key off operation timer in power window system. Ensure that exterior lights are off. Multiplex control system will shift to SLEEP mode after one minute, if switches related to multiplex control unit are not operated. All switches, except door lock knob switches, must be in OFF position. Go to next step.
  11. Confirm SLEEP mode. Check for voltage on multiplex control unit wake-up communication lines (Brown wire for door-to-driver's control unit; Pink wire for driver's-to-passenger's control unit). See WIRING DIAGRAMS  . Battery voltage should be present. Check parasitic draw at battery while changing to sleep mode. Parasitic draw should change from 70-80 milliamps to less than 10-20 milliamps.
    NOTE: When ignition is turned on, all multiplex control units wake up at the same time, without talking to each other. When any switch in multiplex system is turned on, it wakes up its corresponding control unit, which in turn wakes the other control units. If any multiplex control unit is faulty and cannot wake up, several parts of multiplex system will not operate.
  12. Confirm WAKE UP mode. After confirming WAKE UP mode, check the following for switch most closely associated with the problem. Operate switch to see if its corresponding control unit wakes up.

    Passenger's multiplex control unit switches:

    • Front passenger's door switch
    • Front passenger's door key cylinder switch (LOCK/UNLOCK)
    • Front passenger's door lock switch (LOCK/UNLOCK)
    • Front passenger's door lock knob switch (UNLOCK)
    • Keyless entry transmitter (LOCK, UNLOCK & TRUNK buttons)
    • Radio switch (Switch is grounded through radio connector. Test switch by disconnecting connector from radio.)
    • Right rear door switch
    • Right rear door lock knob switch (UNLOCK)

    Driver's multiplex control unit switches:

    • Ignition key switch
    • Headlight switch
    • Driver's door switch
    • Left rear door switch
    • Left rear door lock knob switch (UNLOCK)
    • Trunk latch switch
    • Trunk key cylinder switch
    • Hood switch

    Door multiplex control unit switches:

    • Driver's door key cylinder switch (LOCK/UNLOCK).
    • Driver's door lock knob switch (LOCK/UNLOCK).
    • Driver's door lock switch (LOCK/UNLOCK).

    If all components operate properly, WAKE UP mode is okay. Go to next step. If WAKE UP mode does not function, trouble shoot and repair open or short in communication line(s). See WIRING DIAGRAMS  .

    NOTE: To enter self-diagnostic MODE 2, vehicle must already be in self-diagnostic MODE 1. To cancel MODE 2, remove SCS service connector for at least 10 seconds or turn ignition off.
  13. Activate MODE 2 diagnostics. To switch from MODE 1 to MODE 2, disconnect SCS Service Connector (07WAZ-0010100) for about 10 seconds, then reconnect SCS service connector. Ignition key light and beeper should come on for 2 seconds, then turn off and back on twice more at .2 second intervals. This confirms that system has gone from MODE 1 to MODE 2. Go to next step.
  14. Check the following lists and operate the switch most closely related to the problem.

    Passenger's multiplex control unit switches:

    • Front passenger's door switch.
    • Front passenger's key cylinder switch (LOCK/UNLOCK).
    • Front passenger's door lock switch (LOCK/UNLOCK).
      NOTE: When testing door lock knob, ensure that all other doors are locked.
    • Front passenger's door lock knob switch (UNLOCK).
    • Keyless entry transmitter (LOCK, UNLOCK & TRUNK buttons).
    • Radio switch (Switch is grounded through radio connector. Test switch by disconnecting connector from radio.)
    • Right rear door switch.
    • Right rear door lock knob switch (UNLOCK).

    Driver's multiplex control unit switches:

    • Generator "L" terminal.
    • A/T gear position switch (PARK).
    • Brake switch.
    • Dash lights brightness control.
    • Driver's door switch.
    • Driver's seat belt switch.
    • Hood switch.
    • Engine oil pressure switch.
    • Headlight switch.
    • Left rear door switch.
      NOTE: When testing door lock knob, ensure that all other doors are locked.
    • Left rear door lock knob switch (UNLOCK).
    • Parking brake switch.
    • Trunk latch switch.
    • Windshield wiper/washer switch, except MIST switch.

    Door multiplex control unit switches:

    • Driver's key cylinder switch (LOCK/UNLOCK).
    • Driver's door lock knob switch (LOCK/UNLOCK).
    • Driver's door lock switch (UNLOCK).
    • Power window master switch.

    If related circuit of switch operates properly, ignition key light will flash and buzzer will sound. Go to appropriate article in ACCESSORIES & EQUIPMENT to further diagnose problem. If circuit is faulty, there will be no system response when switch is operated. Go to next step.

  15. Check several other circuits listed for affected control unit. If ignition key light flashes and buzzer sounds when other switches are operated, repair short or open circuit to switch tested in previous step. Multiple failed circuits could mean that control unit has failed, even if DTC was not set. If several circuits have failed, substitute a known-good control unit, then recheck system. If there is still a malfunction, substitute a known-good control unit for next most likely failed control unit.
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