Troubleshooting Car Alarms

Discussion in 'DIY - Do It Yourself Forum' started by Wildman, Apr 28, 2006.

  1. Wildman

    Wildman Read the rules

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    Originally posted by Blacknight, copied from the old forums

    Thought this info would be useful...

    Scenario 1: Alarm sounded for 30 seconds
    with no one in the vehicle

    • Scenario 2: Alarm sounded for 2 minutes while
    someone was in the vehicle

    • Scenario 3: Alarm sounded for 2 minutes with
    no one in the vehicle
    If you can’t duplicate your customer’s complaint
    at the dealership, ask your customer to time how
    long the alarm sounds and to describe the
    conditions when it does. Having accurate info
    greatly increases your chances of successful
    troubleshooting.

    Scenario 1: Alarm Sounded for 30 Seconds
    With No One in the Vehicle
    If the security system alarm sounded for 30
    seconds and then shut itself off, the Panic button
    on the remote transmitter got pressed and set off
    the panic alarm. This can easily happen if you
    lean over with the remote transmitter stuffed into
    your front pocket or you’re carrying something
    that presses against it. This is a normal
    characteristic of the security system, and can’t be
    fixed by replacing components. If your customer’s
    vehicle is a ’98–01 Accord EX, refer to S/B 01-003,
    Panic Alarm Sounds By Itself Intermittently.

    Scenario 2: Alarm Sounded for 2 Minutes
    While Someone Was in the Vehicle
    The security system alarm can sound while
    someone is in the vehicle. For this to happen,
    however, these things must have occured in this
    order:
    1. Someone unlocked the driver’s door, opened
    it, and climbed into the vehicle.
    2. With the door open, the person locked the
    doors with the power door lock switch or the
    driver’s door lock knob, then closed the door.
    3. The person waited 15 seconds or more
    before inserting the key into the ignition
    switch and turning the switch to ON (II).
    The alarm sounds until you remove the key from
    the ignition switch and press the unlock button on
    the remote transmitter, or you insert the key into
    the door lock cylinder and turn it to the unlock
    position.

    While the alarm is sounding and the lights are
    flashing, you can actually start the engine and
    drive the vehicle. The immobilizer system in these
    vehicles keeps the engine from starting unless you
    use a programmed ignition key, so there’s no need
    for starter and ignition cutoff.
    Because the door was locked while it was open,
    the security system couldn’t tell if anyone was in
    the vehicle or just standing outside. A backup
    feature gives you 15 seconds to insert the key
    into the ignition switch to signal you’re inside the
    vehicle. If the security system control unit doesn’t
    detect an ignition key cylinder switch signal
    within 15 seconds, the system assumes that
    you’re outside the vehicle and arms the system.
    This is a normal characteristic of the security
    system.

    Scenario 3: Alarm Sounded for 2 Minutes
    With No One in the Vehicle
    If the security system sounded for 2 minutes and
    then shut itself off, a security system switch was
    violated after the security system was armed. Here
    are the components that could be involved:
    • Hood switch
    • Door switch (any door)
    • Door lock knob switch (unlock)
    • Door key cylinder switch (lock/unlock)
    • Trunk switch
    • Tailgate key cylinder switch (Odyssey & Pilot)
    • Radio security ground
    • Ignition switch [turned to ON (II)]
    All switch circuits should be open (10 volts on the
    circuit) while the security system is armed. The
    only exceptions are the radio security ground and
    the driver’s door lock knob LOCK inputs, which
    are closed (0 volt on the circuit). If any of these
    switches change from their normal position,
    (open or closed), the security system reports a
    violation and sounds the alarm.
    The security system alarm keeps sounding until
    • You disarm the system by pressing any button
    on the remote transmitter.
    • You disarm the system by unlocking the doors
    with a key.
    • The system automatically resets after sounding
    for 2 minutes.

    Troubleshooting for Scenario 3: Alarm
    Sounded for 2 Minutes With No One in the
    Vehicle

    To troubleshoot this complaint, go to the
    Multiplex Control System subsection in the Body
    Electrical section of the appropriate S/M, and do
    the multiplex system self-diagnosis functions
    Mode 1 and Mode 2. Then do these steps:
    1. Go into self-diagnosis Mode 2.

    2. Lower all the windows. Close the hood, trunk,
    tailgate, and doors. Lock the doors.

    3. Check for oversensitive hood switch, trunk
    switch, or key cylinder switches (door,
    tailgate):
    • Push and pull on the hood, trunk, tailgate,
    and doors while listening for a beep from
    the multiplex system.
    • If you hear the multiplex system beep,
    check the switch that caused the system to
    beep. Check the adjustment of the switch
    and the component that activates it. If the
    adjustments are OK, unplug the switch, and
    recheck. If the problem goes away, replace
    the switch.
    • If the problem remains or the multiplex
    system didn’t beep, go to step 4.

    4. Check for an oversensitive door lock knob
    switch:
    • Slowly pull up on each door lock knob, one
    at a time.
    • If you hear the multiplex system beep when
    you touch the lock knob, or a lock knob is
    more sensitive to movement than the other
    lock knobs, check its linkage. If the linkage
    is OK, unplug the switch that’s
    oversensitive, and recheck. If the problem
    goes away, replace the oversensitive switch.
    • If the problem remains, go to step 5.

    5. Check for an oversensitive door switch:
    • Tap on and around each door switch.
    • If you hear the multiplex system beep when
    you tap on a switch (but you don’t push it),
    the switch is too sensitive. Look for cut or
    pinched wires near the area where you’re
    tapping. If the wires are OK, unplug the
    switch. If the problem goes away, replace
    the switch.
    • If the problem remains, go to step 6.

    6. Check for a loose radio security ground wire:
    • Remove the radio trim bezel, and then tap,
    wiggle, push, and pull on the radio
    connector and its electrical harness.
    • If you hear the multiplex system beep, the
    radio security wire has a poor connection to
    ground. Tighten the loose connection. If the
    problem remains, check the vehicle for
    aftermarket accessories that sense sound or
    motion. If you find such an aftermarket
    accessory, disconnect it, and recheck.
     

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