Troubleshooting Car Alarms

Wildman

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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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